org.scalatest.fixture

trait FixtureSpec

[source: org/scalatest/fixture/FixtureSpec.scala]

trait FixtureSpec
extends FixtureSuite
A sister trait to org.scalatest.Spec, which passes a fixture object into each test.

This trait behaves similarly to trait org.scalatest.Spec, except that tests may take a fixture object. The type of the fixture object passed is defined by the abstract Fixture type, which is declared as a member of this trait (inherited from supertrait FixtureSuite). This trait also inherits the abstract method withFixture from supertrait FixtureSuite. The withFixture method takes a OneArgTest, which is a nested trait defined as a member of supertrait FixtureSuite. OneArgTest has an apply method that takes a Fixture. This apply method is responsible for running a test. This trait'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 trait) is responsible for creating the fixture and passing it to the test function.

Subclasses of this trait must, therefore, do three things differently from a plain old org.scalatest.Spec:

  1. define the type of the fixture object by specifying type Fixture
  2. define the withFixture method
  3. write tests that take a Fixture (You can also define tests that don't take a Fixture.)

Here's an example:

 import org.scalatest.fixture.FixtureSpec
 import java.io.FileReader
 import java.io.FileWriter
 import java.io.File
 
 class MySpec extends FixtureSpec {

   // 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 tests that take a fixture parameter
   it("should read from the temp file") { reader =>
     var builder = new StringBuilder
     var c = reader.read()
     while (c != -1) {
       builder.append(c.toChar)
       c = reader.read()
     }
     assert(builder.toString === "Hello, test!")
   }
 
   it("should read the first char of the temp file") { reader =>
     assert(reader.read() === 'H')
   }
 
   // (You can also write tests that don't take a fixture parameter.)
   it("should work without a fixture") { () =>
       assert(1 + 1 === 2)
   }
 }
 

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 trait. One good approach to passing multiple fixture objects is to encapsulate them in a tuple. Here's an example that takes the tuple approach:

 import org.scalatest.fixture.FixtureSpec
 import scala.collection.mutable.ListBuffer

 class MySpec extends FixtureSpec {

   type FixtureParam = (StringBuilder, ListBuffer[String])

   def withFixture(test: OneArgTest) {

     // Create needed mutable objects
     val stringBuilder = new StringBuilder("ScalaTest is ")
     val listBuffer = new ListBuffer[String]

     // Invoke the test function, passing in the mutable objects
     test(stringBuilder, listBuffer)
   }

   it("should mutate shared fixture objects") { fixture =>
     val (builder, buffer) = fixture
     builder.append("easy!")
     assert(builder.toString === "ScalaTest is easy!")
     assert(buffer.isEmpty)
     buffer += "sweet"
   }

   it("should get a fresh set of mutable fixture objects") { fixture =>
     val (builder, buffer) = fixture
     builder.append("fun!")
     assert(builder.toString === "ScalaTest is fun!")
     assert(buffer.isEmpty)
   }
 }
 

When using a tuple to pass multiple fixture objects, it is usually helpful to give names to each individual object in the tuple with a pattern-match assignment, as is done at the beginning of each test here with:

 val (builder, buffer) = fixture
 

Another good approach to passing multiple fixture objects is to encapsulate them in a case class. Here's an example that takes the case class approach:

 import org.scalatest.fixture.FixtureSpec
 import scala.collection.mutable.ListBuffer

 class MySpec extends FixtureSpec {

   case class FixtureHolder(builder: StringBuilder, buffer: ListBuffer[String])

   type FixtureParam = FixtureHolder

   def withFixture(test: OneArgTest) {

     // Create needed mutable objects
     val stringBuilder = new StringBuilder("ScalaTest is ")
     val listBuffer = new ListBuffer[String]

     // Invoke the test function, passing in the mutable objects
     test(FixtureHolder(stringBuilder, listBuffer))
   }

   it("should mutate shared fixture objects") { fixture =>
     import fixture._
     builder.append("easy!")
     assert(builder.toString === "ScalaTest is easy!")
     assert(buffer.isEmpty)
     buffer += "sweet"
   }

   it("should get a fresh set of mutable fixture objects") { fixture =>
     fixture.builder.append("fun!")
     assert(fixture.builder.toString === "ScalaTest is fun!")
     assert(fixture.buffer.isEmpty)
   }
 }
 

