org.scalatest

FlatSpec

trait FlatSpec extends Suite with ShouldVerb with MustVerb with CanVerb

Trait that facilitates a “behavior-driven” style of development (BDD), in which tests are combined with text that specifies the behavior the tests verify. (In BDD, the word example is usually used instead of test. The word test will not appear in your code if you use FlatSpec, so if you prefer the word example you can use it. However, in this documentation the word test will be used, for clarity and to be consistent with the rest of ScalaTest.) Trait FlatSpec is so named because your specification text and tests line up flat against the left-side indentation level, with no nesting needed.

FlatSpec's no-nesting approach contrasts with traits Spec and WordSpec, which use nesting to reduce duplication of specification text. Although nesting does have the advantage of reducing text duplication, figuring out the full specification text for one test can require back-tracking out of several levels of nesting, mentally prepending each fragment of text encountered. Thus the tradeoff with the nesting approach of Spec and WordSpec is that they have less duplicated text at the cost of being a bit challenging to read. Trait FlatSpec offers the opposite tradeoff. In a FlatSpec text is duplicated more, but figuring out the full specification text for a particular test is easier. Here's an example FlatSpec:

import org.scalatest.FlatSpec
import scala.collection.mutable.Stack

class StackSpec extends FlatSpec {

  behavior of "A Stack"

  it should "pop values in last-in-first-out order" in {
    val stack = new Stack[Int]
    stack.push(1)
    stack.push(2)
    assert(stack.pop() === 2)
    assert(stack.pop() === 1)
  }

  it should "throw NoSuchElementException if an empty stack is popped" in {
    val emptyStack = new Stack[String]
    intercept[NoSuchElementException] {
      emptyStack.pop()
    }
  }
}

Note: you can you must or can as well as should in a FlatSpec. For example, instead of it should "pop..., you could write it must "pop... or it can "pop....

Instead of using a behavior of clause, you can alternatively use a shorthand syntax in which you replace the first it with the subject string, like this:

import org.scalatest.FlatSpec
import scala.collection.mutable.Stack

class StackSpec extends FlatSpec {

  "A Stack" should "pop values in last-in-first-out order" in {
    val stack = new Stack[Int]
    stack.push(1)
    stack.push(2)
    assert(stack.pop() === 2)
    assert(stack.pop() === 1)
  }

  it should "throw NoSuchElementException if an empty stack is popped" in {
    val emptyStack = new Stack[String]
    intercept[NoSuchElementException] {
      emptyStack.pop()
    }
  }
}

Running either of the two previous three versions of StackSpec in the Scala interpreter would yield:

A Stack
- should pop values in last-in-first-out order
- should throw NoSuchElementException if an empty stack is popped

In a FlatSpec you write a one (or more) sentence specification for each bit of behavior you wish to specify and test. Each specification sentence has a "subject," which is sometimes called the system under test (or SUT). The subject is the entity being specified and tested and also serves as the subject of the sentences you write for each test. Often you will want to write multiple tests for the same subject. In a FlatSpec, you name the subject once, with a behavior of clause or its shorthand, then write tests for that subject with it should/mustcan "do something" phrases. Each it refers to the most recently declared subject. For example, the four tests shown in this snippet are all testing a stack that contains one item:

behavior of "A Stack (with one item)"

it should "be non-empty" in {}

it should "return the top item on peek" in {}

it should "not remove the top item on peek" in {}

it should "remove the top item on pop" in {}

The same is true if the tests are written using the shorthand notation:

"A Stack (with one item)" should "be non-empty" in {}

it should "return the top item on peek" in {}

it should "not remove the top item on peek" in {}

it should "remove the top item on pop" in {}

In a FlatSpec, therefore, to figure out what "it" means, you just scan vertically until you find the most recent use of behavior of or the shorthand notation.

A FlatSpec'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 while the FlatSpec is in its registration phase. Any attempt to register a test after the FlatSpec has entered its ready phase, i.e., after run has been invoked on the FlatSpec, will be met with a thrown TestRegistrationClosedException. The recommended style of using FlatSpec 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.

Shared fixtures

A test fixture is objects or other artifacts (such as files, sockets, database connections, etc.) used by tests to do their work. You can use fixtures in FlatSpecs with the same approaches suggested for Suite in its documentation. The same text that appears in the test fixture section of Suite's documentation is repeated here, with examples changed from Suite to FlatSpec.

If a fixture is used by only one test, then the definitions of the fixture objects can be local to the test function, such as the objects assigned to stack and emptyStack in the previous StackSpec examples. If multiple tests need to share an immutable fixture, one approach is to assign them to instance variables. Here's a (very contrived) example, in which the object assigned to shared is used by multiple test functions:

import org.scalatest.FlatSpec

class ArithmeticSpec extends FlatSpec {

  // Sharing immutable fixture objects via instance variables
  val shared = 5

 "The Scala language" must "add correctly" in {
    val sum = 2 + 3
    assert(sum === shared)
  }

  it must "subtract correctly" in {
    val diff = 7 - 2
    assert(diff === shared)
  }
}

In some cases, however, shared mutable fixture objects may be changed by tests such that they need to be recreated or reinitialized before each test. Shared resources such as files or database connections may also need to be created and initialized before, and cleaned up after, each test. JUnit offers methods setUp and tearDown for this purpose. In ScalaTest, you can use the BeforeAndAfterEach trait, which will be described later, to implement an approach similar to JUnit's setUp and tearDown, however, this approach often involves reassigning vars between tests. Before going that route, you should consider some approaches that avoid vars. One approach is to write one or more create-fixture methods that return a new instance of a needed object (or a tuple or case class holding new instances of multiple objects) each time it is called. You can then call a create-fixture method at the beginning of each test that needs the fixture, storing the fixture object or objects in local variables. Here's an example:

import org.scalatest.FlatSpec
import scala.collection.mutable.ListBuffer

class MySuite extends FlatSpec {

  // create objects needed by tests and return as a tuple
  def createFixture = (
    new StringBuilder("ScalaTest is "),
    new ListBuffer[String]
  )

