OneInstancePerTest
Trait that facilitates a style of testing in which each test is run in its own instance of the suite class to isolate each test from the side effects of the other tests in the suite.
Recommended Usage: Trait OneInstancePerTest is intended primarily to serve as a supertrait for ParallelTestExecution and the path traits, to facilitate porting JUnit tests to ScalaTest, and to make it easy for users who prefer JUnit's approach to isolation to obtain similar behavior in ScalaTest. |
If you mix this trait into a Suite
, you can initialize shared reassignable fixture variables as well as shared mutable fixture objects in the constructor of the class. Because each test will run in its own instance of the class, each test will get a fresh copy of the instance variables. This is the approach to test isolation taken, for example, by the JUnit framework. OneInstancePerTest
can, therefore, be handy when porting JUnit tests to ScalaTest.
Here's an example of OneInstancePerTest
being used in a FunSuite
:
import org.scalatest.FunSuite import org.scalatest.OneInstancePerTest import collection.mutable.ListBuffer class MySuite extends FunSuite with OneInstancePerTest { val builder = new StringBuilder("ScalaTest is ") val buffer = new ListBuffer[String] test("easy") { builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(buffer.isEmpty) buffer += "sweet" } test("fun") { builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(buffer.isEmpty) } }
OneInstancePerTest
is supertrait to ParallelTestExecution
, in which running each test in its own instance is intended to make it easier to write suites of tests that run in parallel (by reducing the likelihood of concurrency bugs in those suites.) OneInstancePerTest
is also supertrait to the path traits, path.FunSpec
and path.FreeSpec
, to make it obvious these traits run each test in a new, isolated instance.
For the details on how OneInstancePerTest
works, see the documentation for methods runTests
and runTest
, which this trait overrides.
Attributes
- Graph
-
- Supertypes
- Known subtypes
-
trait ParallelTestExecutiontrait RandomTestOrder
- Self type
Members list
Value members
Abstract methods
Construct a new instance of this Suite
.
Construct a new instance of this Suite
.
This trait's implementation of runTests
invokes this method to create a new instance of this Suite
for each test. This trait's implementation of this method uses reflection to call this.getClass.newInstance
. This approach will succeed only if this Suite
's class has a public, no-arg constructor. In most cases this is likely to be true, because to be instantiated by ScalaTest's Runner
a Suite
needs a public, no-arg constructor. However, this will not be true of any Suite
defined as an inner class of another class or trait, because every constructor of an inner class type takes a reference to the enclosing instance. In such cases, and in cases where a Suite
class is explicitly defined without a public, no-arg constructor, you will need to override this method to construct a new instance of the Suite
in some other way.
Here's an example of how you could override newInstance
to construct a new instance of an inner class:
import org.scalatest.Suite class Outer { class InnerSuite extends Suite with OneInstancePerTest { def testOne() {} def testTwo() {} override def newInstance = new InnerSuite } }
Attributes
Concrete methods
Modifies the behavior of super.runTest
to facilitate running each test in its own instance of this Suite
's class.
Modifies the behavior of super.runTest
to facilitate running each test in its own instance of this Suite
's class.
This trait's implementation of runTest
uses the runTestInNewInstance
flag of the passed Args
object to determine whether this instance is the general instance responsible for running all tests in the suite (runTestInNewInstance
is true
), or a test-specific instance responsible for running just one test (runTestInNewInstance
is false
). Note that these Boolean
values are reverse those used by runTests
, because runTests
always inverts the Boolean
value of runTestInNewInstance
when invoking runTest
.
If runTestInNewInstance
is true
, this trait's implementation of this method creates a new instance of this class (by invoking newInstance
on itself), then invokes run
on the new instance, passing in testName
, wrapped in a Some
, and args
unchanged. (I.e., the Args
object passed to runTest
is forwarded as is to run
on the new instance, including with runTestInNewInstance
set.) If the invocation of either newInstance
on this Suite
or run
on a newly created instance of this Suite
completes abruptly with an exception, then this runTests
method will complete abruptly with the same exception.
If runTestInNewInstance
is false
, this trait's implementation of this method simply invokes super.runTest
, passing along the same testName
and args
objects.
Value parameters
- args
-
the
Args
for this run - testName
-
the name of one test to execute.
Attributes
- Returns
-
a
Status
object that indicates when the test started by this method has completed, and whether or not it failed .
Modifies the behavior of super.runTests
to facilitate running each test in its own instance of this Suite
's class.
Modifies the behavior of super.runTests
to facilitate running each test in its own instance of this Suite
's class.