When using a case class to pass multiple fixture objects, it can be helpful to make the names of each individual object available as a single identifier with an import statement. This is the approach taken by the testEasy method in the previous example. Because it imports the members of the fixture object, the test code can just use them as unqualified identifiers:

 it("should mutate shared fixture objects") { fixture =>
   import fixture._
   builder.append("easy!")
   assert(builder.toString === "ScalaTest is easy!")
   assert(buffer.isEmpty)
   buffer += "sweet"
 }
 

Alternatively, you may sometimes prefer to qualify each use of a fixture object with the name of the fixture parameter. This approach, taken by the testFun method in the previous example, makes it more obvious which variables in your test are part of the passed-in fixture:

 it("should mutate shared fixture objects") { fixture =>
   fixture.builder.append("fun!")
   assert(fixture.builder.toString === "ScalaTest is fun!")
   assert(fixture.buffer.isEmpty)
 }
 

Configuring fixtures and tests

Sometimes you may want to write tests that are configurable. For example, you may want to write a suite of tests that each take an open temp file as a fixture, but whose file name is specified externally so that the file name can be can be changed from run to run. To accomplish this the OneArgTest trait has a configMap method, which will return a Map[String, Any] from which configuration information may be obtained. The runTest method of this trait will pass a OneArgTest to withFixture whose configMap method returns the configMap passed to runTest. Here's an example in which the name of a temp file is taken from the passed configMap:

 import org.scalatest.fixture.FixtureSpec
 import java.io.FileReader
 import java.io.FileWriter
 import java.io.File
 
 class MySpec extends FixtureSpec {

   type FixtureParam = FileReader

   def withFixture(test: OneArgTest) {

     require(
       test.configMap.contains("TempFileName"),
       "This suite requires a TempFileName to be passed in the configMap"
     )

     // Grab the file name from the configMap
     val FileName = test.configMap("TempFileName")

     // 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()
     }
   }
 
   test("reading from the temp file") { reader =>
     var builder = new StringBuilder
     var c = reader.read()
     while (c != -1) {
       builder.append(c.toChar)
       c = reader.read()
     }
     assert(builder.toString === "Hello, test!")
   }
 
   test("first char of the temp file") { reader =>
     assert(reader.read() === 'H')
   }
 }
 

If you want to pass into each test the entire configMap that was passed to runTest, you can mix in trait ConfigMapFixture. See the documentation for ConfigMapFixture for the details, but here's a quick example of how it looks:

  import org.scalatest.fixture.FixtureSpec
  import org.scalatest.fixture.ConfigMapFixture

  class MySpec extends FixtureSpec with ConfigMapFixture {

    it("should contain hello") { configMap =>
      // Use the configMap passed to runTest in the test
      assert(configMap.contains("hello")
    }

    it("should contain world") { configMap =>
      assert(configMap.contains("world")
    }
  }
 

ConfigMapFixture can also be used to facilitate writing FixtureSpecs that include tests that take different fixture types. See the documentation for MultipleFixtureSpec for more information.