 "ScalaTest" can "be easy " in {
    val (builder, lbuf) = createFixture
    builder.append("easy!")
    assert(builder.toString === "ScalaTest is easy!")
    assert(lbuf.isEmpty)
    lbuf += "sweet"
  }

  it can "be fun" in {
    val (builder, lbuf) = createFixture
    builder.append("fun!")
    assert(builder.toString === "ScalaTest is fun!")
    assert(lbuf.isEmpty)
  }
}

If different tests in the same FlatSpec require different fixtures, you can create multiple create-fixture methods and call the method (or methods) needed by each test at the begining of the test. If every test requires the same set of mutable fixture objects, one other approach you can take is make them simply vals and mix in trait OneInstancePerTest. If you mix in OneInstancePerTest, each test will be run in its own instance of the FlatSpec, similar to the way JUnit tests are executed.

Although the create-fixture and OneInstancePerTest approaches take care of setting up a fixture before each test, they don't address the problem of cleaning up a fixture after the test completes. In this situation, one option is to mix in the BeforeAndAfterEach trait. BeforeAndAfterEach's beforeEach method will be run before, and its afterEach method after, each test (like JUnit's setUp and tearDown methods, respectively). For example, you could create a temporary file before each test, and delete it afterwords, like this:

import org.scalatest.FlatSpec
import org.scalatest.BeforeAndAfterEach
import java.io.FileReader
import java.io.FileWriter
import java.io.File

class MySuite extends FlatSpec with BeforeAndAfterEach {

  private val FileName = "TempFile.txt"
  private var reader: FileReader = _

  // Set up the temp file needed by the test
  override def beforeEach() {
    val writer = new FileWriter(FileName)
    try {
      writer.write("Hello, test!")
    }
    finally {
      writer.close()
    }

    // Create the reader needed by the test
    reader = new FileReader(FileName)
  }

  // Close and delete the temp file
  override def afterEach() {
    reader.close()
    val file = new File(FileName)
    file.delete()
  }

 "A FileReader" should "read in the contents of a file correctly" in {
    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 in the first character of a file correctly" in {
    assert(reader.read() === 'H')
  }

  it should "work without a fixture" in {
    assert(1 + 1 === 2)
  }
}

In this example, the instance variable reader is a var, so it can be reinitialized between tests by the beforeEach method.

Although the BeforeAndAfterEach approach should be familiar to the users of most test other frameworks, ScalaTest provides another alternative that also allows you to perform cleanup after each test: overriding withFixture(NoArgTest). To execute each test, Suite's implementation of the runTest method wraps an invocation of the appropriate test method in a no-arg function. runTest passes that test function to the withFixture(NoArgTest) method, which is responsible for actually running the test by invoking the function. Suite's implementation of withFixture(NoArgTest) simply invokes the function, like this:

// Default implementation
protected def withFixture(test: NoArgTest) {
  test()
}

The withFixture(NoArgTest) method exists so that you can override it and set a fixture up before, and clean it up after, each test. Thus, the previous temp file example could also be implemented without mixing in BeforeAndAfterEach, like this:

import org.scalatest.FlatSpec
import org.scalatest.BeforeAndAfterEach
import java.io.FileReader
import java.io.FileWriter
import java.io.File

class MySuite extends FlatSpec {

  private var reader: FileReader = _

  override def withFixture(test: NoArgTest) {

    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
    reader = new FileReader(FileName)

    try {
      test() // Invoke the test function
    }
    finally {
      // Close and delete the temp file
      reader.close()
      val file = new File(FileName)
      file.delete()
    }
  }

 "A FileReader" should "read in the contents of a file correctly" in {
    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 in the first character of a file correctly" in {
    assert(reader.read() === 'H')
  }

  it should "work without a fixture" in {
    assert(1 + 1 === 2)
  }
}

If you prefer to keep your test classes immutable, one final variation is to use the FixtureFlatSpec trait from the org.scalatest.fixture package. Tests in an org.scalatest.fixture.FixtureFlatSpec can have a fixture object passed in as a parameter. You must indicate the type of the fixture object by defining the Fixture type member and define a withFixture method that takes a one-arg test function. (A FixtureFlatSpec has two overloaded withFixture methods, therefore, one that takes a OneArgTest and the other, inherited from Suite, that takes a NoArgTest.) Inside the withFixture(OneArgTest) method, you create the fixture, pass it into the test function, then perform any necessary cleanup after the test function returns. Instead of invoking each test directly, a FixtureFlatSpec will pass a function that invokes the code of a test to withFixture(OneArgTest). Your withFixture(OneArgTest) method, therefore, is responsible for actually running the code of the test by invoking the test function. For example, you could pass the temp file reader fixture to each test that needs it by overriding the withFixture(OneArgTest) method of a FixtureFlatSpec, like this:

import org.scalatest.fixture.FixtureFlatSpec
import java.io.FileReader
import java.io.FileWriter
import java.io.File

class MySuite extends FixtureFlatSpec {

  type FixtureParam = FileReader

  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()
    }
  }

 "A FileReader" should "read in the contents of a file correctly" in { 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 in the first character of a file correctly" in { reader =>
    assert(reader.read() === 'H')
  }

  it should "work without a fixture" in { () =>
    assert(1 + 1 === 2)
  }
}

It is worth noting that the only difference in the test code between the mutable BeforeAndAfterEach approach shown here and the immutable FixtureFlatSpec approach shown previously is that two of the FixtureFlatSpec's test functions take a FileReader as a parameter via the "reader =>" at the beginning of the function. Otherwise the test code is identical. One benefit of the explicit parameter is that, as demonstrated by the "it should work without a fixture" test, a FixtureFlatSpec test need not take the fixture. So you can have some tests that take a fixture, and others that don't. In this case, the FixtureFlatSpec provides documentation indicating which tests use the fixture and which don't, whereas the BeforeAndAfterEach approach does not. (If you have want to combine tests that take different fixture types in the same FlatSpec, you can use MultipleFixtureFlatSpec.)

