AsyncFreeSpec
Enables testing of asynchronous code without blocking,
using a style consistent with traditional AnyFreeSpec
tests.
Recommended Usage:
AsyncFreeSpec is intended to enable users of AnyFreeSpec
to write non-blocking asynchronous tests that are consistent with their traditional AnyFreeSpec tests.
Note: AsyncFreeSpec is intended for use in special situations where non-blocking asynchronous
testing is needed, with class AnyFreeSpec used for general needs.
|
Given a Future
returned by the code you are testing,
you need not block until the Future
completes before
performing assertions against its value. You can instead map those
assertions onto the Future
and return the resulting
Future[Assertion]
to ScalaTest. The test will complete
asynchronously, when the Future[Assertion]
completes.
Here's an example AsyncFreeSpec
:
package org.scalatest.examples.asyncfreespec import org.scalatest.freespec.AsyncFreeSpec import scala.concurrent.Future class AddSpec extends AsyncFreeSpec { def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "addSoon" - { "will eventually compute a sum of passed Ints" in { val futureSum: Future[Int] = addSoon(1, 2) // You can map assertions onto a Future, then return // the resulting Future[Assertion] to ScalaTest: futureSum map { sum => assert(sum == 3) } } } def addNow(addends: Int*): Int = addends.sum "addNow" - { "will immediately compute a sum of passed Ints" in { val sum: Int = addNow(1, 2) // You can also write synchronous tests. The body // must have result type Assertion: assert(sum == 3) } } }
In an AsyncFreeSpec
you write a test with a string followed by in
and the body of the
test in curly braces, like this:
"will eventually compute a sum of passed Ints" in { // ... }
You can nest a test inside any number of description clauses, which you write with a string followed by a dash character and a block, like this:
"addSoon" - { // ... }
You can nest description clauses as deeply as you want. Because the description clause is denoted with an operator, not
a word like should
, you are free to structure the text however you wish.
In short, you structure an AsyncFreeSpec
exactly like a AnyFreeSpec
, but with
tests having result type Assertion
or Future[Assertion]
. For more examples
of structure, see the documentation for AnyFreeSpec
.
Starting with version 3.0.0, ScalaTest assertions and matchers have result type Assertion
.
The result type of the first test in the example above, therefore, is Future[Assertion]
.
For clarity, here's the relevant code in a REPL session:
scala> import org.scalatest._ import org.scalatest._ scala> import Assertions._ import Assertions._ scala> import scala.concurrent.Future import scala.concurrent.Future scala> import scala.concurrent.ExecutionContext import scala.concurrent.ExecutionContext scala> implicit val executionContext = ExecutionContext.Implicits.global executionContext: scala.concurrent.ExecutionContextExecutor = scala.concurrent.impl.ExecutionContextImpl@26141c5b scala> def addSoon(addends: Int*): Future[Int] = Future { addends.sum } addSoon: (addends: Int*)scala.concurrent.Future[Int] scala> val futureSum: Future[Int] = addSoon(1, 2) futureSum: scala.concurrent.Future[Int] = scala.concurrent.impl.Promise$DefaultPromise@721f47b2 scala> futureSum map { sum => assert(sum == 3) } res0: scala.concurrent.Future[org.scalatest.Assertion] = scala.concurrent.impl.Promise$DefaultPromise@3955cfcb
The second test has result type Assertion
:
scala> def addNow(addends: Int*): Int = addends.sum addNow: (addends: Int*)Int scala> val sum: Int = addNow(1, 2) sum: Int = 3 scala> assert(sum == 3) res1: org.scalatest.Assertion = Succeeded
When AddSpec
is constructed, the second test will be implicitly converted to
Future[Assertion]
and registered. The implicit conversion is from Assertion
to Future[Assertion]
, so you must end synchronous tests in some ScalaTest assertion
or matcher expression. If a test would not otherwise end in type Assertion
, you can
place succeed
at the end of the test. succeed
, a field in trait Assertions
,
returns the Succeeded
singleton:
scala> succeed res2: org.scalatest.Assertion = Succeeded
Thus placing succeed
at the end of a test body will satisfy the type checker:
"will immediately compute a sum of passed Ints" - { val sum: Int = addNow(1, 2) assert(sum == 3) println("hi") // println has result type Unit succeed // succeed has result type Assertion }
An AsyncFreeSpec
's lifecycle has two phases: the registration phase and the
ready phase. It starts in registration phase and enters ready phase the first time
run
is called on it. It then remains in ready phase for the remainder of its lifetime.
Tests can only be registered with the it
method while the AsyncFreeSpec
is
in its registration phase. Any attempt to register a test after the AsyncFreeSpec
has
entered its ready phase, i.e., after run
has been invoked on the AsyncFreeSpec
,
will be met with a thrown TestRegistrationClosedException
. The recommended style
of using AsyncFreeSpec
is to register tests during object construction as is done in all
the examples shown here. If you keep to the recommended style, you should never see a
TestRegistrationClosedException
.
== Asynchronous execution model ==
AsyncFreeSpec
extends AsyncTestSuite
, which provides an
implicit scala.concurrent.ExecutionContext
named executionContext
. This
execution context is used by AsyncFreeSpec
to
transform the Future[Assertion]
s returned by each test
into the FutureOutcome
returned by the test
function
passed to withFixture
.
This ExecutionContext
is also intended to be used in the tests,
including when you map assertions onto futures.
On both the JVM and Scala.js, the default execution context provided by ScalaTest's asynchronous
testing styles confines execution to a single thread per test. On JavaScript, where single-threaded
execution is the only possibility, the default execution context is
scala.scalajs.concurrent.JSExecutionContext.Implicits.queue
. On the JVM,
the default execution context is a serial execution context provided by ScalaTest itself.
When ScalaTest's serial execution context is called upon to execute a task, that task is recorded
in a queue for later execution. For example, one task that will be placed in this queue is the
task that transforms the Future[Assertion]
returned by an asynchronous test body
to the FutureOutcome
returned from the test
function.
Other tasks that will be queued are any transformations of, or callbacks registered on, Future
s that occur
in your test body, including any assertions you map onto Future
s. Once the test body returns,
the thread that executed the test body will execute the tasks in that queue one after another, in the order they
were enqueued.
ScalaTest provides its serial execution context as the default on the JVM for three reasons. First, most often
running both tests and suites in parallel does not give a significant performance boost compared to
just running suites in parallel. Thus parallel execution of Future
transformations within
individual tests is not generally needed for performance reasons.
Second, if multiple threads are operating in the same suite
concurrently, you'll need to make sure access to any mutable fixture objects by multiple threads is synchronized.
Although access to mutable state along
the same linear chain of Future
transformations need not be synchronized,
this does not hold true for callbacks, and in general it is easy to make a mistake. Simply put: synchronizing access to
shared mutable state is difficult and error prone.
Because ScalaTest's default execution context on the JVM confines execution of Future
transformations
and call backs to a single thread, you need not (by default) worry about synchronizing access to mutable state
in your asynchronous-style tests.
Third, asynchronous-style tests need not be complete when the test body returns, because the test body returns
a Future[Assertion]
. This Future[Assertion]
will often represent a test that has not yet
completed. As a result, when using a more traditional execution context backed by a thread-pool, you could
potentially start many more tests executing concurrently than there are threads in the thread pool. The more
concurrently execute tests you have competing for threads from the same limited thread pool, the more likely it
will be that tests will intermitently fail due to timeouts.
Using ScalaTest's serial execution context on the JVM will ensure the same thread that produced the Future[Assertion]
returned from a test body is also used to execute any tasks given to the execution context while executing the test
body—and that thread will not be allowed to do anything else until the test completes.
If the serial execution context's task queue ever becomes empty while the Future[Assertion]
returned by
that test's body has not yet completed, the thread will block until another task for that test is enqueued. Although
it may seem counter-intuitive, this blocking behavior means the total number of tests allowed to run concurrently will be limited
to the total number of threads executing suites. This fact means you can tune the thread pool such that maximum performance
is reached while avoiding (or at least, reducing the likelihood of) tests that fail due to timeouts because of thread competition.
This thread confinement strategy does mean, however, that when you are using the default execution context on the JVM, you
must be sure to never block in the test body waiting for a task to be completed by the
execution context. If you block, your test will never complete. This kind of problem will be obvious, because the test will
consistently hang every time you run it. (If a test is hanging, and you're not sure which one it is,
enable slowpoke notifications.) If you really do
want to block in your tests, you may wish to just use a
traditional AnyFreeSpec
with
ScalaFutures
instead. Alternatively, you could override
the executionContext
and use a traditional ExecutionContext
backed by a thread pool. This
will enable you to block in an asynchronous-style test on the JVM, but you'll need to worry about synchronizing access to
shared mutable state.
To use a different execution context, just override executionContext
. For example, if you prefer to use
the runNow
execution context on Scala.js instead of the default queue
, you would write:
// on Scala.js implicit override def executionContext = org.scalatest.concurrent.TestExecutionContext.runNow
If you prefer on the JVM to use the global execution context, which is backed by a thread pool, instead of ScalaTest's default serial execution contex, which confines execution to a single thread, you would write:
// on the JVM (and also compiles on Scala.js, giving // you the queue execution context) implicit override def executionContext = scala.concurrent.ExecutionContext.Implicits.global
== Serial and parallel test execution ==
By default (unless you mix in ParallelTestExecution
), tests in an AsyncFreeSpec
will be executed one after
another, i.e., serially. This is true whether those tests return Assertion
or Future[Assertion]
,
no matter what threads are involved. This default behavior allows
you to re-use a shared fixture, such as an external database that needs to be cleaned
after each test, in multiple tests in async-style suites. This is implemented by registering each test, other than the first test, to run
as a continuation after the previous test completes.
If you want the tests of an AsyncFreeSpec
to be executed in parallel, you
must mix in ParallelTestExecution
and enable parallel execution of tests in your build.
You enable parallel execution in Runner
with the -P
command line flag.
In the ScalaTest Maven Plugin, set parallel
to true
.
In sbt
, parallel execution is the default, but to be explicit you can write:
parallelExecution in Test := true // the default in sbt
On the JVM, if both ParallelTestExecution
is mixed in and
parallel execution is enabled in the build, tests in an async-style suite will be started in parallel, using threads from
the Distributor
, and allowed to complete in parallel, using threads from the
executionContext
. If you are using ScalaTest's serial execution context, the JVM default, asynchronous tests will
run in parallel very much like traditional (such as AnyFreeSpec
) tests run in
parallel: 1) Because ParallelTestExecution
extends
OneInstancePerTest
, each test will run in its own instance of the test class, you need not worry about synchronizing
access to mutable instance state shared by different tests in the same suite.
2) Because the serial execution context will confine the execution of each test to the single thread that executes the test body,
you need not worry about synchronizing access to shared mutable state accessed by transformations and callbacks of Future
s
inside the test.
If ParallelTestExecution
is mixed in but
parallel execution of suites is not enabled, asynchronous tests on the JVM will be started sequentially, by the single thread
that invoked run
, but without waiting for one test to complete before the next test is started. As a result,
asynchronous tests will be allowed to complete in parallel, using threads
from the executionContext
. If you are using the serial execution context, however, you'll see
the same behavior you see when parallel execution is disabled and a traditional suite that mixes in ParallelTestExecution
is executed: the tests will run sequentially. If you use an execution context backed by a thread-pool, such as global
,
however, even though tests will be started sequentially by one thread, they will be allowed to run concurrently using threads from the
execution context's thread pool.
The latter behavior is essentially what you'll see on Scala.js when you execute a suite that mixes in ParallelTestExecution
.
Because only one thread exists when running under JavaScript, you can't "enable parallel execution of suites." However, it may
still be useful to run tests in parallel on Scala.js, because tests can invoke API calls that are truly asynchronous by calling into
external APIs that take advantage of non-JavaScript threads. Thus on Scala.js, ParallelTestExecution
allows asynchronous
tests to run in parallel, even though they must be started sequentially. This may give you better performance when you are using API
calls in your Scala.js tests that are truly asynchronous.
== Futures and expected exceptions ==
If you need to test for expected exceptions in the context of futures, you can use the
recoverToSucceededIf
and recoverToExceptionIf
methods of trait
RecoverMethods
. Because this trait is mixed into
supertrait AsyncTestSuite
, both of these methods are
available by default in an AsyncFreeSpec
.
