A suite of property-based tests.
A suite of property-based tests.
Recommended Usage:
Class AnyPropSpec is a good fit for teams that want to write tests exclusively in terms of property checks, and is also a good choice
for writing the occasional test matrix when a different style trait is chosen as the main unit testing style.
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Here's an example AnyPropSpec
:
package org.scalatest.examples.propspec import org.scalatest._ import prop._ import scala.collection.immutable._ class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with Matchers { val examples = Table( "set", BitSet.empty, HashSet.empty[Int], TreeSet.empty[Int] ) property("an empty Set should have size 0") { forAll(examples) { set => set.size should be (0) } } property("invoking head on an empty set should produce NoSuchElementException") { forAll(examples) { set => a [NoSuchElementException] should be thrownBy { set.head } } } }
You can run a AnyPropSpec
by invoking execute
on it.
This method, which prints test results to the standard output, is intended to serve as a
convenient way to run tests from within the Scala interpreter. For example,
to run SetSpec
from within the Scala interpreter, you could write:
scala> org.scalatest.run(new SetSpec)
And you would see:
SetSpec:
- an empty Set should have size 0
- invoking head on an empty Set should produce NoSuchElementException
Or, to run just the “an empty Set should have size 0
” method, you could pass that test's name, or any unique substring of the
name, such as "size 0"
or even just "0"
. Here's an example:
scala> org.scalatest.run(new SetSpec, "size 0")
SetSpec:
- an empty Set should have size 0
You can also pass to execute
a config map of key-value
pairs, which will be passed down into suites and tests, as well as other parameters that configure the run itself.
For more information on running in the Scala interpreter, see the documentation for execute
(below) and the
ScalaTest shell.
The execute
method invokes a run
method that takes two
parameters. This run
method, which actually executes the suite, will usually be invoked by a test runner, such
as run
, tools.Runner
, a build tool, or an IDE.
“property
” is a method, defined in AnyPropSpec
, which will be invoked
by the primary constructor of SetSpec
. You specify the name of the test as
a string between the parentheses, and the test code itself between curly braces.
The test code is a function passed as a by-name parameter to property
, which registers
it for later execution.
A AnyPropSpec
'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 property
method while the AnyPropSpec
is
in its registration phase. Any attempt to register a test after the AnyPropSpec
has
entered its ready phase, i.e., after run
has been invoked on the AnyPropSpec
,
will be met with a thrown TestRegistrationClosedException
. The recommended style
of using AnyPropSpec
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
.
To support the common use case of temporarily disabling a test, with the
good intention of resurrecting the test at a later time, AnyPropSpec
provides registration
methods that start with ignore
instead of property
. Here's an example:
package org.scalatest.examples.suite.ignore import org.scalatest._ import prop._ import scala.collection.immutable._ class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with Matchers { val examples = Table( "set", BitSet.empty, HashSet.empty[Int], TreeSet.empty[Int] ) ignore("an empty Set should have size 0") { forAll(examples) { set => set.size should be (0) } } property("invoking head on an empty set should produce NoSuchElementException") { forAll(examples) { set => a [NoSuchElementException] should be thrownBy { set.head } } } }
If you run this version of SetSuite
with:
scala> org.scalatest.run(new SetSpec)
It will run only the second test and report that the first test was ignored:
SetSuite: - an empty Set should have size 0 !!! IGNORED !!! - invoking head on an empty Set should produce NoSuchElementException
One of the parameters to AnyPropSpec
'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 AnyPropSpec
'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.