If you want to execute code before and after all tests (and nested suites) in a suite, such as you could do with @BeforeClass and @AfterClass annotations in JUnit 4, you can use the beforeAll and afterAll methods of BeforeAndAfterAll. See the documentation for BeforeAndAfterAll for an example.

Shared tests

Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared" by different fixture objects. To accomplish this in a FlatSpec, you first place shared tests in behavior functions. These behavior functions will be invoked during the construction phase of any FlatSpec that uses them, so that the tests they contain will be registered as tests in that FlatSpec. For example, given this stack class:

import scala.collection.mutable.ListBuffer

class Stack[T] {

  val MAX = 10
  private var buf = new ListBuffer[T]

  def push(o: T) {
    if (!full)
      o +: buf
    else
      throw new IllegalStateException("can't push onto a full stack")
  }

  def pop(): T = {
    if (!empty)
      buf.remove(0)
    else
      throw new IllegalStateException("can't pop an empty stack")
  }

  def peek: T = {
    if (!empty)
      buf(0)
    else
      throw new IllegalStateException("can't pop an empty stack")
  }

  def full: Boolean = buf.size == MAX
  def empty: Boolean = buf.size == 0
  def size = buf.size

  override def toString = buf.mkString("Stack(", ", ", ")")
}

You may want to test the Stack class in different states: empty, full, with one item, with one item less than capacity, etc. You may find you have several tests that make sense any time the stack is non-empty. Thus you'd ideally want to run those same tests for three stack fixture objects: a full stack, a stack with a one item, and a stack with one item less than capacity. With shared tests, you can factor these tests out into a behavior function, into which you pass the stack fixture to use when running the tests. So in your FlatSpec for stack, you'd invoke the behavior function three times, passing in each of the three stack fixtures so that the shared tests are run for all three fixtures. You can define a behavior function that encapsulates these shared tests inside the FlatSpec that uses them. If they are shared between different FlatSpecs, however, you could also define them in a separate trait that is mixed into each FlatSpec that uses them.

For example, here the nonEmptyStack behavior function (in this case, a behavior method) is defined in a trait along with another method containing shared tests for non-full stacks:

trait StackBehaviors { this: FlatSpec =>

  def nonEmptyStack(stack: Stack[Int], lastItemAdded: Int) {

    it should "be non-empty" in {
      assert(!stack.empty)
    }

    it should "return the top item on peek" in {
      assert(stack.peek === lastItemAdded)
    }

    it should "not remove the top item on peek" in {
      val size = stack.size
      assert(stack.peek === lastItemAdded)
      assert(stack.size === size)
    }

    it should "remove the top item on pop" in {
      val size = stack.size
      assert(stack.pop === lastItemAdded)
      assert(stack.size === size - 1)
    }
  }

  def nonFullStack(stack: Stack[Int]) {

    it should "not be full" in {
      assert(!stack.full)
    }

    it should "add to the top on push" in {
      val size = stack.size
      stack.push(7)
      assert(stack.size === size + 1)
      assert(stack.peek === 7)
    }
  }
}

Given these behavior functions, you could invoke them directly, but FlatSpec offers a DSL for the purpose, which looks like this:

it should behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
it should behave like nonFullStack(stackWithOneItem)

If you prefer to use an imperative style to change fixtures, for example by mixing in BeforeAndAfterEach and reassigning a stack var in beforeEach, you could write your behavior functions in the context of that var, which means you wouldn't need to pass in the stack fixture because it would be in scope already inside the behavior function. In that case, your code would look like this:

it should behave like nonEmptyStack // assuming lastValuePushed is also in scope inside nonEmptyStack
it should behave like nonFullStack

The recommended style, however, is the functional, pass-all-the-needed-values-in style. Here's an example:

class SharedTestExampleSpec extends FlatSpec with StackBehaviors {

  // Stack fixture creation methods
  def emptyStack = new Stack[Int]

  def fullStack = {
    val stack = new Stack[Int]
    for (i <- 0 until stack.MAX)
      stack.push(i)
    stack
  }

  def stackWithOneItem = {
    val stack = new Stack[Int]
    stack.push(9)
    stack
  }

  def stackWithOneItemLessThanCapacity = {
    val stack = new Stack[Int]
    for (i <- 1 to 9)
      stack.push(i)
    stack
  }

  val lastValuePushed = 9

  "A Stack (when empty)" should "be empty" in {
    assert(emptyStack.empty)
  }

  it should "complain on peek" in {
    intercept[IllegalStateException] {
      emptyStack.peek
    }
  }

  it should "complain on pop" in {
    intercept[IllegalStateException] {
      emptyStack.pop
    }
  }

  "A Stack (with one item)" should behave like nonEmptyStack(stackWithOneItem, lastValuePushed)

  it should behave like nonFullStack(stackWithOneItem)

  "A Stack (with one item less than capacity)" should behave like nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed)

  it should behave like nonFullStack(stackWithOneItemLessThanCapacity)