If you just want to ensure that a future fails with a particular exception type, and do
not need to inspect the exception further, use recoverToSucceededIf
:
recoverToSucceededIf[IllegalStateException] { // Result type: Future[Assertion] emptyStackActor ? Peek }
The recoverToSucceededIf
method performs a job similar to
assertThrows
, except
in the context of a future. It transforms a Future
of any type into a
Future[Assertion]
that succeeds only if the original future fails with the specified
exception. Here's an example in the REPL:
scala> import org.scalatest.RecoverMethods._ import org.scalatest.RecoverMethods._ scala> import scala.concurrent.Future import scala.concurrent.Future scala> import scala.concurrent.ExecutionContext.Implicits.global import scala.concurrent.ExecutionContext.Implicits.global scala> recoverToSucceededIf[IllegalStateException] { | Future { throw new IllegalStateException } | } res0: scala.concurrent.Future[org.scalatest.Assertion] = ... scala> res0.value res1: Option[scala.util.Try[org.scalatest.Assertion]] = Some(Success(Succeeded))
Otherwise it fails with an error message similar to those given by assertThrows
:
scala> recoverToSucceededIf[IllegalStateException] { | Future { throw new RuntimeException } | } res2: scala.concurrent.Future[org.scalatest.Assertion] = ... scala> res2.value res3: Option[scala.util.Try[org.scalatest.Assertion]] = Some(Failure(org.scalatest.exceptions.TestFailedException: Expected exception java.lang.IllegalStateException to be thrown, but java.lang.RuntimeException was thrown)) scala> recoverToSucceededIf[IllegalStateException] { | Future { 42 } | } res4: scala.concurrent.Future[org.scalatest.Assertion] = ... scala> res4.value res5: Option[scala.util.Try[org.scalatest.Assertion]] = Some(Failure(org.scalatest.exceptions.TestFailedException: Expected exception java.lang.IllegalStateException to be thrown, but no exception was thrown))
The recoverToExceptionIf
method differs from the recoverToSucceededIf
in
its behavior when the assertion succeeds: recoverToSucceededIf
yields a Future[Assertion]
,
whereas recoverToExceptionIf
yields a Future[T]
, where T
is the
expected exception type.
recoverToExceptionIf[IllegalStateException] { // Result type: Future[IllegalStateException] emptyStackActor ? Peek }
In other words, recoverToExpectionIf
is to
intercept
as
recovertToSucceededIf
is to assertThrows
. The first one allows you to
perform further assertions on the expected exception. The second one gives you a result type that will satisfy the type checker
at the end of the test body. Here's an example showing recoverToExceptionIf
in the REPL:
scala> val futureEx = | recoverToExceptionIf[IllegalStateException] { | Future { throw new IllegalStateException("hello") } | } futureEx: scala.concurrent.Future[IllegalStateException] = ... scala> futureEx.value res6: Option[scala.util.Try[IllegalStateException]] = Some(Success(java.lang.IllegalStateException: hello)) scala> futureEx map { ex => assert(ex.getMessage == "world") } res7: scala.concurrent.Future[org.scalatest.Assertion] = ... scala> res7.value res8: Option[scala.util.Try[org.scalatest.Assertion]] = Some(Failure(org.scalatest.exceptions.TestFailedException: "[hello]" did not equal "[world]"))
To support the common use case of temporarily disabling a test, with the
good intention of resurrecting the test at a later time, AsyncFreeSpec
adds a method
ignore
to strings that can be used instead of in
to register a test. For example, to temporarily
disable the test with the name "addSoon will eventually compute a sum of passed Ints"
, just
change “in
” into “ignore
,” like this:
package org.scalatest.examples.asyncfreespec.ignore import org.scalatest.freespec.AsyncFreeSpec import scala.concurrent.Future class AddSpec extends AsyncFreeSpec { def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "addSoon" - { "will eventually compute a sum of passed Ints" ignore { val futureSum: Future[Int] = addSoon(1, 2) // You can map assertions onto a Future, then return // the resulting Future[Assertion] to ScalaTest: futureSum map { sum => assert(sum == 3) } } } def addNow(addends: Int*): Int = addends.sum "addNow" - { "will immediately compute a sum of passed Ints" in { val sum: Int = addNow(1, 2) // You can also write synchronous tests. The body // must have result type Assertion: assert(sum == 3) } } }
If you run this version of AddSpec
with:
scala> org.scalatest.run(new AddSpec)
It will run only the second test and report that the first test was ignored:
AddSpec: addSoon - will eventually compute a sum of passed Ints !!! IGNORED !!! addNow - will immediately compute a sum of passed Ints
If you wish to temporarily ignore an entire suite of tests, you can (on the JVM, not Scala.js) annotate the test class with @Ignore
, like this:
package org.scalatest.examples.asyncfreespec.ignoreall import org.scalatest.freespec.AsyncFreeSpec import scala.concurrent.Future import org.scalatest.Ignore @Ignore class AddSpec extends AsyncFreeSpec { def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "addSoon" - { "will eventually compute a sum of passed Ints" in { val futureSum: Future[Int] = addSoon(1, 2) // You can map assertions onto a Future, then return // the resulting Future[Assertion] to ScalaTest: futureSum map { sum => assert(sum == 3) } } } def addNow(addends: Int*): Int = addends.sum "addNow" - { "will immediately compute a sum of passed Ints" in { val sum: Int = addNow(1, 2) // You can also write synchronous tests. The body // must have result type Assertion: assert(sum == 3) } } }
When you mark a test class with a tag annotation, ScalaTest will mark each test defined in that class with that tag.
Thus, marking the AddSpec
in the above example with the @Ignore
tag annotation means that both tests
in the class will be ignored. If you run the above AddSpec
in the Scala interpreter, you'll see:
AddSpec: addSoon - will eventually compute a sum of passed Ints !!! IGNORED !!! addNow - will immediately compute a sum of passed Ints !!! IGNORED !!!
Note that marking a test class as ignored won't prevent it from being discovered by ScalaTest. Ignored classes
will be discovered and run, and all their tests will be reported as ignored. This is intended to keep the ignored
class visible, to encourage the developers to eventually fix and “un-ignore” it. If you want to
prevent a class from being discovered at all (on the JVM, not Scala.js), use the DoNotDiscover
annotation instead.
If you want to ignore all tests of a suite on Scala.js, where annotations can't be inspected at runtime, you'll need
to change it
to ignore
at each test site. To make a suite non-discoverable on Scala.js, ensure it
does not declare a public no-arg constructor. You can either declare a public constructor that takes one or more
arguments, or make the no-arg constructor non-public. Because this technique will also make the suite non-discoverable
on the JVM, it is a good approach for suites you want to run (but not be discoverable) on both Scala.js and the JVM.
One of the parameters to AsyncFreeSpec
's run
method is a Reporter
, which
will collect and report information about the running suite of tests.
Information about suites and tests that were run, whether tests succeeded or failed,
and tests that were ignored will be passed to the Reporter
as the suite runs.
Most often the reporting done by default by AsyncFreeSpec
's methods will be sufficient, but
occasionally you may wish to provide custom information to the Reporter
from a test.
For this purpose, an Informer
that will forward information to the current Reporter
is provided via the info
parameterless method.
You can pass the extra information to the Informer
via its apply
method.
The Informer
will then pass the information to the Reporter
via an InfoProvided
event.
One use case for the Informer
is to pass more information about a specification to the reporter. For example,
the GivenWhenThen
trait provides methods that use the implicit info
provided by AsyncFreeSpec
to pass such information to the reporter. Here's an example:
package org.scalatest.examples.asyncfreespec.info import collection.mutable import org.scalatest._ class SetSpec extends freespec.AsyncFreeSpec with GivenWhenThen { "A mutable Set" - { "should allow an element to be added" in { Given("an empty mutable Set") val set = mutable.Set.empty[String] When("an element is added") set += "clarity" Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains("clarity")) info("That's all folks!") succeed } } }
If you run this AsyncFreeSpec
from the interpreter, you will see the following output:
scala> org.scalatest.run(new SetSpec)
A mutable Set
- should allow an element to be added
+ Given an empty mutable Set
+ When an element is added
+ Then the Set should have size 1
+ And the Set should contain the added element
+ That's all folks!
AsyncFreeSpec
also provides a markup
method that returns a Documenter
, which allows you to send
to the Reporter
text formatted in Markdown syntax.
You can pass the extra information to the Documenter
via its apply
method.
The Documenter
will then pass the information to the Reporter
via an MarkupProvided
event.
Here's an example AsyncFreeSpec
that uses markup
:
package org.scalatest.examples.asyncfreespec.markup import collection.mutable import org.scalatest._ class SetSpec extends freespec.AsyncFreeSpec with GivenWhenThen { markup { """ Mutable Set ----------- A set is a collection that contains no duplicate elements. To implement a concrete mutable set, you need to provide implementations of the following methods: def contains(elem: A): Boolean def iterator: Iterator[A] def += (elem: A): this.type def -= (elem: A): this.type If you wish that methods like `take`, `drop`, `filter` return the same kind of set, you should also override: def empty: This It is also good idea to override methods `foreach` and `size` for efficiency. """ } "A mutable Set" - { "should allow an element to be added" in { Given("an empty mutable Set") val set = mutable.Set.empty[String] When("an element is added") set += "clarity" Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains("clarity")) markup("This test finished with a **bold** statement!") succeed } } }
Although all of ScalaTest's built-in reporters will display the markup text in some form,
the HTML reporter will format the markup information into HTML. Thus, the main purpose of markup
is to
add nicely formatted text to HTML reports. Here's what the above SetSpec
would look like in the HTML reporter:
ScalaTest records text passed to info
and markup
during tests, and sends the recorded text in the recordedEvents
field of
test completion events like TestSucceeded
and TestFailed
. This allows string reporters (like the standard out reporter) to show
info
and markup
text after the test name in a color determined by the outcome of the test. For example, if the test fails, string
reporters will show the info
and markup
text in red. If a test succeeds, string reporters will show the info
and markup
text in green. While this approach helps the readability of reports, it means that you can't use info
to get status
updates from long running tests.
To get immediate (i.e., non-recorded) notifications from tests, you can use note
(a Notifier
) and alert
(an Alerter
). Here's an example showing the differences:
package org.scalatest.examples.asyncfreespec.note import collection.mutable import org.scalatest._ class SetSpec extends freespec.AsyncFreeSpec { "A mutable Set" - { "should allow an element to be added" in { info("info is recorded") markup("markup is *also* recorded") note("notes are sent immediately") alert("alerts are also sent immediately") val set = mutable.Set.empty[String] set += "clarity" assert(set.size === 1) assert(set.contains("clarity")) } } }
scala> org.scalatest.run(new SetSpec) SetSpec: A mutable Set + notes are sent immediately + alerts are also sent immediately - should allow an element to be added + info is recorded + markup is *also* recorded
Another example is slowpoke notifications.
If you find a test is taking a long time to complete, but you're not sure which test, you can enable
slowpoke notifications. ScalaTest will use an Alerter
to fire an event whenever a test has been running
longer than a specified amount of time.
In summary, use info
and markup
for text that should form part of the specification output. Use
note
and alert
to send status notifications. (Because the HTML reporter is intended to produce a
readable, printable specification, info
and markup
text will appear in the HTML report, but
note
and alert
text will not.)
A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.
To support this style of testing, a test can be given a name that specifies one
bit of behavior required by the system being tested. At the end of the test,
it can call method pending
, which will cause it to complete abruptly with TestPendingException
.
Because tests in ScalaTest can be designated as pending with TestPendingException
, both the test name and any information
sent to the reporter when running the test can appear in the report of a test run. (In other words,
the code of a pending test is executed just like any other test.) However, because the test completes abruptly
with TestPendingException
, the test will be reported as pending, to indicate
the actual test, and possibly the functionality, has not yet been implemented. Here's an example:
package org.scalatest.examples.asyncfreespec.pending import org.scalatest.freespec.AsyncFreeSpec import scala.concurrent.Future class AddSpec extends AsyncFreeSpec { def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "addSoon" - { "will eventually compute a sum of passed Ints" in (pending) } def addNow(addends: Int*): Int = addends.sum "addNow" - { "will immediately compute a sum of passed Ints" in { val sum: Int = addNow(1, 2) // You can also write synchronous tests. The body // must have result type Assertion: assert(sum == 3) } } }
(Note: "(pending)
" is the body of the test. Thus the test contains just one statement, an invocation
of the pending
method, which throws TestPendingException
.)
If you run this version of AddSpec
with:
scala> org.scalatest.run(new AddSpec)
It will run both tests, but report that first test is pending. You'll see:
AddSpec: addSoon - will eventually compute a sum of passed Ints (pending) addNow - will immediately compute a sum of passed Ints
One difference between an ignored test and a pending one is that an ignored test is intended to be used during significant refactorings of the code under test, when tests break and you don't want to spend the time to fix all of them immediately. You can mark some of those broken tests as ignored temporarily, so that you can focus the red bar on just failing tests you actually want to fix immediately. Later you can go back and fix the ignored tests. In other words, by ignoring some failing tests temporarily, you can more easily notice failed tests that you actually want to fix. By contrast, a pending test is intended to be used before a test and/or the code under test is written. Pending indicates you've decided to write a test for a bit of behavior, but either you haven't written the test yet, or have only written part of it, or perhaps you've written the test but don't want to implement the behavior it tests until after you've implemented a different bit of behavior you realized you need first. Thus ignored tests are designed to facilitate refactoring of existing code whereas pending tests are designed to facilitate the creation of new code.
One other difference between ignored and pending tests is that ignored tests are implemented as a test tag that is
excluded by default. Thus an ignored test is never executed. By contrast, a pending test is implemented as a
test that throws TestPendingException
(which is what calling the pending
method does). Thus
the body of pending tests are executed up until they throw TestPendingException
.
An AsyncFreeSpec
's tests may be classified into groups by tagging them with string names.
As with any suite, when executing an AsyncFreeSpec
, groups of tests can
optionally be included and/or excluded. To tag an AsyncFreeSpec
's tests,
you pass objects that extend class org.scalatest.Tag
to methods
that register tests. Class Tag
takes one parameter, a string name. If you have
created tag annotation interfaces as described in the Tag
documentation, then you
will probably want to use tag names on your test functions that match. To do so, simply
pass the fully qualified names of the tag interfaces to the Tag
constructor. For example, if you've
defined a tag annotation interface with fully qualified name,
com.mycompany.tags.DbTest
, then you could
create a matching tag for AsyncFreeSpec
s like this:
package org.scalatest.examples.asyncfreespec.tagging import org.scalatest.Tag object DbTest extends Tag("com.mycompany.tags.DbTest")
Given these definitions, you could place AsyncFreeSpec
tests into groups with tags like this:
import org.scalatest.freespec.AsyncFreeSpec import org.scalatest.tagobjects.Slow import scala.concurrent.Future class AddSpec extends AsyncFreeSpec { def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "addSoon" - { "will eventually compute a sum of passed Ints" taggedAs(Slow) in { val futureSum: Future[Int] = addSoon(1, 2) // You can map assertions onto a Future, then return // the resulting Future[Assertion] to ScalaTest: futureSum map { sum => assert(sum == 3) } } } def addNow(addends: Int*): Int = addends.sum "addNow" - { "will immediately compute a sum of passed Ints" taggedAs(Slow, DbTest) in { val sum: Int = addNow(1, 2) // You can also write synchronous tests. The body // must have result type Assertion: assert(sum == 3) } } }
This code marks both tests with the org.scalatest.tags.Slow
tag,
and the second test with the com.mycompany.tags.DbTest
tag.