Here's an example that shows both a direct use as well as an indirect use through the methods
of GivenWhenThen
:
package org.scalatest.examples.propspec.info import org.scalatest._ import prop._ import collection.mutable class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with GivenWhenThen { val examples = Table( "set", mutable.BitSet.empty, mutable.HashSet.empty[Int], mutable.LinkedHashSet.empty[Int] ) property("an element can be added to an empty mutable Set") { forAll(examples) { set => info("----------------") Given("an empty mutable " + set.getClass.getSimpleName) assert(set.isEmpty) When("an element is added") set += 99 Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains(99)) } } }
If you run this AnyPropSpec
from the interpreter, you will see the following output:
scala> org.scalatest.run(new SetSpec)
SetSpec:
- an element can be added to an empty mutable Set
+ ----------------
+ Given an empty mutable BitSet
+ When an element is added
+ Then the Set should have size 1
+ And the Set should contain the added element
+ ----------------
+ Given an empty mutable HashSet
+ When an element is added
+ Then the Set should have size 1
+ And the Set should contain the added element
+ ----------------
+ Given an empty mutable LinkedHashSet
+ When an element is added
+ Then the Set should have size 1
+ And the Set should contain the added element
AnyPropSpec
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 AnyPropSpec
that uses markup
:
package org.scalatest.examples.propspec.markup import org.scalatest._ import prop._ import collection.mutable class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks 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. """ } val examples = Table( "set", mutable.BitSet.empty, mutable.HashSet.empty[Int], mutable.LinkedHashSet.empty[Int] ) property("an element can be added to an empty mutable Set") { forAll(examples) { set => info("----------------") Given("an empty mutable " + set.getClass.getSimpleName) assert(set.isEmpty) When("an element is added") set += 99 Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains(99)) } markup("This test finished with a **bold** statement!") } }
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.propspec.note import org.scalatest._ import prop._ import collection.mutable class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks { val examples = Table( "set", mutable.BitSet.empty, mutable.HashSet.empty[Int], mutable.LinkedHashSet.empty[Int] ) property("an element can be added to an empty mutable Set") { info("info is recorded") markup("markup is *also* recorded") note("notes are sent immediately") alert("alerts are also sent immediately") forAll(examples) { set => assert(set.isEmpty) set += 99 assert(set.size === 1) assert(set.contains(99)) } } }
Because note
and alert
information is sent immediately, it will appear before the test name in string reporters, and its color will
be unrelated to the ultimate outcome of the test: note
text will always appear in green, alert
text will always appear in yellow.
Here's an example:
scala> org.scalatest.run(new SetSpec) SetSpec: + notes are sent immediately + alerts are also sent immediately - an element can be added to an empty mutable Set + 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. 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.
(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.
You can mark tests pending in AnyPropSpec
like this:
import org.scalatest._ import prop._ import scala.collection.immutable._ class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with Matchers { val examples = Table( "set", BitSet.empty, HashSet.empty[Int], TreeSet.empty[Int] ) property("an empty Set should have size 0") (pending) property("invoking head on an empty set should produce NoSuchElementException") { forAll(examples) { set => a [NoSuchElementException] should be thrownBy { set.head } } } }
(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 SetSuite
with:
scala> org.scalatest.run(new SetSuite)
It will run both tests, but report that first test is pending. You'll see:
SetSuite: - An empty Set should have size 0 (pending) - Invoking head on an empty Set should produce NoSuchElementException
One difference between an ignored test and a pending one is that an ignored test is intended to be used during a 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
. The reason for this difference
is that it enables your unfinished test to send InfoProvided
messages to the reporter before it completes
abruptly with TestPendingException
, as shown in the previous example on Informer
s
that used the GivenWhenThen
trait.
A AnyPropSpec
's tests may be classified into groups by tagging them with string names.
As with any suite, when executing a AnyPropSpec
, groups of tests can
optionally be included and/or excluded. To tag a AnyPropSpec
'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 names,
com.mycompany.tags.DbTest
, then you could
create a matching tag for AnyPropSpec
s like this:
package org.scalatest.examples.propspec.tagging import org.scalatest.Tag object DbTest extends Tag("com.mycompany.tags.DbTest")
Given these definitions, you could place AnyPropSpec
tests into groups with tags like this:
import org.scalatest._ import prop._ import tagobjects.Slow import scala.collection.immutable._ class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with Matchers { val examples = Table( "set", BitSet.empty, HashSet.empty[Int], TreeSet.empty[Int] ) property("an empty Set should have size 0", Slow) { forAll(examples) { set => set.size should be (0) } } property("invoking head on an empty set should produce NoSuchElementException", Slow, DbTest) { forAll(examples) { set => a [NoSuchElementException] should be thrownBy { set.head } } } }
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.