Author
Bill Venners
Direct Known Subclasses:
MultipleFixtureSpec

Value Summary
protected val behave : BehaveWord
Supports shared test registration in FixtureSpecs.
protected val it : ItWord
Supports test (and shared test) registration in FixtureSpecs.
Method Summary
protected implicit def convertNoArgToFixtureFunction (fun : () => Any) : (FixtureParam) => Any
Implicitly converts a function that takes no parameters and results in Any to a function from Fixture to Any, to enable no-arg tests to registered by methods that require a test function that takes a Fixture.
protected implicit def convertPendingToFixtureFunction (f : => PendingNothing) : (FixtureParam) => Any
Implicitly converts a function that takes no parameters and results in PendingNothing to a function from Fixture to Any, to enable pending tests to registered as by-name parameters by methods that require a test function that takes a Fixture.
protected def describe (description : java.lang.String)(f : => Unit) : Unit
Describe a “subject” being specified and tested by the passed function value. The passed function value may contain more describers (defined with describe) and/or tests (defined with it). This trait's implementation of this method will register the description string and immediately invoke the passed function.
protected def ignore (specText : java.lang.String, testTags : Tag*)(testFun : (FixtureParam) => Any) : Unit
Register a test to ignore, which has the given spec text, optional tags, and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected def ignore (specText : java.lang.String)(testFun : (FixtureParam) => Any) : Unit
Register a test to ignore, which has the given spec text and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected implicit def info : Informer
Returns an Informer that during test execution will forward strings (and other objects) 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 FixtureSpec 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 throw an exception. This method can be called safely by any thread.
override def run (testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Runs this suite of tests.
protected override def runTest (testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
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 documenation for testNames for an example.)
protected override def runTests (testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
override def tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A Map whose keys are String tag names to which tests in this Spec belong, and values the Set of test names that belong to each tag. If this Spec contains no tags, this method returns an empty Map.
override def testNames : scala.collection.immutable.Set[java.lang.String]
An immutable Set of test names. If this FixtureFeatureSpec contains no tests, this method returns an empty Set.
Methods inherited from Suite
nestedSuites, execute, execute, execute, execute, groups, withFixture, runNestedSuites, suiteName, pending, pendingUntilFixed, expectedTestCount
Methods inherited from Assertions
assert, assert, assert, assert, convertToEqualizer, intercept, expect, expect, fail, fail, fail, fail
Methods inherited from AnyRef
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Methods inherited from FixtureSuite
withFixture (abstract)
Class Summary
protected final class ItWord extends AnyRef
Class that, via an instance referenced from the it field, supports test (and shared test) registration in FixtureSpecs.
Value Details
protected val it : ItWord
Supports test (and shared test) registration in FixtureSpecs.

This field supports syntax such as the following:

   it("should be empty")
   ^
   
   it should behave like nonFullStack(stackWithOneItem)
   ^
   

For more information and examples of the use of the it field, see the main documentation for Spec.


protected val behave : BehaveWord
Supports shared test registration in FixtureSpecs.

This field supports syntax such as the following:

   it should behave like nonFullStack(stackWithOneItem)
             ^
   

For more information and examples of the use of behave, see the Shared tests section in the main documentation for trait Spec.


Method Details
protected implicit def info : Informer
Returns an Informer that during test execution will forward strings (and other objects) 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 FixtureSpec 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 throw an exception. This method can be called safely by any thread.

protected def ignore(specText : java.lang.String, testTags : Tag*)(testFun : (FixtureParam) => Any) : Unit
Register a test to ignore, which has the given spec text, optional tags, and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
Parameters
specText - the specification text, which will be combined with the descText of any surrounding describers to form the test name
testTags - the optional list of tags for this test
testFun - the test function
Throws
DuplicateTestNameException - if a test with the same name has been registered previously
TestRegistrationClosedException - if invoked after run has been invoked on this suite
NullPointerException - if specText or any passed test tag is null

protected def ignore(specText : java.lang.String)(testFun : (FixtureParam) => Any) : Unit
Register a test to ignore, which has the given spec text and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
Parameters
specText - the specification text, which will be combined with the descText of any surrounding describers to form the test name
testFun - the test function
Throws
DuplicateTestNameException - if a test with the same name has been registered previously
TestRegistrationClosedException - if invoked after run has been invoked on this suite
NullPointerException - if specText or any passed test tag is null

protected def describe(description : java.lang.String)(f : => Unit) : Unit
Describe a “subject” being specified and tested by the passed function value. The passed function value may contain more describers (defined with describe) and/or tests (defined with it). This trait's implementation of this method will register the description string and immediately invoke the passed function.

override def tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A Map whose keys are String tag names to which tests in this Spec belong, and values the Set of test names that belong to each tag. If this Spec 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 methods test and ignore.