The run
method takes a Filter
, whose constructor takes an optional
Set[String]
called tagsToInclude
and a Set[String]
called
tagsToExclude
. If tagsToInclude
is None
, all tests will be run
except those those belonging to tags listed in the
tagsToExclude
Set
. If tagsToInclude
is defined, only tests
belonging to tags mentioned in the tagsToInclude
set, and not mentioned in tagsToExclude
,
will be run.
It is recommended, though not required, that you create a corresponding tag annotation when you
create a Tag
object. A tag annotation (on the JVM, not Scala.js) allows you to tag all the tests of an AsyncFreeSpec
in
one stroke by annotating the class. For more information and examples, see the
documentation for class Tag
. On Scala.js, to tag all tests of a suite, you'll need to
tag each test individually at the test site.
== Shared fixtures ==
A test fixture is composed of the objects and other artifacts (files, sockets, database connections, etc.) tests use to do their work. When multiple tests need to work with the same fixtures, it is important to try and avoid duplicating the fixture code across those tests. The more code duplication you have in your tests, the greater drag the tests will have on refactoring the actual production code.
ScalaTest recommends three techniques to eliminate such code duplication in async styles:
-
Refactor using Scala
-
Override
withFixture
-
Mix in a before-and-after trait
Each technique is geared towards helping you reduce code duplication without introducing
instance var
s, shared mutable objects, or other dependencies between tests. Eliminating shared
mutable state across tests will make your test code easier to reason about and eliminate the need to
synchronize access to shared mutable state on the JVM.
The following sections describe these techniques, including explaining the recommended usage for each. But first, here's a table summarizing the options:
Refactor using Scala when different tests need different fixtures. | |
get-fixture methods | The extract method refactor helps you create a fresh instances of mutable fixture objects in each test that needs them, but doesn't help you clean them up when you're done. |
loan-fixture methods | Factor out dupicate code with the loan pattern when different tests need different fixtures that must be cleaned up afterwards. |
Override withFixture when most or all tests need the same fixture.
|
|
withFixture(NoArgAsyncTest)
|
The recommended default approach when most or all tests need the same fixture treatment. This general technique allows you, for example, to perform side effects at the beginning and end of all or most tests, transform the outcome of tests, retry tests, make decisions based on test names, tags, or other test data. Use this technique unless:
|
withFixture(OneArgAsyncTest)
|
Use when you want to pass the same fixture object or objects as a parameter into all or most tests. |
Mix in a before-and-after trait when you want an aborted suite, not a failed test, if the fixture code fails. | |
BeforeAndAfter
|
Use this boilerplate-buster when you need to perform the same side-effects before and/or after tests, rather than at the beginning or end of tests. |
BeforeAndAfterEach
|
Use when you want to stack traits that perform the same side-effects before and/or after tests, rather than at the beginning or end of tests. |
==== Calling get-fixture methods ====
If you need to create the same mutable fixture objects in multiple tests, and don't need to clean them up after using them, the simplest approach is to write one or more get-fixture methods. A get-fixture method returns a new instance of a needed fixture object (or a holder object containing multiple fixture objects) each time it is called. You can call a get-fixture method at the beginning of each test that needs the fixture, storing the returned object or objects in local variables. Here's an example:
package org.scalatest.examples.asyncfreespec.getfixture import org.scalatest.freespec.AsyncFreeSpec import scala.concurrent.Future class ExampleSpec extends AsyncFreeSpec { def fixture: Future[String] = Future { "ScalaTest is " } "Testing" - { "should be easy" in { val future = fixture val result = future map { s => s + "easy!" } result map { s => assert(s == "ScalaTest is easy!") } } "should be fun" in { val future = fixture val result = future map { s => s + "fun!" } result map { s => assert(s == "ScalaTest is fun!") } } } }
If you need to configure fixture objects differently in different tests, you can pass configuration into the get-fixture method. For example, you could pass in an initial value for a fixture object as a parameter to the get-fixture method.
==== Overriding withFixture(NoArgAsyncTest)
====
Although the get-fixture method approach takes care of setting up a fixture at the beginning of each
test, it doesn't address the problem of cleaning up a fixture at the end of the test. If you just need to perform a side-effect at the beginning or end of
a test, and don't need to actually pass any fixture objects into the test, you can override withFixture(NoArgAsyncTest)
, a
method defined in trait AsyncTestSuite
, a supertrait of AsyncFreeSpec
.
Trait AsyncFreeSpec
's runTest
method passes a no-arg async test function to
withFixture(NoArgAsyncTest)
. It is withFixture
's
responsibility to invoke that test function. The default implementation of withFixture
simply
invokes the function and returns the result, like this:
// Default implementation in trait AsyncTestSuite protected def withFixture(test: NoArgAsyncTest): FutureOutcome = { test() }
You can, therefore, override withFixture
to perform setup before invoking the test function,
and/or perform cleanup after the test completes. The recommended way to ensure cleanup is performed after a test completes is
to use the complete
-lastly
syntax, defined in supertrait CompleteLastly
.
The complete
-lastly
syntax will ensure that
cleanup will occur whether future-producing code completes abruptly by throwing an exception, or returns
normally yielding a future. In the latter case, complete
-lastly
will register the cleanup code
to execute asynchronously when the future completes.
The withFixture
method is designed to be stacked, and to enable this, you should always call the super
implementation
of withFixture
, and let it invoke the test function rather than invoking the test function directly. In other words, instead of writing
“test()
”, you should write “super.withFixture(test)
”, like this:
// Your implementation override def withFixture(test: NoArgAsyncTest) = { // Perform setup here complete { super.withFixture(test) // Invoke the test function } lastly { // Perform cleanup here } }
If you have no cleanup to perform, you can write withFixture
like this instead:
// Your implementation override def withFixture(test: NoArgAsyncTest) = { // Perform setup here super.withFixture(test) // Invoke the test function }
If you want to perform an action only for certain outcomes, you'll need to
register code performing that action as a callback on the Future
using
one of Future
's registration methods: onComplete
, onSuccess
,
or onFailure
. Note that if a test fails, that will be treated as a
scala.util.Success(org.scalatest.Failed)
. So if you want to perform an
action if a test fails, for example, you'd register the callback using onSuccess
.
Here's an example in which withFixture(NoArgAsyncTest)
is used to take a
snapshot of the working directory if a test fails, and
send that information to the standard output stream:
package org.scalatest.examples.asyncfreespec.noargasynctest import java.io.File import org.scalatest._ import scala.concurrent.Future class ExampleSpec extends freespec.AsyncFreeSpec { override def withFixture(test: NoArgAsyncTest) = { super.withFixture(test) onFailedThen { _ => val currDir = new File(".") val fileNames = currDir.list() info("Dir snapshot: " + fileNames.mkString(", ")) } } def addSoon(addends: Int*): Future[Int] = Future { addends.sum } "This test" - { "should succeed" in { addSoon(1, 1) map { sum => assert(sum == 2) } } "should fail" in { addSoon(1, 1) map { sum => assert(sum == 3) } } } }
Running this version of ExampleSpec
in the interpreter in a directory with two files, hello.txt
and world.txt
would give the following output:
scala> org.scalatest.run(new ExampleSpec) ExampleSpec: This test - should succeed - should fail *** FAILED *** 2 did not equal 3 (:33)
Note that the NoArgAsyncTest
passed to withFixture
, in addition to
an apply
method that executes the test, also includes the test name and the config
map passed to runTest
. Thus you can also use the test name and configuration objects in your withFixture
implementation.
Lastly, if you want to transform the outcome in some way in withFixture
, you'll need to use either the
map
or transform
methods of Future
, like this:
// Your implementation override def withFixture(test: NoArgAsyncTest) = { // Perform setup here val futureOutcome = super.withFixture(test) // Invoke the test function futureOutcome change { outcome => // transform the outcome into a new outcome here } }
Note that a NoArgAsyncTest
's apply
method will return a scala.util.Failure
only if
the test completes abruptly with a "test-fatal" exception (such as OutOfMemoryError
) that should
cause the suite to abort rather than the test to fail. Thus usually you would use map
to transform future outcomes, not transform
, so that such test-fatal exceptions pass through
unchanged. The suite will abort asynchronously with any exception returned from NoArgAsyncTest
's
apply method in a scala.util.Failure
.
==== Calling loan-fixture methods ====
If you need to both pass a fixture object into a test and perform cleanup at the end of the test, you'll need to use the loan pattern. If different tests need different fixtures that require cleanup, you can implement the loan pattern directly by writing loan-fixture methods. A loan-fixture method takes a function whose body forms part or all of a test's code. It creates a fixture, passes it to the test code by invoking the function, then cleans up the fixture after the function returns.
The following example shows three tests that use two fixtures, a database and a file. Both require cleanup after, so each is provided via a
loan-fixture method. (In this example, the database is simulated with a StringBuffer
.)
package org.scalatest.examples.asyncfreespec.loanfixture import java.util.concurrent.ConcurrentHashMap import scala.concurrent.Future import scala.concurrent.ExecutionContext object DbServer { // Simulating a database server type Db = StringBuffer private final val databases = new ConcurrentHashMap[String, Db] def createDb(name: String): Db = { val db = new StringBuffer // java.lang.StringBuffer is thread-safe databases.put(name, db) db } def removeDb(name: String): Unit = { databases.remove(name) } } // Defining actor messages sealed abstract class StringOp case object Clear extends StringOp case class Append(value: String) extends StringOp case object GetValue class StringActor { // Simulating an actor private final val sb = new StringBuilder def !(op: StringOp): Unit = synchronized { op match { case Append(value) => sb.append(value) case Clear => sb.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] = Future { synchronized { sb.toString } } } import org.scalatest._ import DbServer._ import java.util.UUID.randomUUID class ExampleSpec extends freespec.AsyncFreeSpec { def withDatabase(testCode: Future[Db] => Future[Assertion]) = { val dbName = randomUUID.toString // generate a unique db name val futureDb = Future { createDb(dbName) } // create the fixture complete { val futurePopulatedDb = futureDb map { db => db.append("ScalaTest is ") // perform setup } testCode(futurePopulatedDb) // "loan" the fixture to the test code } lastly { removeDb(dbName) // ensure the fixture will be cleaned up } } def withActor(testCode: StringActor => Future[Assertion]) = { val actor = new StringActor complete { actor ! Append("ScalaTest is ") // set up the fixture testCode(actor) // "loan" the fixture to the test code } lastly { actor ! Clear // ensure the fixture will be cleaned up } } "Testing" - { // This test needs the actor fixture "should be productive" in { withActor { actor => actor ! Append("productive!") val futureString = actor ? GetValue futureString map { s => assert(s == "ScalaTest is productive!") } } } } "Test code" - { // This test needs the database fixture "should be readable" in { withDatabase { futureDb => futureDb map { db => db.append("readable!") assert(db.toString == "ScalaTest is readable!") } } } // This test needs both the actor and the database "should be clear and concise" in { withDatabase { futureDb => withActor { actor => // loan-fixture methods compose actor ! Append("concise!") val futureString = actor ? GetValue val futurePair: Future[(Db, String)] = futureDb zip futureString futurePair map { case (db, s) => db.append("clear!") assert(db.toString == "ScalaTest is clear!") assert(s == "ScalaTest is concise!") } } } } } }
As demonstrated by the last test, loan-fixture methods compose. Not only do loan-fixture methods allow you to give each test the fixture it needs, they allow you to give a test multiple fixtures and clean everything up afterwards.
Also demonstrated in this example is the technique of giving each test its own "fixture sandbox" to play in. When your fixtures involve external side-effects, like creating databases, it is a good idea to give each database a unique name as is done in this example. This keeps tests completely isolated, allowing you to run them in parallel if desired.
==== Overriding withFixture(OneArgTest)
====
If all or most tests need the same fixture, you can avoid some of the boilerplate of the loan-fixture method approach by using a
FixtureAsyncTestSuite
and overriding withFixture(OneArgAsyncTest)
.
Each test in a FixtureAsyncTestSuite
takes a fixture as a parameter, allowing you to pass the fixture into
the test. You must indicate the type of the fixture parameter by specifying FixtureParam
, and implement a
withFixture
method that takes a OneArgAsyncTest
. This withFixture
method is responsible for
invoking the one-arg async test function, so you can perform fixture set up before invoking and passing
the fixture into the test function, and ensure clean up is performed after the test completes.