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:
withFixture
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 more amenable for parallel
test execution.
The techniques in AnyPropSpec
are identical to those in FunSuite
, but with “test
”
replaced by “property
”. The following table summarizes the options with a link to the relevant
documentation for trait FunSuite
:
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. |
fixture-context objects | By placing fixture methods and fields into traits, you can easily give each test just the newly created fixtures it needs by mixing together traits. Use this technique when you need different combinations of mutable fixture objects in different tests, and don't need to clean up after. |
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(NoArgTest)
|
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(OneArgTest)
|
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. |
AnyPropSpec
to implement a test matrix Using fixture-context objects in a AnyPropSpec
is a good way to implement a test matrix.
What is the matrix? A test matrix is a series of tests that you need to run on a series of subjects. For example, The Scala API contains
many implementations of trait Set
. Every implementation must obey the contract of Set
.
One property of any Set
is that an empty Set
should have size 0, another is that
invoking head on an empty Set
should give you a NoSuchElementException
, and so on. Already you have a matrix,
where rows are the properties and the columns are the set implementations:
BitSet | HashSet | TreeSet | |
---|---|---|---|
An empty Set should have size 0 | pass | pass | pass |
Invoking head on an empty set should produce NoSuchElementException | pass | pass | pass |
One way to implement this test matrix is to define a trait to represent the columns (in this case, BitSet
, HashSet
,
and TreeSet
) as elements in a single-dimensional Table
. Each element in the Table
represents
one Set
implementation. Because different properties may require different fixture instances for those implementations, you
can define a trait to hold the examples, like this:
trait SetExamples extends Tables { def examples = Table("set", bitSet, hashSet, treeSet) def bitSet: BitSet def hashSet: HashSet[Int] def treeSet: TreeSet[Int] }
Given this trait, you could provide empty sets in one implementation of SetExamples
, and non-empty sets in another.
Here's how you might provide empty set examples:
class EmptySetExamples extends SetExamples { def bitSet = BitSet.empty def hashSet = HashSet.empty[Int] def treeSet = TreeSet.empty[Int] }
And here's how you might provide set examples with one item each:
class SetWithOneItemExamples extends SetExamples { def bitSet = BitSet(1) def hashSet = HashSet(1) def treeSet = TreeSet(1) }
Armed with these example classes, you can define checks of properties that require
empty or non-empty set fixtures by using instances of these classes as fixture-context
objects. In other words, the columns of the test matrix are implemented as elements of
a one-dimensional table of fixtures, the rows are implemented as property
clauses of a AnyPropSpec
.
Here's a complete example that checks the two properties mentioned previously:
package org.scalatest.examples.propspec.matrix import org.scalatest._ import org.scalatest.prop._ import scala.collection.immutable._ trait SetExamples extends Tables { def examples = Table("set", bitSet, hashSet, treeSet) def bitSet: BitSet def hashSet: HashSet[Int] def treeSet: TreeSet[Int] } class EmptySetExamples extends SetExamples { def bitSet = BitSet.empty def hashSet = HashSet.empty[Int] def treeSet = TreeSet.empty[Int] } class SetSpec extends propspec.AnyPropSpec with TableDrivenPropertyChecks with Matchers { property("an empty Set should have size 0") { new EmptySetExamples { forAll(examples) { set => set.size should be (0) } } } property("invoking head on an empty set should produce NoSuchElementException") { new EmptySetExamples { forAll(examples) { set => a [NoSuchElementException] should be thrownBy { set.head } } } } }
One benefit of this approach is that the compiler will help you when you need to add either a new row or column to the matrix. In either case, you'll need to ensure all cells are checked to get your code to compile.