Overrides
FixtureSuite.tags

protected override def runTest(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
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 documenation for testNames for an example.)
Parameters
testName - the name of one test to execute.
reporter - the Reporter to which results will be reported
stopper - the Stopper that will be consulted to determine whether to stop execution early.
configMap - a Map of properties that can be used by this Spec's executing tests.
Throws
NullPointerException - if any of testName, reporter, stopper, or configMap is null.
Overrides
FixtureSuite.runTest

protected override def runTests(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit

Run zero to many of this Spec'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 - the String value of the testName Option passed to this method
  • reporter - the Reporter passed to this method, or one that wraps and delegates to it
  • stopper - the Stopper passed to this method, or one that wraps and delegates to it
  • configMap - the configMap 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 Sets. If so, this implementation invokes runTest, passing in:

  • testName - the String name of the test to run (which will be one of the names in the testNames Set)
  • reporter - the Reporter passed to this method, or one that wraps and delegates to it
  • stopper - the Stopper passed to this method, or one that wraps and delegates to it
  • configMap - the configMap passed to this method, or one that wraps and delegates to it
Parameters
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 this Spec.
reporter - the Reporter to which results will be reported
stopper - the Stopper that will be consulted to determine whether to stop execution early.
tagsToInclude - a Set of String tag names to include in the execution of this Spec
tagsToExclude - a Set of String tag names to exclude in the execution of this Spec
configMap - a Map of key-value pairs that can be used by this Spec's executing tests.
Throws
NullPointerException - if any of testName, reporter, stopper, tagsToInclude, tagsToExclude, or configMap is null.

override def testNames : scala.collection.immutable.Set[java.lang.String]
An immutable Set of test names. If this FixtureFeatureSpec 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.

Overrides
FixtureSuite.testNames

override def run(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Runs this suite of tests.

If testName is None, this trait's implementation of this method calls these two methods on this object in this order:

  1. runNestedSuites(report, stopper, tagsToInclude, tagsToExclude, configMap, distributor)
  2. runTests(testName, report, stopper, tagsToInclude, tagsToExclude, configMap)

If testName is defined, then this trait's implementation of this method calls runTests, but does not call runNestedSuites. This behavior is part of the contract of this method. Subclasses that override run must take care not to call runNestedSuites if testName is defined. (The OneInstancePerTest trait depends on this behavior, for example.)

Subclasses and subtraits that override this run method can implement them without invoking either the runTests or runNestedSuites methods, which are invoked by this trait's implementation of this method. It is recommended, but not required, that subclasses and subtraits that override run in a way that does not invoke runNestedSuites also override runNestedSuites and make it final. Similarly it is recommended, but not required, that subclasses and subtraits that override run in a way that does not invoke runTests also override runTests (and runTest, which this trait's implementation of runTests calls) and make it final. The implementation of these final methods can either invoke the superclass implementation of the method, or throw an UnsupportedOperationException if appropriate. The reason for this recommendation is that ScalaTest includes several traits that override these methods to allow behavior to be mixed into a Suite. For example, trait BeforeAndAfterEach overrides runTestss. In a Suite subclass that no longer invokes runTests from run, the BeforeAndAfterEach trait is not applicable. Mixing it in would have no effect. By making runTests final in such a Suite subtrait, you make the attempt to mix BeforeAndAfterEach into a subclass of your subtrait a compiler error. (It would fail to compile with a complaint that BeforeAndAfterEach is trying to override runTests, which is a final method in your trait.)

Parameters
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 this Suite.
reporter - the Reporter to which results will be reported
stopper - the Stopper that will be consulted to determine whether to stop execution early.
filter - a Filter with which to filter tests based on their tags
configMap - a Map of key-value pairs that can be used by the executing Suite of tests.
distributor - an optional Distributor, into which to put nested Suites to be run by another entity, such as concurrently by a pool of threads. If None, nested Suites will be run sequentially.
tracker - a Tracker tracking Ordinals being fired by the current thread.
Throws
NullPointerException - if any passed parameter is null.
IllegalArgumentException - if testName is defined, but no test with the specified test name exists in this Suite

protected implicit def convertPendingToFixtureFunction(f : => PendingNothing) : (FixtureParam) => Any
Implicitly converts a function that takes no parameters and results in PendingNothing to a function from Fixture to Any, to enable pending tests to registered as by-name parameters by methods that require a test function that takes a Fixture.

This method makes it possible to write pending tests as simply (pending), without needing to write (fixture => pending).


protected implicit def convertNoArgToFixtureFunction(fun : () => Any) : (FixtureParam) => Any
Implicitly converts a function that takes no parameters and results in Any to a function from Fixture to Any, to enable no-arg tests to registered by methods that require a test function that takes a Fixture.


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