To enable the stacking of traits that define withFixture(NoArgAsyncTest)
, it is a good idea to let
withFixture(NoArgAsyncTest)
invoke the test function instead of invoking the test
function directly. To do so, you'll need to convert the OneArgAsyncTest
to a NoArgAsyncTest
. You can do that by passing
the fixture object to the toNoArgAsyncTest
method of OneArgAsyncTest
. In other words, instead of
writing “test(theFixture)
”, you'd delegate responsibility for
invoking the test function to the withFixture(NoArgAsyncTest)
method of the same instance by writing:
withFixture(test.toNoArgAsyncTest(theFixture))
Here's a complete example:
package org.scalatest.examples.asyncfreespec.oneargasynctest import org.scalatest._ import scala.concurrent.Future import scala.concurrent.ExecutionContext // Defining actor messages sealed abstract class StringOp case object Clear extends StringOp case class Append(value: String) extends StringOp case object GetValue class StringActor { // Simulating an actor private final val sb = new StringBuilder def !(op: StringOp): Unit = synchronized { op match { case Append(value) => sb.append(value) case Clear => sb.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] = Future { synchronized { sb.toString } } } class ExampleSpec extends freespec.FixtureAsyncFreeSpec { type FixtureParam = StringActor def withFixture(test: OneArgAsyncTest): FutureOutcome = { val actor = new StringActor complete { actor ! Append("ScalaTest is ") // set up the fixture withFixture(test.toNoArgAsyncTest(actor)) } lastly { actor ! Clear // ensure the fixture will be cleaned up } } "Testing" - { "should be easy" in { actor => actor ! Append("easy!") val futureString = actor ? GetValue futureString map { s => assert(s == "ScalaTest is easy!") } } "should be fun" in { actor => actor ! Append("fun!") val futureString = actor ? GetValue futureString map { s => assert(s == "ScalaTest is fun!") } } } }
In this example, the tests required one fixture object, a StringActor
. If your tests need multiple fixture objects, you can
simply define the FixtureParam
type to be a tuple containing the objects or, alternatively, a case class containing
the objects. For more information on the withFixture(OneArgAsyncTest)
technique, see
the documentation for FixtureAsyncFreeSpec
.
==== Mixing in BeforeAndAfter
====
In all the shared fixture examples shown so far, the activities of creating, setting up, and cleaning up the fixture objects have been
performed during the test. This means that if an exception occurs during any of these activities, it will be reported as a test failure.
Sometimes, however, you may want setup to happen before the test starts, and cleanup after the test has completed, so that if an
exception occurs during setup or cleanup, the entire suite aborts and no more tests are attempted. The simplest way to accomplish this in ScalaTest is
to mix in trait BeforeAndAfter
. With this trait you can denote a bit of code to run before each test
with before
and/or after each test each test with after
, like this:
package org.scalatest.examples.asyncfreespec.beforeandafter import org.scalatest.freespec.AsyncFreeSpec import org.scalatest.BeforeAndAfter import scala.concurrent.Future import scala.concurrent.ExecutionContext // Defining actor messages sealed abstract class StringOp case object Clear extends StringOp case class Append(value: String) extends StringOp case object GetValue class StringActor { // Simulating an actor private final val sb = new StringBuilder def !(op: StringOp): Unit = synchronized { op match { case Append(value) => sb.append(value) case Clear => sb.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] = Future { synchronized { sb.toString } } } class ExampleSpec extends AsyncFreeSpec with BeforeAndAfter { final val actor = new StringActor before { actor ! Append("ScalaTest is ") // set up the fixture } after { actor ! Clear // clean up the fixture } "Testing" - { "should be easy" in { actor ! Append("easy!") val futureString = actor ? GetValue futureString map { s => assert(s == "ScalaTest is easy!") } } "should be fun" in { actor ! Append("fun!") val futureString = actor ? GetValue futureString map { s => assert(s == "ScalaTest is fun!") } } } }
Note that the only way before
and after
code can communicate with test code is via some
side-effecting mechanism, commonly by reassigning instance var
s or by changing the state of mutable
objects held from instance val
s (as in this example). If using instance var
s or
mutable objects held from instance val
s you wouldn't be able to run tests in parallel in the same instance
of the test class (on the JVM, not Scala.js) unless you synchronized access to the shared, mutable state.
Note that on the JVM, if you override ScalaTest's default
serial execution context, you will likely need to
worry about synchronizing access to shared mutable fixture state, because the execution
context may assign different threads to process
different Future
transformations. Although access to mutable state along
the same linear chain of Future
transformations need not be synchronized,
it can be difficult to spot cases where these constraints are violated. The best approach
is to use only immutable objects when transforming Future
s. When that's not
practical, involve only thread-safe mutable objects, as is done in the above example.
On Scala.js, by contrast, you need not worry about thread synchronization, because
in effect only one thread exists.
Although BeforeAndAfter
provides a minimal-boilerplate way to execute code before and after tests, it isn't designed to enable stackable
traits, because the order of execution would be non-obvious. If you want to factor out before and after code that is common to multiple test suites, you
should use trait BeforeAndAfterEach
instead, as shown later in the next section,
composing fixtures by stacking traits.
== Composing fixtures by stacking traits ==
In larger projects, teams often end up with several different fixtures that test classes need in different combinations,
and possibly initialized (and cleaned up) in different orders. A good way to accomplish this in ScalaTest is to factor the individual
fixtures into traits that can be composed using the stackable trait pattern. This can be done, for example, by placing
withFixture
methods in several traits, each of which call super.withFixture
. Here's an example in
which the StringBuilderActor
and StringBufferActor
fixtures used in the previous examples have been
factored out into two stackable fixture traits named Builder
and Buffer
:
package org.scalatest.examples.asyncfreespec.composingwithasyncfixture import org.scalatest._ import org.scalatest.SuiteMixin import collection.mutable.ListBuffer import scala.concurrent.Future import scala.concurrent.ExecutionContext // Defining actor messages sealed abstract class StringOp case object Clear extends StringOp case class Append(value: String) extends StringOp case object GetValue class StringBuilderActor { // Simulating an actor private final val sb = new StringBuilder def !(op: StringOp): Unit = synchronized { op match { case Append(value) => sb.append(value) case Clear => sb.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] = Future { synchronized { sb.toString } } } class StringBufferActor { private final val buf = ListBuffer.empty[String] def !(op: StringOp): Unit = synchronized { op match { case Append(value) => buf += value case Clear => buf.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[List[String]] = Future { synchronized { buf.toList } } } trait Builder extends AsyncTestSuiteMixin { this: AsyncTestSuite => final val builderActor = new StringBuilderActor abstract override def withFixture(test: NoArgAsyncTest) = { builderActor ! Append("ScalaTest is ") complete { super.withFixture(test) // To be stackable, must call super.withFixture } lastly { builderActor ! Clear } } } trait Buffer extends AsyncTestSuiteMixin { this: AsyncTestSuite => final val bufferActor = new StringBufferActor abstract override def withFixture(test: NoArgAsyncTest) = { complete { super.withFixture(test) // To be stackable, must call super.withFixture } lastly { bufferActor ! Clear } } } class ExampleSpec extends freespec.AsyncFreeSpec with Builder with Buffer { "Testing" - { "should be easy" in { builderActor ! Append("easy!") val futureString = builderActor ? GetValue val futureList = bufferActor ? GetValue val futurePair: Future[(String, List[String])] = futureString zip futureList futurePair map { case (str, lst) => assert(str == "ScalaTest is easy!") assert(lst.isEmpty) bufferActor ! Append("sweet") succeed } } "should be fun" in { builderActor ! Append("fun!") val futureString = builderActor ? GetValue val futureList = bufferActor ? GetValue val futurePair: Future[(String, List[String])] = futureString zip futureList futurePair map { case (str, lst) => assert(str == "ScalaTest is fun!") assert(lst.isEmpty) bufferActor ! Append("awesome") succeed } } } }
By mixing in both the Builder
and Buffer
traits, ExampleSpec
gets both fixtures, which will be
initialized before each test and cleaned up after. The order the traits are mixed together determines the order of execution.
In this case, Builder
is “super” to Buffer
. If you wanted Buffer
to be “super”
to Builder
, you need only switch the order you mix them together, like this:
class Example2Spec extends freespec.AsyncFreeSpec with Buffer with Builder
If you only need one fixture you mix in only that trait:
class Example3Spec extends freespec.AsyncFreeSpec with Builder
Another way to create stackable fixture traits is by extending the BeforeAndAfterEach
and/or BeforeAndAfterAll
traits.
BeforeAndAfterEach
has a beforeEach
method that will be run before each test (like JUnit's setUp
),
and an afterEach
method that will be run after (like JUnit's tearDown
).
Similarly, BeforeAndAfterAll
has a beforeAll
method that will be run before all tests,
and an afterAll
method that will be run after all tests. Here's what the previously shown example would look like if it
were rewritten to use the BeforeAndAfterEach
methods instead of withFixture
:
package org.scalatest.examples.asyncfreespec.composingbeforeandaftereach import org.scalatest._ import org.scalatest.BeforeAndAfterEach import collection.mutable.ListBuffer import scala.concurrent.Future import scala.concurrent.ExecutionContext // Defining actor messages sealed abstract class StringOp case object Clear extends StringOp case class Append(value: String) extends StringOp case object GetValue class StringBuilderActor { // Simulating an actor private final val sb = new StringBuilder def !(op: StringOp): Unit = synchronized { op match { case Append(value) => sb.append(value) case Clear => sb.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[String] = Future { synchronized { sb.toString } } } class StringBufferActor { private final val buf = ListBuffer.empty[String] def !(op: StringOp): Unit = synchronized { op match { case Append(value) => buf += value case Clear => buf.clear() } } def ?(get: GetValue.type)(implicit c: ExecutionContext): Future[List[String]] = Future { synchronized { buf.toList } } } trait Builder extends BeforeAndAfterEach { this: Suite => final val builderActor = new StringBuilderActor override def beforeEach() { builderActor ! Append("ScalaTest is ") super.beforeEach() // To be stackable, must call super.beforeEach } override def afterEach() { try super.afterEach() // To be stackable, must call super.afterEach finally builderActor ! Clear } } trait Buffer extends BeforeAndAfterEach { this: Suite => final val bufferActor = new StringBufferActor override def afterEach() { try super.afterEach() // To be stackable, must call super.afterEach finally bufferActor ! Clear } } class ExampleSpec extends freespec.AsyncFreeSpec with Builder with Buffer { "Testing" - { "should be easy" in { builderActor ! Append("easy!") val futureString = builderActor ? GetValue val futureList = bufferActor ? GetValue val futurePair: Future[(String, List[String])] = futureString zip futureList futurePair map { case (str, lst) => assert(str == "ScalaTest is easy!") assert(lst.isEmpty) bufferActor ! Append("sweet") succeed } } "should be fun" in { builderActor ! Append("fun!") val futureString = builderActor ? GetValue val futureList = bufferActor ? GetValue val futurePair: Future[(String, List[String])] = futureString zip futureList futurePair map { case (str, lst) => assert(str == "ScalaTest is fun!") assert(lst.isEmpty) bufferActor ! Append("awesome") succeed } } } }
To get the same ordering as withFixture
, place your super.beforeEach
call at the end of each
beforeEach
method, and the super.afterEach
call at the beginning of each afterEach
method, as shown in the previous example. It is a good idea to invoke super.afterEach
in a try
block and perform cleanup in a finally
clause, as shown in the previous example, because this ensures the
cleanup code is performed even if super.afterEach
throws an exception.
The difference between stacking traits that extend BeforeAndAfterEach
versus traits that implement withFixture
is
that setup and cleanup code happens before and after the test in BeforeAndAfterEach
, but at the beginning and
end of the test in withFixture
. Thus if a withFixture
method completes abruptly with an exception, it is
considered a failed test. By contrast, if any of the beforeEach
or afterEach
methods of BeforeAndAfterEach
complete abruptly, it is considered an aborted suite, which will result in a SuiteAborted
event.
Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared"
by different fixture objects.
To accomplish this in an AsyncFreeSpec
, you first place shared tests in
behavior functions. These behavior functions will be
invoked during the construction phase of any AsyncFreeSpec
that uses them, so that the tests they contain will
be registered as tests in that AsyncFreeSpec
.
For example, given this StackActor
class:
package org.scalatest.examples.asyncfreespec.sharedtests import scala.collection.mutable.ListBuffer import scala.concurrent.Future import scala.concurrent.ExecutionContext // Stack operations case class Push[T](value: T) sealed abstract class StackOp case object Pop extends StackOp case object Peek extends StackOp case object Size extends StackOp // Stack info case class StackInfo[T](top: Option[T], size: Int, max: Int) { require(size > 0, "size was less than zero") require(max >= size, "max was less than size") val isFull: Boolean = size == max val isEmpty: Boolean = size == 0 } class StackActor[T](Max: Int, name: String) { private final val buf = new ListBuffer[T] def !(push: Push[T]): Unit = synchronized { if (buf.size != Max) buf.prepend(push.value) else throw new IllegalStateException("can't push onto a full stack") } def ?(op: StackOp)(implicit c: ExecutionContext): Future[StackInfo[T]] = synchronized { op match { case Pop => Future { if (buf.size != 0) StackInfo(Some(buf.remove(0)), buf.size, Max) else throw new IllegalStateException("can't pop an empty stack") } case Peek => Future { if (buf.size != 0) StackInfo(Some(buf(0)), buf.size, Max) else throw new IllegalStateException("can't peek an empty stack") } case Size => Future { StackInfo(None, buf.size, Max) } } } override def toString: String = name }
You may want to test the stack represented by the StackActor
class in different states: empty, full, with one item, with one item less than capacity,
etc. You may find you have several tests that make sense any time the stack is non-empty. Thus you'd ideally want to run
those same tests for three stack fixture objects: a full stack, a stack with a one item, and a stack with one item less than
capacity. With shared tests, you can factor these tests out into a behavior function, into which you pass the
stack fixture to use when running the tests. So in your AsyncFreeSpec
for StackActor
, you'd invoke the
behavior function three times, passing in each of the three stack fixtures so that the shared tests are run for all three fixtures.
You can define a behavior function that encapsulates these shared tests inside the AsyncFreeSpec
that uses them. If they are shared
between different AsyncFreeSpec
s, however, you could also define them in a separate trait that is mixed into
each AsyncFreeSpec
that uses them.