Sometimes you may want to run the same test code on different fixture objects. That is to say, you may want to write tests that are "shared"
by different fixture objects.
You accomplish this in a AnyPropSpec
in the same way you would do it in a FunSuite
, except instead of test
you say property
, and instead of testsFor
you say propertiesFor
.
For more information, see the Shared tests section of FunSuite
's
documentation.
Implementation trait for class AnyPropSpec
, which represents
a suite of property-based tests.
Implementation trait for class AnyPropSpec
, which represents
a suite of property-based tests.
AnyPropSpec
is a class, not a trait,
to minimize compile time given there is a slight compiler overhead to
mixing in traits compared to extending classes. If you need to mix the
behavior of AnyPropSpec
into some other class, you can use this
trait instead, because class AnyPropSpec
does nothing more than
extend this trait and add a nice toString
implementation.
See the documentation of the class for a detailed
overview of AnyPropSpec
.
A sister class to org.scalatest.propspec.AnyPropSpec
that can pass a fixture object into its tests.
A sister class to org.scalatest.propspec.AnyPropSpec
that can pass a fixture object into its tests.
Recommended Usage:
Use class FixtureAnyPropSpec in situations for which AnyPropSpec
would be a good choice, when all or most tests need the same fixture objects
that must be cleaned up afterwards. Note: FixtureAnyPropSpec is intended for use in special
situations, with class AnyPropSpec used for general needs. For
more insight into where FixtureAnyPropSpec fits in the big picture, see
the withFixture(OneArgTest) subsection of
the Shared fixtures section in the documentation for class AnyPropSpec .
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Class FixtureAnyPropSpec
behaves similarly to class org.scalatest.propspec.AnyPropSpec
, except that tests may have a
fixture parameter. The type of the
fixture parameter is defined by the abstract FixtureParam
type, which is a member of this class.
This class also has an abstract withFixture
method. This withFixture
method
takes a OneArgTest
, which is a nested trait defined as a member of this class.
OneArgTest
has an apply
method that takes a FixtureParam
.
This apply
method is responsible for running a test.
This class's runTest
method delegates the actual running of each test to withFixture
, passing
in the test code to run via the OneArgTest
argument. The withFixture
method (abstract in this class) is responsible
for creating the fixture argument and passing it to the test function.
Subclasses of this class must, therefore, do three things differently from a plain old org.scalatest.propspec.AnyPropSpec
:
FixtureParam
withFixture(OneArgTest)
methodHere's an example:
package org.scalatest.examples.fixture.propspec import org.scalatest._ import prop.PropertyChecks import java.io._ class ExampleSpec extends propspec.FixtureAnyPropSpec with PropertyChecks with Matchers { // 1. define type FixtureParam type FixtureParam = FileReader // 2. define the withFixture method def withFixture(test: OneArgTest) = { val FileName = "TempFile.txt" // Set up the temp file needed by the test val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test val reader = new FileReader(FileName) try { // Run the test using the temp file test(reader) } finally { // Close and delete the temp file reader.close() val file = new File(FileName) file.delete() } } // 3. write property-based tests that take a fixture parameter // (Hopefully less contrived than the examples shown here.) property("can read from a temp file") { reader => var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } val fileContents = builder.toString forAll { (c: Char) => whenever (c != 'H') { fileContents should not startWith c.toString } } } property("can read the first char of the temp file") { reader => val firstChar = reader.read() forAll { (c: Char) => whenever (c != 'H') { c should not equal firstChar } } } // (You can also write tests that don't take a fixture parameter.) property("can write tests that don't take the fixture") { () => forAll { (i: Int) => i + i should equal (2 * i) } } }
Note: to run the examples on this page, you'll need to include ScalaCheck on the classpath in addition to ScalaTest.