  "A Stack (full)" should "be full" in {
    assert(fullStack.full)
  }

  it should behave like nonEmptyStack(fullStack, lastValuePushed)

  it should "complain on a push" in {
    intercept[IllegalStateException] {
      fullStack.push(10)
    }
  }
}

If you load these classes into the Scala interpreter (with scalatest's JAR file on the class path), and execute it, you'll see:

scala> (new SharedTestExampleSpec).execute()
A Stack (when empty)
- should be empty
- should complain on peek
- should complain on pop
A Stack (with one item)
- should be non-empty
- should return the top item on peek
- should not remove the top item on peek
- should remove the top item on pop
- should not be full
- should add to the top on push
A Stack (with one item less than capacity)
- should be non-empty
- should return the top item on peek
- should not remove the top item on peek
- should remove the top item on pop
- should not be full
- should add to the top on push
A Stack (full)
- should be full
- should be non-empty
- should return the top item on peek
- should not remove the top item on peek
- should remove the top item on pop
- should complain on a push

One thing to keep in mind when using shared tests is that in ScalaTest, each test in a suite must have a unique name. If you register the same tests repeatedly in the same suite, one problem you may encounter is an exception at runtime complaining that multiple tests are being registered with the same test name. A good way to solve this problem in a WordSpec is to make sure each invocation of a behavior function is in the context of a different set of when, verb (should, must, or can), and that clauses, which will prepend a string to each test name. For example, the following code in a WordSpec would register a test with the name "A Stack (when empty) should be empty":

  behavior of "A Stack (when empty)"

  it should "be empty" in {
    assert(emptyStack.empty)
  }
  // ...

Or, using the shorthand notation:

  "A Stack" when {
    "empty" should {
      "be empty" in {
        assert(emptyStack.empty)
      }
    }
  }
  // ...

If the "should be empty" test was factored out into a behavior function, it could be called repeatedly so long as each invocation of the behavior function is in the context of a different combination of when, verb, and that clauses.

Tagging tests

A FlatSpec's tests may be classified into groups by tagging them with string names. As with any suite, when executing a FlatSpec, groups of tests can optionally be included and/or excluded. To tag a FlatSpec's tests, you pass objects that extend abstract class org.scalatest.Tag to taggedAs method invoked on the string that describes the test you want to tag. Class Tag takes one parameter, a string name. If you have created Java annotation interfaces for use as group names in direct subclasses of org.scalatest.Suite, then you will probably want to use group names on your FlatSpecs that match. To do so, simply pass the fully qualified names of the Java interfaces to the Tag constructor. For example, if you've defined Java annotation interfaces with fully qualified names, com.mycompany.groups.SlowTest and com.mycompany.groups.DbTest, then you could create matching groups for Specs like this:

import org.scalatest.Tag

object SlowTest extends Tag("com.mycompany.groups.SlowTest")
object DbTest extends Tag("com.mycompany.groups.DbTest")

Given these definitions, you could place FlatSpec tests into groups like this:

import org.scalatest.FlatSpec

class MySuite extends FlatSpec {

  "The Scala language" must "add correctly" taggedAs(SlowTest) in {
      val sum = 1 + 1
      assert(sum === 2)
      assert(sum + 2 === 4)
    }

  it must "subtract correctly" taggedAs(SlowTest, DbTest) in {
    val diff = 4 - 1
    assert(diff === 3)
    assert(diff - 2 === 1)
  }
}

This code marks both tests with the com.mycompany.groups.SlowTest tag, and test "The Scala language should subtract correctly" with the com.mycompany.groups.DbTest tag.

The primary run method takes a Filter, whose constructor takes an optional Set[String]s 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.

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, FlatSpec provides a method ignore that can be used instead of it to register a test. For example, to temporarily disable the test with the name "A Stack should throw NoSuchElementException if an empty stack is popped", just change “it” into “ignore,” like this:

import org.scalatest.FlatSpec
import scala.collection.mutable.Stack

class StackSpec extends FlatSpec {

  "A Stack" should "pop values in last-in-first-out order" in {
      val stack = new Stack[Int]
      stack.push(1)
      stack.push(2)
      assert(stack.pop() === 2)
      assert(stack.pop() === 1)
    }

  ignore should "throw NoSuchElementException if an empty stack is popped" in {
    val emptyStack = new Stack[String]
    intercept[NoSuchElementException] {
      emptyStack.pop()
    }
  }
}

If you run this version of StackSpec with:

scala> (new StackSpec).execute()

It will run only the first test and report that the second test was ignored:

A Stack
- should pop values in last-in-first-out order
- should throw NoSuchElementException if an empty stack is popped !!! IGNORED !!!

When using shorthand notation, you won't have an it to change into ignore for the first test of each new subject. To ignore such tests, you must instead change in to ignore. For example, to temporarily disable the test with the name "A Stack should pop values in last-in-first-out order", change “in” into “ignore” like this:

import org.scalatest.FlatSpec
import scala.collection.mutable.Stack

class StackSpec extends FlatSpec {

  "A Stack" should "pop values in last-in-first-out order" ignore {
      val stack = new Stack[Int]
      stack.push(1)
      stack.push(2)
      assert(stack.pop() === 2)
      assert(stack.pop() === 1)
    }

  it should "throw NoSuchElementException if an empty stack is popped" in {
    val emptyStack = new Stack[String]
    intercept[NoSuchElementException] {
      emptyStack.pop()
    }
  }
}

If you run this version of StackSpec with:

scala> (new StackSpec).execute()

It will run only the second test and report that the first test was ignored:

A Stack
- should pop values in last-in-first-out order !!! IGNORED !!!
- should throw NoSuchElementException if an empty stack is popped