For example, here the nonEmptyStackActor
behavior function (in this case, a
behavior method) is defined in a trait along with another
method containing shared tests for non-full stacks:
import org.scalatest.freespec.AsyncFreeSpec trait AsyncFreeSpecStackBehaviors { this: AsyncFreeSpec => def nonEmptyStackActor(createNonEmptyStackActor: => StackActor[Int], lastItemAdded: Int, name: String): Unit = { ("return non-empty StackInfo when Size is fired at non-empty stack actor: " + name) in { val stackActor = createNonEmptyStackActor val futureStackInfo = stackActor ? Size futureStackInfo map { stackInfo => assert(!stackInfo.isEmpty) } } ("return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: " + name) in { val stackActor = createNonEmptyStackActor val futurePair: Future[(StackInfo[Int], StackInfo[Int])] = for { beforePeek <- stackActor ? Size afterPeek <- stackActor ? Peek } yield (beforePeek, afterPeek) futurePair map { case (beforePeek, afterPeek) => assert(afterPeek.top == Some(lastItemAdded)) assert(afterPeek.size == beforePeek.size) } } ("return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: " + name) in { val stackActor = createNonEmptyStackActor val futurePair: Future[(StackInfo[Int], StackInfo[Int])] = for { beforePop <- stackActor ? Size afterPop <- stackActor ? Pop } yield (beforePop, afterPop) futurePair map { case (beforePop, afterPop) => assert(afterPop.top == Some(lastItemAdded)) assert(afterPop.size == beforePop.size - 1) } } } def nonFullStackActor(createNonFullStackActor: => StackActor[Int], name: String): Unit = { ("return non-full StackInfo when Size is fired at non-full stack actor: " + name) in { val stackActor = createNonFullStackActor val futureStackInfo = stackActor ? Size futureStackInfo map { stackInfo => assert(!stackInfo.isFull) } } ("return before and after StackInfo that has existing size + 1 and new item as top when Push is fired at non-full stack actor: " + name) in { val stackActor = createNonFullStackActor val futurePair: Future[(StackInfo[Int], StackInfo[Int])] = for { beforePush <- stackActor ? Size afterPush <- { stackActor ! Push(7); stackActor ? Peek } } yield (beforePush, afterPush) futurePair map { case (beforePush, afterPush) => assert(afterPush.top == Some(7)) assert(afterPush.size == beforePush.size + 1) } } } }
Given these behavior functions, you could invoke them directly, but AsyncFreeSpec
offers a DSL for the purpose,
which looks like this:
behave like nonEmptyStackActor(almostEmptyStackActor, LastValuePushed, almostEmptyStackActorName)
Here's an example:
class StackSpec extends AsyncFreeSpec with AsyncFreeSpecStackBehaviors { val Max = 10 val LastValuePushed = Max - 1 // Stack fixture creation methods val emptyStackActorName = "empty stack actor" def emptyStackActor = new StackActor[Int](Max, emptyStackActorName ) val fullStackActorName = "full stack actor" def fullStackActor = { val stackActor = new StackActor[Int](Max, fullStackActorName ) for (i <- 0 until Max) stackActor ! Push(i) stackActor } val almostEmptyStackActorName = "almost empty stack actor" def almostEmptyStackActor = { val stackActor = new StackActor[Int](Max, almostEmptyStackActorName ) stackActor ! Push(LastValuePushed) stackActor } val almostFullStackActorName = "almost full stack actor" def almostFullStackActor = { val stackActor = new StackActor[Int](Max, almostFullStackActorName) for (i <- 1 to LastValuePushed) stackActor ! Push(i) stackActor } "A Stack" - { "(when empty)" - { "should be empty" in { val stackActor = emptyStackActor val futureStackInfo = stackActor ? Size futureStackInfo map { stackInfo => assert(stackInfo.isEmpty) } } "should complain on peek" in { recoverToSucceededIf[IllegalStateException] { emptyStackActor ? Peek } } "should complain on pop" in { recoverToSucceededIf[IllegalStateException] { emptyStackActor ? Pop } } } "(with one item)" - { "should" - { behave like nonEmptyStackActor(almostEmptyStackActor, LastValuePushed, almostEmptyStackActorName) behave like nonFullStackActor(almostEmptyStackActor, almostEmptyStackActorName) } } "(with one item less than capacity)" - { "should" - { behave like nonEmptyStackActor(almostFullStackActor, LastValuePushed, almostFullStackActorName) behave like nonFullStackActor(almostFullStackActor, almostFullStackActorName) } } "(full)" - { "should be full" in { val stackActor = fullStackActor val futureStackInfo = stackActor ? Size futureStackInfo map { stackInfo => assert(stackInfo.isFull) } } "should" - { behave like nonEmptyStackActor(fullStackActor, LastValuePushed, fullStackActorName) } "should complain on a push" in { val stackActor = fullStackActor assertThrows[IllegalStateException] { stackActor ! Push(10) } } } } }
If you load these classes into the Scala interpreter (with scalatest's JAR file on the class path), and execute it, you'll see:
scala> org.scalatest.run(new StackSpec)
StackSpec:
A Stack
(when empty)
- should be empty
- should complain on peek
- should complain on pop
(with one item)
should
- return non-empty StackInfo when Size is fired at non-empty stack actor: almost empty stack actor
- return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: almost empty stack actor
- return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: almost empty stack actor
- return non-full StackInfo when Size is fired at non-full stack actor: almost empty stack actor
- return before and after StackInfo that has existing size + 1 and new item as top when Push is fired at non-full stack actor: almost empty stack actor
(with one item less than capacity)
should
- return non-empty StackInfo when Size is fired at non-empty stack actor: almost full stack actor
- return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: almost full stack actor
- return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: almost full stack actor
- return non-full StackInfo when Size is fired at non-full stack actor: almost full stack actor
- return before and after StackInfo that has existing size + 1 and new item as top when Push is fired at non-full stack actor: almost full stack actor
(full)
- should be full
should
- return non-empty StackInfo when Size is fired at non-empty stack actor: full stack actor
- return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: full stack actor
- return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: full stack actor
- should complain on a push
One thing to keep in mind when using shared tests is that in ScalaTest, each test in a suite must have a unique name.
If you register the same tests repeatedly in the same suite, one problem you may encounter is an exception at runtime
complaining that multiple tests are being registered with the same test name.
Although in an AsyncFreeSpec
, the -
clause is a nesting construct analogous to
AsyncFunSpec
's describe
clause, you many sometimes need to do a bit of
extra work to ensure that the test names are unique. If a duplicate test name problem shows up in an
AsyncFreeSpec
, you'll need to pass in a prefix or suffix string to add to each test name. You can call
toString
on the shared fixture object, or pass this string
the same way you pass any other data needed by the shared tests.
This is the approach taken by the previous AsyncFreeSpecStackBehaviors
example.
Given this AsyncFreeSpecStackBehaviors
trait, calling it with the almostEmptyStackActor
fixture, like this:
behave like nonEmptyStackActor(almostEmptyStackActor, LastValuePushed, almostEmptyStackActorName)
yields test names:
-
A Stack (when non-empty) should return non-empty StackInfo when Size is fired at non-empty stack actor: almost empty stack actor
-
A Stack (when non-empty) should return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: almost empty stack actor
-
A Stack (when non-empty) should return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: almost empty stack actor
Whereas calling it with the almostFullStackActor
fixture, like this:
behave like nonEmptyStackActor(almostFullStackActor, LastValuePushed, almostFullStackActorName)
yields different test names:
-
A Stack (when non-empty) should return non-empty StackInfo when Size is fired at non-empty stack actor: almost full stack actor
-
A Stack (when non-empty) should return before and after StackInfo that has existing size and lastItemAdded as top when Peek is fired at non-empty stack actor: almost full stack actor
-
A Stack (when non-empty) should return before and after StackInfo that has existing size - 1 and lastItemAdded as top when Pop is fired at non-empty stack actor: almost full stack actor
Type members
Inherited classlikes
Class used via an implicit conversion to enable two objects to be compared with
===
and !==
with a Boolean
result and an enforced type constraint between
two object types. For example:
Class used via an implicit conversion to enable two objects to be compared with
===
and !==
with a Boolean
result and an enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
- Value parameters:
- leftSide
An object to convert to
Equalizer
, which represents the value on the left side of a===
or!==
invocation.
- Inherited from:
- TripleEqualsSupport
Class used via an implicit conversion to enable any two objects to be compared with
===
and !==
with a Boolean
result and no enforced type constraint between
two object types. For example:
Class used via an implicit conversion to enable any two objects to be compared with
===
and !==
with a Boolean
result and no enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
- Value parameters:
- leftSide
An object to convert to
Equalizer
, which represents the value on the left side of a===
or!==
invocation.
- Inherited from:
- TripleEqualsSupport
A class that via an implicit conversion (named convertToFreeSpecStringWrapper
) enables
methods in
, is
, taggedAs
and ignore
,
as well as the dash operator (-
), to be invoked on String
s.
A class that via an implicit conversion (named convertToFreeSpecStringWrapper
) enables
methods in
, is
, taggedAs
and ignore
,
as well as the dash operator (-
), to be invoked on String
s.
- Inherited from:
- AsyncFreeSpecLike
A test function taking no arguments and returning a FutureOutcome
.
A test function taking no arguments and returning a FutureOutcome
.
For more detail and examples, see the relevant section in the
documentation for trait AsyncFlatSpec
.
- Inherited from:
- AsyncTestSuite
Class that provides the lastly
method of the complete
-lastly
syntax.
Class that provides the lastly
method of the complete
-lastly
syntax.
- Value parameters:
- futuristic
the futuristic typeclass instance
- futuristicBlock
a by-name that produces a futuristic type
- Inherited from:
- CompleteLastly
Class that supports the registration of tagged tests.
Class that supports the registration of tagged tests.
Instances of this class are returned by the taggedAs
method of
class FreeSpecStringWrapper
.
- Inherited from:
- AsyncFreeSpecLike
Value members
Concrete methods
Returns a user friendly string for this suite, composed of the
simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite
contains nested suites, the result of invoking toString
on each
of the nested suites, separated by commas and surrounded by parentheses.
Returns a user friendly string for this suite, composed of the
simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite
contains nested suites, the result of invoking toString
on each
of the nested suites, separated by commas and surrounded by parentheses.
- Returns:
a user-friendly string for this suite
- Definition Classes
- Any
Inherited methods
Returns a TripleEqualsInvocationOnSpread[T]
, given an Spread[T]
, to facilitate
the “<left> should !== (<pivot> +- <tolerance>)
”
syntax of Matchers
.
Returns a TripleEqualsInvocationOnSpread[T]
, given an Spread[T]
, to facilitate
the “<left> should !== (<pivot> +- <tolerance>)
”
syntax of Matchers
.
- Value parameters:
- right
the
Spread[T]
against which to compare the left-hand value
- Returns:
a
TripleEqualsInvocationOnSpread
wrapping the passedSpread[T]
value, withexpectingEqual
set tofalse
.- Inherited from:
- TripleEqualsSupport
Returns a TripleEqualsInvocation[Null]
, given a null
reference, to facilitate
the “<left> should !== null
” syntax
of Matchers
.
Returns a TripleEqualsInvocation[Null]
, given a null
reference, to facilitate
the “<left> should !== null
” syntax
of Matchers
.
- Value parameters:
- right
a null reference
- Returns:
a
TripleEqualsInvocation
wrapping the passednull
value, withexpectingEqual
set tofalse
.- Inherited from:
- TripleEqualsSupport
Returns a TripleEqualsInvocation[T]
, given an object of type T
, to facilitate
the “<left> should !== <right>
” syntax
of Matchers
.
Returns a TripleEqualsInvocation[T]
, given an object of type T
, to facilitate
the “<left> should !== <right>
” syntax
of Matchers
.
- Value parameters:
- right
the right-hand side value for an equality assertion
- Returns:
a
TripleEqualsInvocation
wrapping the passed right value, withexpectingEqual
set tofalse
.- Inherited from:
- TripleEqualsSupport
Returns a TripleEqualsInvocationOnSpread[T]
, given an Spread[T]
, to facilitate
the “<left> should === (<pivot> +- <tolerance>)
”
syntax of Matchers
.
Returns a TripleEqualsInvocationOnSpread[T]
, given an Spread[T]
, to facilitate
the “<left> should === (<pivot> +- <tolerance>)
”
syntax of Matchers
.
- Value parameters:
- right
the
Spread[T]
against which to compare the left-hand value
- Returns:
a
TripleEqualsInvocationOnSpread
wrapping the passedSpread[T]
value, withexpectingEqual
set totrue
.- Inherited from:
- TripleEqualsSupport
Returns a TripleEqualsInvocation[Null]
, given a null
reference, to facilitate
the “<left> should === null
” syntax
of Matchers
.
Returns a TripleEqualsInvocation[Null]
, given a null
reference, to facilitate
the “<left> should === null
” syntax
of Matchers
.
- Value parameters:
- right
a null reference
- Returns:
a
TripleEqualsInvocation
wrapping the passednull
value, withexpectingEqual
set totrue
.- Inherited from:
- TripleEqualsSupport
Returns a TripleEqualsInvocation[T]
, given an object of type T
, to facilitate
the “<left> should === <right>
” syntax
of Matchers
.
Returns a TripleEqualsInvocation[T]
, given an object of type T
, to facilitate
the “<left> should === <right>
” syntax
of Matchers
.
- Value parameters:
- right
the right-hand side value for an equality assertion
- Returns:
a
TripleEqualsInvocation
wrapping the passed right value, withexpectingEqual
set totrue
.- Inherited from:
- TripleEqualsSupport
Returns an Alerter
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
AsyncFreeSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
print to the standard output. This method can be called safely by any thread.