In the previous example, withFixture
creates and initializes a temp file, then invokes the test function,
passing in a FileReader
connected to that file. In addition to setting up the fixture before a test,
the withFixture
method also cleans it up afterwards. If you need to do some clean up
that must happen even if a test fails, you should invoke the test function from inside a try
block and do
the cleanup in a finally
clause, as shown in the previous example.
If a test fails, the OneArgTest
function will result in a Failed wrapping the
exception describing the failure.
The reason you must perform cleanup in a finally
clause is that in case an exception propagates back through
withFixture
, the finally
clause will ensure the fixture cleanup happens as that exception
propagates back up the call stack to runTest
.
If a test doesn't need the fixture, you can indicate that by providing a no-arg instead of a one-arg function.
In other words, instead of starting your function literal
with something like “reader =>
”, you'd start it with “() =>
”, as is done
in the third test in the above example. For such tests, runTest
will not invoke withFixture(OneArgTest)
. It will instead directly invoke withFixture(NoArgTest)
.
If the fixture you want to pass into your tests consists of multiple objects, you will need to combine them into one object to use this class. One good approach to passing multiple fixture objects is to encapsulate them in a case class. Here's an example:
case class FixtureParam(builder: StringBuilder, buffer: ListBuffer[String])
To enable the stacking of traits that define withFixture(NoArgTest)
, it is a good idea to let
withFixture(NoArgTest)
invoke the test function instead of invoking the test
function directly. To do so, you'll need to convert the OneArgTest
to a NoArgTest
. You can do that by passing
the fixture object to the toNoArgTest
method of OneArgTest
. In other words, instead of
writing “test(theFixture)
”, you'd delegate responsibility for
invoking the test function to the withFixture(NoArgTest)
method of the same instance by writing:
withFixture(test.toNoArgTest(theFixture))
Here's a complete example:
package org.scalatest.examples.fixture.propspec.multi import org.scalatest._ import prop.PropertyChecks import scala.collection.mutable.ListBuffer class ExampleSpec extends propspec.FixtureAnyPropSpec with PropertyChecks with Matchers { case class FixtureParam(builder: StringBuilder, buffer: ListBuffer[String]) def withFixture(test: OneArgTest) = { // Create needed mutable objects val stringBuilder = new StringBuilder("ScalaTest is ") val listBuffer = new ListBuffer[String] val theFixture = FixtureParam(stringBuilder, listBuffer) // Invoke the test function, passing in the mutable objects withFixture(test.toNoArgTest(theFixture)) } property("testing should be easy") { f => f.builder.append("easy!") assert(f.builder.toString === "ScalaTest is easy!") assert(f.buffer.isEmpty) val firstChar = f.builder(0) forAll { (c: Char) => whenever (c != 'S') { c should not equal firstChar } } f.buffer += "sweet" } property("testing should be fun") { f => f.builder.append("fun!") assert(f.builder.toString === "ScalaTest is fun!") assert(f.buffer.isEmpty) val firstChar = f.builder(0) forAll { (c: Char) => whenever (c != 'S') { c should not equal firstChar } } } }
Implementation trait for class FixtureAnyPropSpec
, which is
a sister class to org.scalatest.propspec.AnyPropSpec
that can pass a
fixture object into its tests.
Implementation trait for class FixtureAnyPropSpec
, which is
a sister class to org.scalatest.propspec.AnyPropSpec
that can pass a
fixture object into its tests.
FixtureAnyPropSpec
is a class,
not a trait, to minimize compile time given there is a slight compiler
overhead to mixing in traits compared to extending classes. If you need
to mix the behavior of FixtureAnyPropSpec
into some other
class, you can use this trait instead, because class
FixtureAnyPropSpec
does nothing more than extend this trait and add a nice toString
implementation.
See the documentation of the class for a detailed
overview of FixtureAnyPropSpec
.
Classes and traits for ScalaTest's
PropSpec
style.This package is released as the
scalatest-propspec
module.