Informers

One of the parameters to the primary 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 FlatSpec'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:

import org.scalatest.FlatSpec

class ArithmeticSpec extends FlatSpec {

 "The Scala language" must "add correctly" in {
    val sum = 2 + 3
    assert(sum === 5)
    info("addition seems to work")
  }

  it must "subtract correctly" in {
    val diff = 7 - 2
    assert(diff === 5)
  }
}

If you run this FlatSpec from the interpreter, you will see the following message included in the printed report:

scala> (new ArithmeticSpec).execute()
The Scala language
- must add correctly
  + addition seems to work
- must subtract correctly

One use case for the Informer is to pass more information about a specification to the reporter. For example, the GivenWhenThen trait provides methods that use the implicit info provided by FlatSpec to pass such information to the reporter. Here's an example:

import org.scalatest.FlatSpec
import org.scalatest.GivenWhenThen

class ArithmeticSpec extends FlatSpec with GivenWhenThen {

 "The Scala language" must "add correctly" in {

    given("two integers")
    val x = 2
    val y = 3

    when("they are added")
    val sum = x + y

    then("the result is the sum of the two numbers")
    assert(sum === 5)
  }

  it must "subtract correctly" in {

    given("two integers")
    val x = 7
    val y = 2

    when("one is subtracted from the other")
    val diff = x - y

    then("the result is the difference of the two numbers")
    assert(diff === 5)
  }
}

scala> (new ArithmeticSpec).execute()
The Scala language
- must add correctly
  + Given two integers
  + When they are added
  + Then the result is the sum of the two numbers
- must subtract correctly
  + Given two integers
  + When one is subtracted from the other
  + Then the result is the difference of the two numbers

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, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.

To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. The test can also include some code that sends more information about the behavior to the reporter when the tests run. At the end of the test, it can call method pending, which will cause it to complete abruptly with TestPendingException. Because tests in ScalaTest can be designated as pending with TestPendingException, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (In other words, the code of a pending test is executed just like any other test.) However, because the test completes abruptly with TestPendingException, the test will be reported as pending, to indicate the actual test, and possibly the functionality it is intended to test, has not yet been implemented. You can mark tests as pending in FlatSpec like this:

import org.scalatest.FlatSpec

class ArithmeticSpec extends FlatSpec {

  // Sharing fixture objects via instance variables
  val shared = 5

 "The Scala language" must "add correctly" in {
    val sum = 2 + 3
    assert(sum === shared)
  }

  it must "subtract correctly" is (pending)
}

If you run this version of ArithmeticSpec with:

scala> (new ArithmeticSpec).execute()

It will run both tests but report that The Scala language must subtract correctly is pending. You'll see:

The Scala language
- must add correctly
- must subtract correctly (pending)

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. For example, the following snippet in a FlatSpec:

 "The Scala language" must "add correctly" in {
    given("two integers")
    when("they are added")
    then("the result is the sum of the two numbers")
    pending
  }
  // ...

Would yield the following output when run in the interpreter:

The Scala language
- must add correctly (pending)
  + Given two integers
  + When they are added
  + Then the result is the sum of the two numbers

Self Type
FlatSpec
Linear Supertypes
Ordering
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Inherited
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  1. FlatSpec
  2. CanVerb
  3. MustVerb
  4. ShouldVerb
  5. Suite
  6. AbstractSuite
  7. Assertions
  8. AnyRef
  9. Any
Visibility
  1. Public
  2. All

Type Members

  1. class BehaviorWord extends AnyRef

    Class that supports the registration of a “subject” being specified and tested via the instance referenced from FlatSpec's behavior field.

  2. class Equalizer extends AnyRef

    Class used via an implicit conversion to enable any two objects to be compared with === in assertions in tests.

  3. class IgnoreVerbString extends AnyRef

    Class that supports registration of ignored tests via the IgnoreWord instance referenced from FlatSpec's ignore field.

  4. class IgnoreVerbStringTaggedAs extends AnyRef

    Class that supports registration of ignored, tagged tests via the IgnoreWord instance referenced from FlatSpec's ignore field.

  5. class IgnoreWord extends AnyRef

    Class that supports registration of ignored tests via the ItWord instance referenced from FlatSpec's ignore field.

  6. class InAndIgnoreMethods extends AnyRef

    Class that supports test registration in shorthand form.

  7. class InAndIgnoreMethodsAfterTaggedAs extends AnyRef

    Class that supports tagged test registration in shorthand form.

  8. class ItVerbString extends AnyRef

    Class that supports test registration via the ItWord instance referenced from FlatSpec's it field.

  9. class ItVerbStringTaggedAs extends AnyRef

    Class that supports the registration of tagged tests via the ItWord instance referenced from FlatSpec's it field.

  10. class ItWord extends AnyRef

    Class that supports test (and shared test) registration via the instance referenced from FlatSpec's it field.

  11. trait NoArgTest extends () ⇒ Unit

    A test function taking no arguments, which also provides a test name and config map.

  12. class StringCanWrapperForVerb extends AnyRef

    This class supports the syntax of FlatSpec, WordSpec, FixtureFlatSpec, and FixtureWordSpec.

  13. class StringMustWrapperForVerb extends AnyRef

    This class supports the syntax of FlatSpec, WordSpec, FixtureFlatSpec, and FixtureWordSpec.

  14. class StringShouldWrapperForVerb extends AnyRef

    This class supports the syntax of FlatSpec, WordSpec, FixtureFlatSpec, and FixtureWordSpec.