Returns an Alerter
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
AsyncFreeSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
print to the standard output. This method can be called safely by any thread.
- Inherited from:
- AsyncFreeSpecLike
Assert that a boolean condition, described in String
message
, is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
with a helpful error message
appended with the String
obtained by invoking toString
on the
specified clue
as the exception's detail message.
Assert that a boolean condition, described in String
message
, is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
with a helpful error message
appended with the String
obtained by invoking toString
on the
specified clue
as the exception's detail message.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
-
assert(a == b, "a good clue")
-
assert(a != b, "a good clue")
-
assert(a === b, "a good clue")
-
assert(a !== b, "a good clue")
-
assert(a > b, "a good clue")
-
assert(a >= b, "a good clue")
-
assert(a < b, "a good clue")
-
assert(a <= b, "a good clue")
-
assert(a startsWith "prefix", "a good clue")
-
assert(a endsWith "postfix", "a good clue")
-
assert(a contains "something", "a good clue")
-
assert(a eq b, "a good clue")
-
assert(a ne b, "a good clue")
-
assert(a > 0 && b > 5, "a good clue")
-
assert(a > 0 || b > 5, "a good clue")
-
assert(a.isEmpty, "a good clue")
-
assert(!a.isEmpty, "a good clue")
-
assert(a.isInstanceOf[String], "a good clue")
-
assert(a.length == 8, "a good clue")
-
assert(a.size == 8, "a good clue")
-
assert(a.exists(_ == 8), "a good clue")
At this time, any other form of expression will just get a TestFailedException
with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the ===
that returns Boolean
to be the default in tests. This makes ===
consistent between tests and production
code.
- Value parameters:
- clue
An objects whose
toString
method returns a message to include in a failure report.- condition
the boolean condition to assert
- Throws:
- NullArgumentException
if
message
isnull
.- TestFailedException
if the condition is
false
.
- Inherited from:
- Assertions
Assert that a boolean condition is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
.
Assert that a boolean condition is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
-
assert(a == b)
-
assert(a != b)
-
assert(a === b)
-
assert(a !== b)
-
assert(a > b)
-
assert(a >= b)
-
assert(a < b)
-
assert(a <= b)
-
assert(a startsWith "prefix")
-
assert(a endsWith "postfix")
-
assert(a contains "something")
-
assert(a eq b)
-
assert(a ne b)
-
assert(a > 0 && b > 5)
-
assert(a > 0 || b > 5)
-
assert(a.isEmpty)
-
assert(!a.isEmpty)
-
assert(a.isInstanceOf[String])
-
assert(a.length == 8)
-
assert(a.size == 8)
-
assert(a.exists(_ == 8))
At this time, any other form of expression will get a TestFailedException
with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the ===
that returns Boolean
to be the default in tests. This makes ===
consistent between tests and production
code.
- Value parameters:
- condition
the boolean condition to assert
- Throws:
- TestFailedException
if the condition is
false
.
- Inherited from:
- Assertions
Asserts that a given string snippet of code passes both the Scala parser and type checker.
Asserts that a given string snippet of code passes both the Scala parser and type checker.
You can use this to make sure a snippet of code compiles:
assertCompiles("val a: Int = 1")
Although assertCompiles
is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string compiles, errors (i.e.,
snippets of code that do not compile) are reported as test failures at runtime.
- Value parameters:
- code
the snippet of code that should compile
- Inherited from:
- Assertions
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Often when creating libraries you may wish to ensure that certain arrangements of code that
represent potential “user errors” do not compile, so that your library is more error resistant.
ScalaTest's Assertions
trait includes the following syntax for that purpose:
assertDoesNotCompile("val a: String = \"a string")
Although assertDoesNotCompile
is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string doesn't compile, errors (i.e.,
snippets of code that do compile) are reported as test failures at runtime.
Note that the difference between assertTypeError
and assertDoesNotCompile
is
that assertDoesNotCompile
will succeed if the given code does not compile for any reason,
whereas assertTypeError
will only succeed if the given code does not compile because of
a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile
will return normally but assertTypeError
will throw a TestFailedException
.
- Value parameters:
- code
the snippet of code that should not type check
- Inherited from:
- Assertions
Assert that the value passed as expected
equals the value passed as actual
.
If the actual
value equals the expected
value
(as determined by ==
), assertResult
returns
normally. Else, assertResult
throws a
TestFailedException
whose detail message includes the expected and actual values.
Assert that the value passed as expected
equals the value passed as actual
.
If the actual
value equals the expected
value
(as determined by ==
), assertResult
returns
normally. Else, assertResult
throws a
TestFailedException
whose detail message includes the expected and actual values.
- Value parameters:
- actual
the actual value, which should equal the passed
expected
value- expected
the expected value
- Throws:
- TestFailedException
if the passed
actual
value does not equal the passedexpected
value.
- Inherited from:
- Assertions
Assert that the value passed as expected
equals the value passed as actual
.
If the actual
equals the expected
(as determined by ==
), assertResult
returns
normally. Else, if actual
is not equal to expected
, assertResult
throws a
TestFailedException
whose detail message includes the expected and actual values, as well as the String
obtained by invoking toString
on the passed clue
.
Assert that the value passed as expected
equals the value passed as actual
.
If the actual
equals the expected
(as determined by ==
), assertResult
returns
normally. Else, if actual
is not equal to expected
, assertResult
throws a
TestFailedException
whose detail message includes the expected and actual values, as well as the String
obtained by invoking toString
on the passed clue
.
- Value parameters:
- actual
the actual value, which should equal the passed
expected
value- clue
An object whose
toString
method returns a message to include in a failure report.- expected
the expected value
- Throws:
- TestFailedException
if the passed
actual
value does not equal the passedexpected
value.
- Inherited from:
- Assertions
Ensure that an expected exception is thrown by the passed function value. The thrown exception must be an instance of the
type specified by the type parameter of this method. This method invokes the passed
function. If the function throws an exception that's an instance of the specified type,
this method returns Succeeded
. Else, whether the passed function returns normally
or completes abruptly with a different exception, this method throws TestFailedException
.
Ensure that an expected exception is thrown by the passed function value. The thrown exception must be an instance of the
type specified by the type parameter of this method. This method invokes the passed
function. If the function throws an exception that's an instance of the specified type,
this method returns Succeeded
. Else, whether the passed function returns normally
or completes abruptly with a different exception, this method throws TestFailedException
.
Note that the type specified as this method's type parameter may represent any subtype of
AnyRef
, not just Throwable
or one of its subclasses. In
Scala, exceptions can be caught based on traits they implement, so it may at times make sense
to specify a trait that the intercepted exception's class must mix in. If a class instance is
passed for a type that could not possibly be used to catch an exception (such as String
,
for example), this method will complete abruptly with a TestFailedException
.
Also note that the difference between this method and intercept
is that this method
does not return the expected exception, so it does not let you perform further assertions on
that exception. Instead, this method returns Succeeded
, which means it can
serve as the last statement in an async- or safe-style suite. It also indicates to the reader
of the code that nothing further is expected about the thrown exception other than its type.
The recommended usage is to use assertThrows
by default, intercept
only when you
need to inspect the caught exception further.
- Value parameters:
- classTag
an implicit
ClassTag
representing the type of the specified type parameter.- f
the function value that should throw the expected exception
- Returns:
the
Succeeded
singleton, if an exception of the expected type is thrown- Throws:
- TestFailedException
if the passed function does not complete abruptly with an exception that's an instance of the specified type.
- Inherited from:
- Assertions
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Often when creating libraries you may wish to ensure that certain arrangements of code that
represent potential “user errors” do not compile, so that your library is more error resistant.
ScalaTest's Assertions
trait includes the following syntax for that purpose:
assertTypeError("val a: String = 1")
Although assertTypeError
is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string type checks, errors (i.e.,
snippets of code that do type check) are reported as test failures at runtime.
Note that the difference between assertTypeError
and assertDoesNotCompile
is
that assertDoesNotCompile
will succeed if the given code does not compile for any reason,
whereas assertTypeError
will only succeed if the given code does not compile because of
a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile
will return normally but assertTypeError
will throw a TestFailedException
.
- Value parameters:
- code
the snippet of code that should not type check
- Inherited from:
- Assertions
Assume that a boolean condition, described in String
message
, is true.
If the condition is true
, this method returns normally.
Else, it throws TestCanceledException
with a helpful error message
appended with String
obtained by invoking toString
on the
specified clue
as the exception's detail message.
Assume that a boolean condition, described in String
message
, is true.
If the condition is true
, this method returns normally.
Else, it throws TestCanceledException
with a helpful error message
appended with String
obtained by invoking toString
on the
specified clue
as the exception's detail message.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
-
assume(a == b, "a good clue")
-
assume(a != b, "a good clue")
-
assume(a === b, "a good clue")
-
assume(a !== b, "a good clue")
-
assume(a > b, "a good clue")
-
assume(a >= b, "a good clue")
-
assume(a < b, "a good clue")
-
assume(a <= b, "a good clue")
-
assume(a startsWith "prefix", "a good clue")
-
assume(a endsWith "postfix", "a good clue")
-
assume(a contains "something", "a good clue")
-
assume(a eq b, "a good clue")
-
assume(a ne b, "a good clue")
-
assume(a > 0 && b > 5, "a good clue")
-
assume(a > 0 || b > 5, "a good clue")
-
assume(a.isEmpty, "a good clue")
-
assume(!a.isEmpty, "a good clue")
-
assume(a.isInstanceOf[String], "a good clue")
-
assume(a.length == 8, "a good clue")
-
assume(a.size == 8, "a good clue")
-
assume(a.exists(_ == 8), "a good clue")
At this time, any other form of expression will just get a TestCanceledException
with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the ===
that returns Boolean
to be the default in tests. This makes ===
consistent between tests and production
code.
- Value parameters:
- clue
An objects whose
toString
method returns a message to include in a failure report.- condition
the boolean condition to assume
- Throws:
- NullArgumentException
if
message
isnull
.- TestCanceledException
if the condition is
false
.
- Inherited from:
- Assertions
Assume that a boolean condition is true.
If the condition is true
, this method returns normally.
Else, it throws TestCanceledException
.
Assume that a boolean condition is true.
If the condition is true
, this method returns normally.
Else, it throws TestCanceledException
.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
-
assume(a == b)
-
assume(a != b)
-
assume(a === b)
-
assume(a !== b)
-
assume(a > b)
-
assume(a >= b)
-
assume(a < b)
-
assume(a <= b)
-
assume(a startsWith "prefix")
-
assume(a endsWith "postfix")
-
assume(a contains "something")
-
assume(a eq b)
-
assume(a ne b)
-
assume(a > 0 && b > 5)
-
assume(a > 0 || b > 5)
-
assume(a.isEmpty)
-
assume(!a.isEmpty)
-
assume(a.isInstanceOf[String])
-
assume(a.length == 8)
-
assume(a.size == 8)
-
assume(a.exists(_ == 8))
At this time, any other form of expression will just get a TestCanceledException
with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the ===
that returns Boolean
to be the default in tests. This makes ===
consistent between tests and production
code.
- Value parameters:
- condition
the boolean condition to assume
- Throws:
- TestCanceledException
if the condition is
false
.
- Inherited from:
- Assertions
Throws TestCanceledException
, with the passed
Throwable
cause, to indicate a test failed.
The getMessage
method of the thrown TestCanceledException
will return cause.toString
.
Throws TestCanceledException
, with the passed
Throwable
cause, to indicate a test failed.
The getMessage
method of the thrown TestCanceledException
will return cause.toString
.
- Value parameters:
- cause
a
Throwable
that indicates the cause of the cancellation.
- Throws:
- NullArgumentException
if
cause
isnull
- Inherited from:
- Assertions
Throws TestCanceledException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed.
Throws TestCanceledException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed.
- Value parameters:
- cause
A
Throwable
that indicates the cause of the failure.- message
A message describing the failure.
- Throws:
- NullArgumentException
if
message
orcause
isnull
- Inherited from:
- Assertions
Throws TestCanceledException
, with the passed
String
message
as the exception's detail
message, to indicate a test was canceled.
Throws TestCanceledException
, with the passed
String
message
as the exception's detail
message, to indicate a test was canceled.
- Value parameters:
- message
A message describing the cancellation.
- Throws:
- NullArgumentException
if
message
isnull
- Inherited from:
- Assertions
Throws TestCanceledException
to indicate a test was canceled.
Throws TestCanceledException
to indicate a test was canceled.
- Inherited from:
- Assertions
Registers a block of code that produces any "futuristic" type (any type F
for which
an implicit Futuristic[F]
instance is implicitly available), returning
an object that offers a lastly
method.
Registers a block of code that produces any "futuristic" type (any type F
for which
an implicit Futuristic[F]
instance is implicitly available), returning
an object that offers a lastly
method.
See the main documentation for trait CompleteLastly
for more detail.
- Value parameters:
- completeBlock
cleanup code to execute whether the code passed to
complete
throws an exception or succesfully returns a futuristic value.
- Inherited from:
- CompleteLastly
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
Returns an Equality[A]
for any type A
that determines equality
by first calling .deep
on any Array
(on either the left or right side),
then comparing the resulting objects with ==
.
Returns an Equality[A]
for any type A
that determines equality
by first calling .deep
on any Array
(on either the left or right side),
then comparing the resulting objects with ==
.
- Returns:
a default
Equality
for typeA
- Inherited from:
- TripleEqualsSupport
Executes one or more tests in this Suite
, printing results to the standard output.
Executes one or more tests in this Suite
, printing results to the standard output.