This trait's implementation of runTest
uses the runTestInNewInstance
flag of the passed Args
object to determine whether this instance is the general instance responsible for running all tests in the suite (runTestInNewInstance
is false
), or a test-specific instance responsible for running just one test (runTestInNewInstance
is true
). Note that these Boolean
values are reverse those used by runTest
, because runTests
always inverts the Boolean
value of runTestInNewInstance
when invoking runTest
.
If runTestInNewInstance
is false
, this trait's implementation of this method will invoke super.runTests
, passing along testName
and args
, but with the runTestInNewInstance
flag set to true
. By setting runTestInNewInstance
to true
, runTests
is telling runTest
to create a new instance to run each test.
If runTestInNewInstance
is true
, this trait's implementation of this method will invoke runTest
directly, passing in testName.get
and the args
object, with the runTestInNewInstance
flag set to false
. By setting runTestInNewInstance
to false
, runTests
is telling runTest
that this is the test-specific instance, so it should just run the specified test.
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
.
Attributes
- 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
, or ifrunTestInNewInstance
istrue
, buttestName
is empty.NullPointerExceptionif any of the passed parameters is
null
.
Inherited methods
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.
Value parameters
- filter
-
a
Filter
with which to filter tests to count based on their tags
Attributes
- Inherited from:
- SuiteMixin
An immutable IndexedSeq
of this SuiteMixin
object's nested Suite
s. If this SuiteMixin
contains no nested Suite
s, this method returns an empty IndexedSeq
.
An immutable IndexedSeq
of this SuiteMixin
object's nested Suite
s. If this SuiteMixin
contains no nested Suite
s, this method returns an empty IndexedSeq
.
Attributes
- Inherited from:
- SuiteMixin
The fully qualified name of the class that can be used to rerun this suite.
The fully qualified name of the class that can be used to rerun this suite.
Attributes
- Inherited from:
- SuiteMixin
Runs this suite of tests.
Runs this suite of tests.
Value parameters
- args
-
the
Args
for this run - testName
-
an optional name of one test to execute. If
None
, all relevant tests should be executed. I.e.,None
acts like a wildcard that means execute all relevant tests in thisSuite
.
Attributes
- Returns
-
a
Status
object that indicates when all tests and nested suites started by this method have completed, and whether or not a failure occurred. - Throws
-
NullArgumentException
if any passed parameter is
null
. - Inherited from:
- SuiteMixin
Runs zero to many of this suite's nested suites.
Runs zero to many of this suite's nested suites.
Value parameters
- args
-
the
Args
for this run
Attributes
- Returns
-
a
Status
object that indicates when all nested suites started by this method have completed, and whether or not a failure occurred. - Throws
-
NullArgumentException
if
args
isnull
. - Inherited from:
- SuiteMixin
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.
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.
Attributes
- Returns
-
this
Suite
object's ID. - Inherited from:
- SuiteMixin
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
.
Attributes
- Returns
-
this
Suite
object's suite name. - Inherited from:
- SuiteMixin
A Map
whose keys are String
names of tagged tests and whose associated values are the Set
of tag names for the test. If a test has no associated tags, its name does not appear as a key in the returned Map
. If this Suite
contains no tests with 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 tag names for the test. If a test has no associated tags, its name does not appear as a key in the returned Map
. If this Suite
contains no tests with tags, this method returns an empty Map
.
Subclasses may override this method to define and/or discover tags in a custom manner, but overriding method implementations should never return an empty Set
as a value. If a test has no tags, its name should not appear as a key in the returned Map
.
Attributes
- Inherited from:
- SuiteMixin
Provides a TestData
instance for the passed test name, given the passed config map.
Provides a TestData
instance for the passed test name, given the passed config map.
This method is used to obtain a TestData
instance to pass to withFixture(NoArgTest)
and withFixture(OneArgTest)
and the beforeEach
and afterEach
methods of trait BeforeAndAfterEach
.
Value parameters
- testName
-
the name of the test for which to return a
TestData
instance - theConfigMap
-
the config map to include in the returned
TestData
Attributes
- Returns
-
a
TestData
instance for the specified test, which includes the specified config map - Inherited from:
- SuiteMixin
A Set
of test names. If this Suite
contains no tests, this method returns an empty Set
.
A Set
of test names. If this Suite
contains no tests, this method returns an empty Set
.
Although subclass and subtrait implementations of this method may return a Set
whose iterator produces String
test names in a well-defined order, the contract of this method does not required a defined order. Subclasses are free to implement this method and return test names in either a defined or undefined order.
Attributes
- Inherited from:
- SuiteMixin