Value Members

  1. def != (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  2. def != (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any
  3. def ## (): Int

    Attributes
    final
    Definition Classes
    AnyRef → Any
  4. def == (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  5. def == (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any
  6. def asInstanceOf [T0] : T0

    Attributes
    final
    Definition Classes
    Any
  7. def assert (o: Option[String]): Unit

    Assert that an Option[String] is None.

    Assert that an Option[String] is None. If the condition is None, this method returns normally. Else, it throws TestFailedException with the String value of the Some included in the TestFailedException's detail message.

    This form of assert is usually called in conjunction with an implicit conversion to Equalizer, using a === comparison, as in:

    assert(a === b)
    

    For more information on how this mechanism works, see the documentation for Equalizer.

    o

    the Option[String] to assert

    Definition Classes
    Assertions
  8. def assert (o: Option[String], clue: Any): Unit

    Assert that an Option[String] is None.

    Assert that an Option[String] is None. If the condition is None, this method returns normally. Else, it throws TestFailedException with the String value of the Some, as well as the String obtained by invoking toString on the specified message, included in the TestFailedException's detail message.

    This form of assert is usually called in conjunction with an implicit conversion to Equalizer, using a === comparison, as in:

    assert(a === b, "extra info reported if assertion fails")
    

    For more information on how this mechanism works, see the documentation for Equalizer.

    o

    the Option[String] to assert

    clue

    An objects whose toString method returns a message to include in a failure report.

    Definition Classes
    Assertions
  9. def assert (condition: Boolean, clue: Any): Unit

    Assert that a boolean condition, described in String message, is true.

    Assert that a boolean condition, described in String message, is true. If the condition is true, this method returns normally. Else, it throws TestFailedException with the String obtained by invoking toString on the specified message as the exception's detail message.

    condition

    the boolean condition to assert

    clue

    An objects whose toString method returns a message to include in a failure report.

    Definition Classes
    Assertions
  10. def assert (condition: Boolean): Unit

    Assert that a boolean condition is true.

    Assert that a boolean condition is true. If the condition is true, this method returns normally. Else, it throws TestFailedException.

    condition

    the boolean condition to assert

    Definition Classes
    Assertions
  11. val behave : BehaveWord

    Supports shared test registration in FlatSpecs.

    Supports shared test registration in FlatSpecs.

    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 this trait.

    Attributes
    protected
  12. val behavior : BehaviorWord

    Supports the registration of a “subject” being specified and tested.

    Supports the registration of a “subject” being specified and tested.

    This field enables syntax such as the following subject registration:

    behavior of "A Stack"
    ^
    

    For more information and examples of the use of the behavior field, see the main documentation for this trait.

    Attributes
    protected
  13. def clone (): AnyRef

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  14. implicit def convertToEqualizer (left: Any): Equalizer

    Implicit conversion from Any to Equalizer, used to enable assertions with === comparisons.

    Implicit conversion from Any to Equalizer, used to enable assertions with === comparisons.

    For more information on this mechanism, see the documentation for Equalizer.

    Because trait Suite mixes in Assertions, this implicit conversion will always be available by default in ScalaTest Suites. This is the only implicit conversion that is in scope by default in every ScalaTest Suite. Other implicit conversions offered by ScalaTest, such as those that support the matchers DSL or invokePrivate, must be explicitly invited into your test code, either by mixing in a trait or importing the members of its companion object. The reason ScalaTest requires you to invite in implicit conversions (with the exception of the implicit conversion for === operator) is because if one of ScalaTest's implicit conversions clashes with an implicit conversion used in the code you are trying to test, your program won't compile. Thus there is a chance that if you are ever trying to use a library or test some code that also offers an implicit conversion involving a === operator, you could run into the problem of a compiler error due to an ambiguous implicit conversion. If that happens, you can turn off the implicit conversion offered by this convertToEqualizer method simply by overriding the method in your Suite subclass, but not marking it as implicit:

    // In your Suite subclass
    override def convertToEqualizer(left: Any) = new Equalizer(left)
    

    left

    the object whose type to convert to Equalizer.

    Attributes
    implicit
    Definition Classes
    Assertions
  15. implicit def convertToInAndIgnoreMethods (resultOfStringPassedToVerb: ResultOfStringPassedToVerb): InAndIgnoreMethods

    Implicitly converts an object of type ResultOfStringPassedToVerb to an InAndIgnoreMethods, to enable in and ignore methods to be invokable on that object.

    Implicitly converts an object of type ResultOfStringPassedToVerb to an InAndIgnoreMethods, to enable in and ignore methods to be invokable on that object.

    Attributes
    protected implicit
  16. implicit def convertToInAndIgnoreMethodsAfterTaggedAs (resultOfTaggedAsInvocation: ResultOfTaggedAsInvocation): InAndIgnoreMethodsAfterTaggedAs

    Implicitly converts an object of type ResultOfTaggedAsInvocation to an InAndIgnoreMethodsAfterTaggedAs, to enable in and ignore methods to be invokable on that object.

    Implicitly converts an object of type ResultOfTaggedAsInvocation to an InAndIgnoreMethodsAfterTaggedAs, to enable in and ignore methods to be invokable on that object.

    Attributes
    protected implicit
  17. implicit def convertToStringCanWrapper (o: String): StringCanWrapperForVerb

    Implicitly converts an object of type String to a StringCanWrapper, to enable can methods to be invokable on that object.

    Implicitly converts an object of type String to a StringCanWrapper, to enable can methods to be invokable on that object.

    Attributes
    implicit
    Definition Classes
    CanVerb
  18. implicit def convertToStringMustWrapper (o: String): StringMustWrapperForVerb

    Implicitly converts an object of type String to a StringMustWrapper, to enable must methods to be invokable on that object.