This method invokes run
on itself, passing in values that can be configured via the parameters to this
method, all of which have default values. This behavior is convenient when working with ScalaTest in the Scala interpreter.
Here's a summary of this method's parameters and how you can use them:
The testName
parameter
If you leave testName
at its default value (of null
), this method will pass None
to
the testName
parameter of run
, and as a result all the tests in this suite will be executed. If you
specify a testName
, this method will pass Some(testName)
to run
, and only that test
will be run. Thus to run all tests in a suite from the Scala interpreter, you can write:
scala> (new ExampleSuite).execute()
(The above syntax actually invokes the overloaded parameterless form of execute
, which calls this form with its default parameter values.)
To run just the test named "my favorite test"
in a suite from the Scala interpreter, you would write:
scala> (new ExampleSuite).execute("my favorite test")
Or:
scala> (new ExampleSuite).execute(testName = "my favorite test")
The configMap
parameter
If you provide a value for the configMap
parameter, this method will pass it to run
. If not, the default value
of an empty Map
will be passed. For more information on how to use a config map to configure your test suites, see
the config map section in the main documentation for this trait. Here's an example in which you configure
a run with the name of an input file:
scala> (new ExampleSuite).execute(configMap = Map("inputFileName" -> "in.txt")
The color
parameter
If you leave the color
parameter unspecified, this method will configure the reporter it passes to run
to print
to the standard output in color (via ansi escape characters). If you don't want color output, specify false for color
, like this:
scala> (new ExampleSuite).execute(color = false)
The durations
parameter
If you leave the durations
parameter unspecified, this method will configure the reporter it passes to run
to
not print durations for tests and suites to the standard output. If you want durations printed, specify true for durations
,
like this:
scala> (new ExampleSuite).execute(durations = true)
The shortstacks
and fullstacks
parameters
If you leave both the shortstacks
and fullstacks
parameters unspecified, this method will configure the reporter
it passes to run
to not print stack traces for failed tests if it has a stack depth that identifies the offending
line of test code. If you prefer a short stack trace (10 to 15 stack frames) to be printed with any test failure, specify true for
shortstacks
:
scala> (new ExampleSuite).execute(shortstacks = true)
For full stack traces, set fullstacks
to true:
scala> (new ExampleSuite).execute(fullstacks = true)
If you specify true for both shortstacks
and fullstacks
, you'll get full stack traces.
The stats
parameter
If you leave the stats
parameter unspecified, this method will not fire RunStarting
and either RunCompleted
or RunAborted
events to the reporter it passes to run
.
If you specify true for stats
, this method will fire the run events to the reporter, and the reporter will print the
expected test count before the run, and various statistics after, including the number of suites completed and number of tests that
succeeded, failed, were ignored or marked pending. Here's how you get the stats:
scala> (new ExampleSuite).execute(stats = true)
To summarize, this method will pass to run
:
-
testName
-None
if this method'stestName
parameter is left at its default value ofnull
, elseSome(testName)
. -
reporter
- a reporter that prints to the standard output -
stopper
- aStopper
whoseapply
method always returnsfalse
-
filter
- aFilter
constructed withNone
fortagsToInclude
andSet()
fortagsToExclude
-
configMap
- theconfigMap
passed to this method -
distributor
-None
-
tracker
- a newTracker
Note: In ScalaTest, the terms "execute" and "run" basically mean the same thing and
can be used interchangably. The reason this method isn't named run
is that it takes advantage of
default arguments, and you can't mix overloaded methods and default arguments in Scala. (If named run
,
this method would have the same name but different arguments than the main run
method that
takes seven arguments. Thus it would overload and couldn't be used with default argument values.)
Design note: This method has two "features" that may seem unidiomatic. First, the default value of testName
is null
.
Normally in Scala the type of testName
would be Option[String]
and the default value would
be None
, as it is in this trait's run
method. The null
value is used here for two reasons. First, in
ScalaTest 1.5, execute
was changed from four overloaded methods to one method with default values, taking advantage of
the default and named parameters feature introduced in Scala 2.8.
To not break existing source code, testName
needed to have type String
, as it did in two of the overloaded
execute
methods prior to 1.5. The other reason is that execute
has always been designed to be called primarily
from an interpeter environment, such as the Scala REPL (Read-Evaluate-Print-Loop). In an interpreter environment, minimizing keystrokes is king.
A String
type with a null
default value lets users type suite.execute("my test name")
rather than
suite.execute(Some("my test name"))
, saving several keystrokes.
The second non-idiomatic feature is that shortstacks
and fullstacks
are all lower case rather than
camel case. This is done to be consistent with the Shell
, which also uses those forms. The reason
lower case is used in the Shell
is to save keystrokes in an interpreter environment. Most Unix commands, for
example, are all lower case, making them easier and quicker to type. In the ScalaTest
Shell
, methods like shortstacks
, fullstacks
, and nostats
, etc., are
designed to be all lower case so they feel more like shell commands than methods.
- Value parameters:
- color
a boolean that configures whether output is printed in color
- configMap
a
Map
of key-value pairs that can be used by the executingSuite
of tests.- durations
a boolean that configures whether test and suite durations are printed to the standard output
- fullstacks
a boolean that configures whether full stack traces should be printed for test failures
- shortstacks
a boolean that configures whether short stack traces should be printed for test failures
- stats
a boolean that configures whether test and suite statistics are printed to the standard output
- testName
the name of one test to run.
- Throws:
- IllegalArgumentException
if
testName
is defined, but no test with the specified test name exists in thisSuite
- NullArgumentException
if the passed
configMap
parameter isnull
.
- Inherited from:
- Suite
The total number of tests that are expected to run when this Suite
's run
method is invoked.
The total number of tests that are expected to run when this Suite
's run
method is invoked.
This trait's implementation of this method returns the sum of:
-
the size of the
testNames
List
, minus the number of tests marked as ignored and any tests that are exluded by the passedFilter
-
the sum of the values obtained by invoking
expectedTestCount
on every nestedSuite
contained innestedSuites
- Value parameters:
- filter
a
Filter
with which to filter tests to count based on their tags
- Inherited from:
- Suite
Throws TestFailedException
, with the passed
Throwable
cause, to indicate a test failed.
The getMessage
method of the thrown TestFailedException
will return cause.toString
.
Throws TestFailedException
, with the passed
Throwable
cause, to indicate a test failed.
The getMessage
method of the thrown TestFailedException
will return cause.toString
.
- Value parameters:
- cause
a
Throwable
that indicates the cause of the failure.
- Throws:
- NullArgumentException
if
cause
isnull
- Inherited from:
- Assertions
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed.
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed.
- Value parameters:
- cause
A
Throwable
that indicates the cause of the failure.- message
A message describing the failure.
- Throws:
- NullArgumentException
if
message
orcause
isnull
- Inherited from:
- Assertions
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message, to indicate a test failed.
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message, to indicate a test failed.
- Value parameters:
- message
A message describing the failure.
- Throws:
- NullArgumentException
if
message
isnull
- Inherited from:
- Assertions
Throws TestFailedException
to indicate a test failed.
Throws TestFailedException
to indicate a test failed.
- Inherited from:
- Assertions
Returns an Informer
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded
. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
Returns an Informer
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded
. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
- Inherited from:
- AsyncFreeSpecLike
Intercept and return an exception that's expected to
be thrown by the passed function value. The thrown exception must be an instance of the
type specified by the type parameter of this method. This method invokes the passed
function. If the function throws an exception that's an instance of the specified type,
this method returns that exception. Else, whether the passed function returns normally
or completes abruptly with a different exception, this method throws TestFailedException
.
Intercept and return an exception that's expected to
be thrown by the passed function value. The thrown exception must be an instance of the
type specified by the type parameter of this method. This method invokes the passed
function. If the function throws an exception that's an instance of the specified type,
this method returns that exception. Else, whether the passed function returns normally
or completes abruptly with a different exception, this method throws TestFailedException
.
Note that the type specified as this method's type parameter may represent any subtype of
AnyRef
, not just Throwable
or one of its subclasses. In
Scala, exceptions can be caught based on traits they implement, so it may at times make sense
to specify a trait that the intercepted exception's class must mix in. If a class instance is
passed for a type that could not possibly be used to catch an exception (such as String
,
for example), this method will complete abruptly with a TestFailedException
.
Also note that the difference between this method and assertThrows
is that this method
returns the expected exception, so it lets you perform further assertions on
that exception. By contrast, the assertThrows
method returns Succeeded
, which means it can
serve as the last statement in an async- or safe-style suite. assertThrows
also indicates to the reader
of the code that nothing further is expected about the thrown exception other than its type.
The recommended usage is to use assertThrows
by default, intercept
only when you
need to inspect the caught exception further.
- Value parameters:
- classTag
an implicit
ClassTag
representing the type of the specified type parameter.- f
the function value that should throw the expected exception
- Returns:
the intercepted exception, if it is of the expected type
- Throws:
- TestFailedException
if the passed function does not complete abruptly with an exception that's an instance of the specified type.
- Inherited from:
- Assertions
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
Returns a Documenter
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded
. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
Returns a Documenter
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded
. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
- Inherited from:
- AsyncFreeSpecLike
An immutable IndexedSeq
of this Suite
object's nested Suite
s. If this Suite
contains no nested Suite
s,
this method returns an empty IndexedSeq
. This trait's implementation of this method returns an empty List
.
An immutable IndexedSeq
of this Suite
object's nested Suite
s. If this Suite
contains no nested Suite
s,
this method returns an empty IndexedSeq
. This trait's implementation of this method returns an empty List
.
- Inherited from:
- Suite
Returns a Notifier
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
AsyncFreeSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
print to the standard output. This method can be called safely by any thread.
Returns a Notifier
that during test execution will forward strings passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
AsyncFreeSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
print to the standard output. This method can be called safely by any thread.
- Inherited from:
- AsyncFreeSpecLike
Throws TestPendingException
to indicate a test is pending.
Throws TestPendingException
to indicate a test is pending.
A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.
To support this style of testing, a test can be given a name that specifies one
bit of behavior required by the system being tested. The test can also include some code that
sends more information about the behavior to the reporter when the tests run. At the end of the test,
it can call method pending
, which will cause it to complete abruptly with TestPendingException
.
Because tests in ScalaTest can be designated as pending with TestPendingException
, both the test name and any information
sent to the reporter when running the test can appear in the report of a test run. (In other words,
the code of a pending test is executed just like any other test.) However, because the test completes abruptly
with TestPendingException
, the test will be reported as pending, to indicate
the actual test, and possibly the functionality it is intended to test, has not yet been implemented.
Note: This method always completes abruptly with a TestPendingException
. Thus it always has a side
effect. Methods with side effects are usually invoked with parentheses, as in pending()
. This
method is defined as a parameterless method, in flagrant contradiction to recommended Scala style, because it
forms a kind of DSL for pending tests. It enables tests in suites such as FunSuite
or FunSpec
to be denoted by placing "(pending)
" after the test name, as in:
test("that style rules are not laws") (pending)
Readers of the code see "pending" in parentheses, which looks like a little note attached to the test name to indicate
it is pending. Whereas "(pending())
looks more like a method call, "(pending)
" lets readers
stay at a higher level, forgetting how it is implemented and just focusing on the intent of the programmer who wrote the code.
- Inherited from:
- Assertions
Execute the passed block of code, and if it completes abruptly, throw TestPendingException
, else
throw TestFailedException
.
Execute the passed block of code, and if it completes abruptly, throw TestPendingException
, else
throw TestFailedException
.
This method can be used to temporarily change a failing test into a pending test in such a way that it will
automatically turn back into a failing test once the problem originally causing the test to fail has been fixed.
At that point, you need only remove the pendingUntilFixed
call. In other words, a
pendingUntilFixed
surrounding a block of code that isn't broken is treated as a test failure.
The motivation for this behavior is to encourage people to remove pendingUntilFixed
calls when
there are no longer needed.
This method facilitates a style of testing in which tests are written before the code they test. Sometimes you may
encounter a test failure that requires more functionality than you want to tackle without writing more tests. In this
case you can mark the bit of test code causing the failure with pendingUntilFixed
. You can then write more
tests and functionality that eventually will get your production code to a point where the original test won't fail anymore.
At this point the code block marked with pendingUntilFixed
will no longer throw an exception (because the
problem has been fixed). This will in turn cause pendingUntilFixed
to throw TestFailedException
with a detail message explaining you need to go back and remove the pendingUntilFixed
call as the problem orginally
causing your test code to fail has been fixed.
- Value parameters:
- f
a block of code, which if it completes abruptly, should trigger a
TestPendingException
- Throws:
- TestPendingException
if the passed block of code completes abruptly with an
Exception
orAssertionError
- Inherited from:
- Assertions
Transforms a future of any type into a Future[T]
, where T
is a given
expected exception type, which succeeds if the given future
completes with a Failure
containing the specified exception type.
Transforms a future of any type into a Future[T]
, where T
is a given
expected exception type, which succeeds if the given future
completes with a Failure
containing the specified exception type.
See the main documentation for this trait for more detail and examples.
- Value parameters:
- future
A future of any type, which you expect to fail with an exception of the specified type T
- Returns:
a Future[T] containing on success the expected exception, or containing on failure a
TestFailedException
- Inherited from:
- RecoverMethods
Transforms a future of any type into a Future[Assertion]
that succeeds if the future
completes with a Failure
containing the specified exception type.
Transforms a future of any type into a Future[Assertion]
that succeeds if the future
completes with a Failure
containing the specified exception type.
See the main documentation for this trait for more detail and examples.
