Type Members

1.  class AnyPropSpec extends AnyPropSpecLike

   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.

   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.

   Ignored tests

   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
   

   Informers

   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
   

   Documenters

   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:

   

   Notifiers and alerters

   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.)

   Pending tests

   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 Informers that used the GivenWhenThen trait.

   Tagging tests

   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 AnyPropSpecs 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.

   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:

   • 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 vars, 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: Different tests need different fixtures (refactor using Scala instead) An exception in fixture code should abort the suite, not fail the test (use a before-and-after trait instead) You have objects to pass into tests (override withFixture(OneArgTest) instead)
   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.

   Using 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.

   Shared tests

   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.

2.  trait AnyPropSpecLike extends TestSuite with TestRegistration with Informing with Notifying with Alerting with Documenting

   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.

3.  abstract class FixtureAnyPropSpec extends FixtureAnyPropSpecLike

   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.

   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:

   • define the type of the fixture parameter by specifying type FixtureParam
   • define the withFixture(OneArgTest) method
   • write tests that take a fixture parameter
   • (You can also define tests that don't take a fixture parameter.)

   Here'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).

   Passing multiple fixture objects

   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
         }
       }
     }
   }
   

4.  trait FixtureAnyPropSpecLike extends fixture.TestSuite with fixture.TestRegistration with Informing with Notifying with Alerting with Documenting

   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.