    Implicitly converts an object of type String to a StringMustWrapper, to enable must methods to be invokable on that object.

    Attributes
    implicit
    Definition Classes
    MustVerb
  19. implicit def convertToStringShouldWrapper (o: String): StringShouldWrapperForVerb

    Implicitly converts an object of type String to a StringShouldWrapperForVerb, to enable should methods to be invokable on that object.

    Implicitly converts an object of type String to a StringShouldWrapperForVerb, to enable should methods to be invokable on that object.

    Attributes
    implicit
    Definition Classes
    ShouldVerb
  20. def eq (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  21. def equals (arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  22. def execute (testName: String = null, configMap: Map[String, Any] = Map(), color: Boolean = true, durations: Boolean = false, shortStacks: Boolean = false, fullStacks: Boolean = false, stats: Boolean = false): Unit

    Executes one or more tests in this Suite, printing results to the standard output.

    Executes one or more tests in this Suite, printing results to the standard output.

    This method invokes run on itself, passing in values that can be configured via the parameters to this method, all of which have default values. This behavior is convenient when working with ScalaTest in the Scala interpreter. Here's a summary of this method's parameters and how you can use them:

    The testName parameter

    If you leave testName at its default value (of null), this method will pass None to the testName parameter of run, and as a result all the tests in this suite will be executed. If you specify a testName, this method will pass Some(testName) to run, and only that test will be run. Thus to run all tests in a suite from the Scala interpreter, you can write:

    scala> (new MySuite).execute()
    

    To run just the test named "my favorite test" in a suite from the Scala interpreter, you would write:

    scala> (new MySuite).execute("my favorite test")
    

    Or:

    scala> (new MySuite).execute(testName = "my favorite test")
    

    The configMap parameter

    If you provide a value for the configMap parameter, this method will pass it to run. If not, the default value of an empty Map will be passed. For more information on how to use a config map to configure your test suites, see the config map section in the main documentation for this trait. Here's an example in which you configure a run with the name of an input file:

    scala> (new MySuite).execute(configMap = Map("inputFileName" -> "in.txt")
    

    The color parameter

    If you leave the color parameter unspecified, this method will configure the reporter it passes to run to print to the standard output in color (via ansi escape characters). If you don't want color output, specify false for color, like this:

    scala> (new MySuite).execute(color = false)
    

    The durations parameter

    If you leave the durations parameter unspecified, this method will configure the reporter it passes to run to not print durations for tests and suites to the standard output. If you want durations printed, specify true for durations, like this:

    scala> (new MySuite).execute(durations = true)
    

    The shortStacks and fullStacks parameters

    If you leave both the shortStacks and fullStacks parameters unspecified, this method will configure the reporter it passes to run to not print stack traces for failed tests if it has a stack depth that identifies the offending line of test code. If you prefer a short stack trace (10 to 15 stack frames) to be printed with any test failure, specify true for shortStacks:

    scala> (new MySuite).execute(shortStacks = true)
    

    For full stack traces, set fullStacks to true:

    scala> (new MySuite).execute(fullStacks = true)
    

    If you specify true for both shortStacks and fullStacks, you'll get full stack traces.

    The stats parameter

    If you leave the stats parameter unspecified, this method will not fire RunStarting and either RunCompleted or RunAborted events to the reporter it passes to run. If you specify true for stats, this method will fire the run events to the reporter, and the reporter will print the expected test count before the run, and various statistics after, including the number of suites completed and number of tests that succeeded, failed, were ignored or marked pending. Here's how you get the stats:

    scala> (new MySuite).execute(stats = true)
    

    To summarize, this method will pass to run:

    • testName - None if this method's testName parameter is left at its default value of null, else Some(testName).
    • reporter - a reporter that prints to the standard output
    • stopper - a Stopper whose apply method always returns false
    • filter - a Filter constructed with None for tagsToInclude and Set() for tagsToExclude
    • configMap - the configMap passed to this method
    • distributor - None
    • tracker - a new Tracker

    Note: In ScalaTest, the terms "execute" and "run" basically mean the same thing and can be used interchangably. One reason this method isn't named run is because junit.framework.TestCase declares a run method that takes no arguments but returns a junit.framework.TestResult. That run method would not overload with this method if it were named run, because it would have the same parameters but a different return type than the one defined in TestCase. To facilitate integration with JUnit 3, therefore, this "run" method is named execute. In particular, this allows trait org.scalatest.junit.JUnit3Suite to extend both org.scalatest.Suite and junit.framework.TestCase, which enables the creating of classes that can be run with either ScalaTest or JUnit 3, as is done with org.scalatest.junit.JUnit3Suite. The other reason this method isn't named run is that it takes advantage of default arguments, and you can't mix overloaded methods and default arguments in Scala. (If named run, this method would have the same name but different arguments than the main run method that takes seven arguments. Thus it would overload and couldn't be used with default argument values.)

    testName

    the name of one test to run.

    configMap

    a Map of key-value pairs that can be used by the executing Suite of tests.

    color

    a boolean that configures whether output is printed in color

    durations

    a boolean that configures whether test and suite durations are printed to the standard output

    shortStacks

    a boolean that configures whether short stack traces should be printed for test failures

    fullStacks

    a boolean that configures whether full stack traces should be printed for test failures

    stats

    a boolean that configures whether test and suite statistics are printed to the standard output

    Attributes
    final
    Definition Classes
    Suite
  23. def expect (expected: Any)(actual: Any): Unit

    Expect that the value passed as expected equals the value passed as actual.