- Value parameters:
- future
A future of any type, which you expect to fail with an exception of the specified type T
- Returns:
a Future[Assertion] containing on success the
Succeeded
singleton, or containing on failure aTestFailedException
- Inherited from:
- RecoverMethods
- Inherited from:
- AsyncFreeSpecLike
- Inherited from:
- AsyncFreeSpecLike
The fully qualified class name of the rerunner to rerun this suite. This implementation will look at this.getClass and see if it is either an accessible Suite, or it has a WrapWith annotation. If so, it returns the fully qualified class name wrapped in a Some, or else it returns None.
The fully qualified class name of the rerunner to rerun this suite. This implementation will look at this.getClass and see if it is either an accessible Suite, or it has a WrapWith annotation. If so, it returns the fully qualified class name wrapped in a Some, or else it returns None.
- Inherited from:
- Suite
Run a test. This trait's implementation runs the test registered with the name specified by
testName
. Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documentation
for testNames
for an example.)
Run a test. This trait's implementation runs the test registered with the name specified by
testName
. Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documentation
for testNames
for an example.)
- Value parameters:
- args
the
Args
for this run- testName
the name of one test to execute.
- Returns:
a
Status
object that indicates when the test started by this method has completed, and whether or not it failed .- Throws:
- NullArgumentException
if any of
testName
,reporter
,stopper
, orconfigMap
isnull
.
- Definition Classes
- Inherited from:
- AsyncFreeSpecLike
Run zero to many of this AsyncFreeSpec
's tests.
Run zero to many of this AsyncFreeSpec
's tests.
This method takes a testName
parameter that optionally specifies a test to invoke.
If testName
is Some
, this trait's implementation of this method
invokes runTest
on this object, passing in:
-
testName
- theString
value of thetestName
Option
passed to this method -
reporter
- theReporter
passed to this method, or one that wraps and delegates to it -
stopper
- theStopper
passed to this method, or one that wraps and delegates to it -
configMap
- theconfigMap
passed to this method, or one that wraps and delegates to it
This method takes a Set
of tag names that should be included (tagsToInclude
), and a Set
that should be excluded (tagsToExclude
), when deciding which of this Suite
's tests to execute.
If tagsToInclude
is empty, all tests will be executed
except those those belonging to tags listed in the tagsToExclude
Set
. If tagsToInclude
is non-empty, only tests
belonging to tags mentioned in tagsToInclude
, and not mentioned in tagsToExclude
will be executed. However, if testName
is Some
, tagsToInclude
and tagsToExclude
are essentially ignored.
Only if testName
is None
will tagsToInclude
and tagsToExclude
be consulted to
determine which of the tests named in the testNames
Set
should be run. For more information on trait tags, see the main documentation for this trait.
If testName
is None
, this trait's implementation of this method
invokes testNames
on this Suite
to get a Set
of names of tests to potentially execute.
(A testNames
value of None
essentially acts as a wildcard that means all tests in
this Suite
that are selected by tagsToInclude
and tagsToExclude
should be executed.)
For each test in the testName
Set
, in the order
they appear in the iterator obtained by invoking the elements
method on the Set
, this trait's implementation
of this method checks whether the test should be run based on the tagsToInclude
and tagsToExclude
Set
s.
If so, this implementation invokes runTest
, passing in:
-
testName
- theString
name of the test to run (which will be one of the names in thetestNames
Set
) -
reporter
- theReporter
passed to this method, or one that wraps and delegates to it -
stopper
- theStopper
passed to this method, or one that wraps and delegates to it -
configMap
- theconfigMap
passed to this method, or one that wraps and delegates to it
- Value parameters:
- args
the
Args
for this run- testName
an optional name of one test to run. If
None
, all relevant tests should be run. I.e.,None
acts like a wildcard that means run all relevant tests in thisSuite
.
- Returns:
a
Status
object that indicates when all tests started by this method have completed, and whether or not a failure occurred.- Throws:
- IllegalArgumentException
if
testName
is defined, but no test with the specified test name exists in thisSuite
- NullArgumentException
if any of the passed parameters is
null
.
- Definition Classes
- AsyncFreeSpecLike -> Suite
- Inherited from:
- AsyncFreeSpecLike
A string ID for this Suite
that is intended to be unique among all suites reported during a run.
A string ID for this Suite
that is intended to be unique among all suites reported during a run.
This trait's
implementation of this method returns the fully qualified name of this object's class.
Each suite reported during a run will commonly be an instance of a different Suite
class,
and in such cases, this default implementation of this method will suffice. However, in special cases
you may need to override this method to ensure it is unique for each reported suite. For example, if you write
a Suite
subclass that reads in a file whose name is passed to its constructor and dynamically
creates a suite of tests based on the information in that file, you will likely need to override this method
in your Suite
subclass, perhaps by appending the pathname of the file to the fully qualified class name.
That way if you run a suite of tests based on a directory full of these files, you'll have unique suite IDs for
each reported suite.
The suite ID is intended to be unique, because ScalaTest does not enforce that it is unique. If it is not unique, then you may not be able to uniquely identify a particular test of a particular suite. This ability is used, for example, to dynamically tag tests as having failed in the previous run when rerunning only failed tests.
- Returns:
this
Suite
object's ID.- Inherited from:
- Suite
A user-friendly suite name for this Suite
.
A user-friendly suite name for this Suite
.
This trait's
implementation of this method returns the simple name of this object's class. This
trait's implementation of runNestedSuites
calls this method to obtain a
name for Report
s to pass to the suiteStarting
, suiteCompleted
,
and suiteAborted
methods of the Reporter
.
- Returns:
this
Suite
object's suite name.- Inherited from:
- Suite
A Map
whose keys are String
names of tagged tests and whose associated values are
the Set
of tags for the test. If this AsyncFreeSpec
contains no tags, this method returns an empty Map
.
A Map
whose keys are String
names of tagged tests and whose associated values are
the Set
of tags for the test. If this AsyncFreeSpec
contains no tags, this method returns an empty Map
.
This trait's implementation returns tags that were passed as strings contained in Tag
objects passed to
taggedAs
.
In addition, this trait's implementation will also auto-tag tests with class level annotations.
For example, if you annotate @Ignore
at the class level, all test methods in the class will be auto-annotated with
org.scalatest.Ignore
.
- Definition Classes
- AsyncFreeSpecLike -> Suite
- Inherited from:
- AsyncFreeSpecLike
An immutable Set
of test names. If this AsyncFreeSpec
contains no tests, this method returns an
empty Set
.
An immutable Set
of test names. If this AsyncFreeSpec
contains no tests, this method returns an
empty Set
.
This trait's implementation of this method will return a set that contains the names of all registered tests. The set's
iterator will return those names in the order in which the tests were registered. Each test's name is composed
of the concatenation of the text of each surrounding describer, in order from outside in, and the text of the
example itself, with all components separated by a space. For example, consider this AsyncFreeSpec
:
import org.scalatest.freespec.AsyncFreeSpec class StackSpec extends AsyncFreeSpec { "A Stack" - { "when not empty" - { "must allow me to pop" in {} } "when not full" - { "must allow me to push" in {} } } }
Invoking testNames
on this AsyncFreeSpec
will yield a set that contains the following
two test name strings:
"A Stack when not empty must allow me to pop" "A Stack when not full must allow me to push"
- Definition Classes
- AsyncFreeSpecLike -> Suite
- Inherited from:
- AsyncFreeSpecLike
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
Executes the block of code passed as the second parameter, and, if it
completes abruptly with a ModifiableMessage
exception,
prepends the "clue" string passed as the first parameter to the beginning of the detail message
of that thrown exception, then rethrows it. If clue does not end in a white space
character, one space will be added
between it and the existing detail message (unless the detail message is
not defined).
Executes the block of code passed as the second parameter, and, if it
completes abruptly with a ModifiableMessage
exception,
prepends the "clue" string passed as the first parameter to the beginning of the detail message
of that thrown exception, then rethrows it. If clue does not end in a white space
character, one space will be added
between it and the existing detail message (unless the detail message is
not defined).
This method allows you to add more information about what went wrong that will be reported when a test fails. Here's an example:
withClue("(Employee's name was: " + employee.name + ")") { intercept[IllegalArgumentException] { employee.getTask(-1) } }
If an invocation of intercept
completed abruptly with an exception, the resulting message would be something like:
(Employee's name was Bob Jones) Expected IllegalArgumentException to be thrown, but no exception was thrown
- Throws:
- NullArgumentException
if the passed
clue
isnull
- Inherited from:
- Assertions
Run the passed test function in the context of a fixture established by this method.
Run the passed test function in the context of a fixture established by this method.
This method should set up the fixture needed by the tests of the
current suite, invoke the test function, and if needed, register a callback
on the resulting FutureOutcome
to perform any clean
up needed after the test completes. Because the NoArgAsyncTest
function
passed to this method takes no parameters, preparing the fixture will require
side effects, such as reassigning instance var
s in this Suite
or initializing
a globally accessible external database. If you want to avoid reassigning instance var
s
you can use FixtureAsyncTestSuite.
This trait's implementation of runTest
invokes this method for each test, passing
in a NoArgAsyncTest
whose apply
method will execute the code of the test
and returns its result.
This trait's implementation of this method simply invokes the passed NoArgAsyncTest
function.
- Value parameters:
- test
the no-arg async test function to run with a fixture
- Inherited from:
- AsyncTestSuite
Deprecated and Inherited methods
- Deprecated
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
- Deprecated
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
- Deprecated
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
- Deprecated
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals
Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException
indicating no exception is thrown.
Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException
indicating no exception is thrown.
This method is intended to be used in the Scala interpreter to eliminate large stack traces when trying out ScalaTest assertions and
matcher expressions. It is not intended to be used in regular test code. If you want to ensure that a bit of code throws an expected
exception, use intercept
, not trap
. Here's an example interpreter session without trap
:
scala> import org.scalatest._ import org.scalatest._ scala> import Matchers._ import Matchers._ scala> val x = 12 a: Int = 12 scala> x shouldEqual 13 org.scalatest.exceptions.TestFailedException: 12 did not equal 13 at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:449) at org.scalatest.Assertions$.newAssertionFailedException(Assertions.scala:1203) at org.scalatest.Assertions$AssertionsHelper.macroAssertTrue(Assertions.scala:417) at .<init>(<console>:15) at .<clinit>(<console>) at .<init>(<console>:7) at .<clinit>(<console>) at $print(<console>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:731) at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:980) at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:570) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:601) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565) at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745) at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790) at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702) at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566) at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573) at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135) at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822) at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83) at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96) at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105) at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
That's a pretty tall stack trace. Here's what it looks like when you use trap
:
scala> trap { x shouldEqual 13 } res1: Throwable = org.scalatest.exceptions.TestFailedException: 12 did not equal 13
Much less clutter. Bear in mind, however, that if no exception is thrown by the
passed block of code, the trap
method will create a new NormalResult
(a subclass of Throwable
made for this purpose only) and return that. If the result was the Unit
value, it
will simply say that no exception was thrown:
scala> trap { x shouldEqual 12 } res2: Throwable = No exception was thrown.
If the passed block of code results in a value other than Unit
, the NormalResult
's toString
will print the value:
scala> trap { "Dude!" } res3: Throwable = No exception was thrown. Instead, result was: "Dude!"
Although you can access the result value from the NormalResult
, its type is Any
and therefore not
very convenient to use. It is not intended that trap
be used in test code. The sole intended use case for trap
is decluttering
Scala interpreter sessions by eliminating stack traces when executing assertion and matcher expressions.
- Deprecated
- Inherited from:
- Assertions
Inherited fields
Supports shared test registration in AsyncFreeSpec
s.
Supports shared test registration in AsyncFreeSpec
s.
This field enables syntax such as the following:
behave like nonFullStack(stackWithOneItem) ^
For more information and examples of the use of
- Inherited from:
- AsyncFreeSpecLike
The Succeeded
singleton.
The Succeeded
singleton.
You can use succeed
to solve a type error when an async test
does not end in either Future[Assertion]
or Assertion
.
Because Assertion
is a type alias for Succeeded.type
,
putting succeed
at the end of a test body (or at the end of a
function being used to map the final future of a test body) will solve
the type error.
- Inherited from:
- Assertions
Deprecated and Inherited fields
The styleName
lifecycle method has been deprecated and will be removed in a future version of ScalaTest.
The styleName
lifecycle method has been deprecated and will be removed in a future version of ScalaTest.
This method was used to support the chosen styles feature, which was deactivated in 3.1.0. The internal modularization of ScalaTest in 3.2.0
will replace chosen styles as the tool to encourage consistency across a project. We do not plan a replacement for styleName
.
- Deprecated
- Inherited from:
- AsyncFreeSpecLike
Extensions
Inherited extensions
Implicits
Inherited implicits
Implicitly converts an Assertion
to a Future[Assertion]
.
Implicitly converts an Assertion
to a Future[Assertion]
.
This implicit conversion is used to allow synchronous tests to be included along with
asynchronous tests in an AsyncTestSuite
. It will be
- Value parameters:
- assertion
the
Assertion
to convert
- Returns:
a
Future[Assertion]
that has already completed successfully (containing theSucceeded
singleton).- Inherited from:
- AsyncTestSuite
- Inherited from:
- AsyncTestSuite
Implicitly converts String
s to FreeSpecStringWrapper
, which enables
methods in
, is
, taggedAs
and ignore
,
as well as the dash operator (-
), to be invoked on String
s.
Implicitly converts String
s to FreeSpecStringWrapper
, which enables
methods in
, is
, taggedAs
and ignore
,
as well as the dash operator (-
), to be invoked on String
s.
- Inherited from:
- AsyncFreeSpecLike
- Definition Classes
- TripleEquals -> TripleEqualsSupport
- Inherited from:
- TripleEquals