    Expect that the value passed as expected equals the value passed as actual. If the actual value equals the expected value (as determined by ==), expect returns normally. Else, expect throws an TestFailedException whose detail message includes the expected and actual values.

    expected

    the expected value

    actual

    the actual value, which should equal the passed expected value

    Definition Classes
    Assertions
  24. def expect (expected: Any, clue: Any)(actual: Any): Unit

    Expect that the value passed as expected equals the value passed as actual.

    Expect that the value passed as expected equals the value passed as actual. If the actual equals the expected (as determined by ==), expect returns normally. Else, if actual is not equal to expected, expect throws an TestFailedException whose detail message includes the expected and actual values, as well as the String obtained by invoking toString on the passed message.

    expected

    the expected value

    clue

    An object whose toString method returns a message to include in a failure report.

    actual

    the actual value, which should equal the passed expected value

    Definition Classes
    Assertions
  25. def expectedTestCount (filter: Filter): Int

    The total number of tests that are expected to run when this Suite's run method is invoked.

    The total number of tests that are expected to run when this Suite's run method is invoked.

    This trait's implementation of this method returns the sum of:

    • the size of the testNames List, minus the number of tests marked as ignored
    • the sum of the values obtained by invoking expectedTestCount on every nested Suite contained in nestedSuites
    filter

    a Filter with which to filter tests to count based on their tags

    Definition Classes
    SuiteAbstractSuite
  26. def fail (cause: Throwable): Nothing

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed.

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed. The getMessage method of the thrown TestFailedException will return cause.toString().

    cause

    a Throwable that indicates the cause of the failure.

    Definition Classes
    Assertions
  27. def fail (message: String, cause: Throwable): Nothing

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    message

    A message describing the failure.

    cause

    A Throwable that indicates the cause of the failure.

    Definition Classes
    Assertions
  28. def fail (message: String): Nothing

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed.

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed.

    message

    A message describing the failure.

    Definition Classes
    Assertions
  29. def fail (): Nothing

    Throws TestFailedException to indicate a test failed.

    Throws TestFailedException to indicate a test failed.

    Definition Classes
    Assertions
  30. def finalize (): Unit

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  31. def getClass (): java.lang.Class[_]

    Attributes
    final
    Definition Classes
    AnyRef
  32. def hashCode (): Int

    Definition Classes
    AnyRef → Any
  33. val ignore : IgnoreWord

    Supports registration of ignored tests in FlatSpecs.

    Supports registration of ignored tests in FlatSpecs.

    This field enables syntax such as the following registration of an ignored test:

    ignore should "pop values in last-in-first-out order" in { ... }
    ^
    

    For more information and examples of the use of the ignore field, see the Ignored tests section in the main documentation for this trait.

    Attributes
    protected
  34. 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.

    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 FlatSpec 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.

    Attributes
    protected implicit
  35. def intercept [T <: AnyRef] (f: ⇒ Any)(implicit manifest: Manifest[T]): T

    Intercept and return an exception that's expected to be thrown by the passed function value.

    Intercept and return an exception that's expected to be thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns that exception. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throws TestFailedException.

    Note that the type specified as this method's type parameter may represent any subtype of AnyRef, not just Throwable or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such as String, for example), this method will complete abruptly with a TestFailedException.

    f

    the function value that should throw the expected exception

    manifest

    an implicit Manifest representing the type of the specified type parameter.

    returns

    the intercepted exception, if it is of the expected type

    Definition Classes
    Assertions
  36. def isInstanceOf [T0] : Boolean

    Attributes
    final
    Definition Classes
    Any
  37. val it : ItWord

    Supports test (and shared test) registration in FlatSpecs.

    Supports test (and shared test) registration in FlatSpecs.

    This field enables syntax such as the following test registration:

    it should "pop values in last-in-first-out order" in { ... }
    ^
    

    It also enables syntax such as the following shared test registration:

    it should behave like nonEmptyStack(lastItemPushed)
    ^
    

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

    Attributes
    protected
  38. def ne (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  39. def nestedSuites : List[Suite]

    A List of this Suite object's nested Suites.

    A List of this Suite object's nested Suites. If this Suite contains no nested Suites, this method returns an empty List. This trait's implementation of this method returns an empty List.

    Definition Classes
    SuiteAbstractSuite
  40. def notify (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
  41. def notifyAll (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
  42. def pending : PendingNothing

    Throws TestPendingException to indicate a test is pending.

    Throws TestPendingException to indicate a test is pending.

    A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.

    To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. The test can also include some code that sends more information about the behavior to the reporter when the tests run. At the end of the test, it can call method pending, which will cause it to complete abruptly with TestPendingException. Because tests in ScalaTest can be designated as pending with TestPendingException, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (In other words, the code of a pending test is executed just like any other test.) However, because the test completes abruptly with TestPendingException, the test will be reported as pending, to indicate the actual test, and possibly the functionality it is intended to test, has not yet been implemented.

    Note: This method always completes abruptly with a TestPendingException. Thus it always has a side effect. Methods with side effects are usually invoked with parentheses, as in pending(). This method is defined as a parameterless method, in flagrant contradiction to recommended Scala style, because it forms a kind of DSL for pending tests. It enables tests in suites such as FunSuite or Spec to be denoted by placing "(pending)" after the test name, as in:

    test("that style rules are not laws") (pending)
    

    Readers of the code see "pending" in parentheses, which looks like a little note attached to the test name to indicate it is pending. Whereas "(pending()) looks more like a method call, "(pending)" lets readers stay at a higher level, forgetting how it is implemented and just focusing on the intent of the programmer who wrote the code.

    Definition Classes
    Suite
  43. def pendingUntilFixed (f: ⇒ Unit): Unit

    Execute the passed block of code, and if it completes abruptly, throw TestPendingException, else throw TestFailedException.

    Execute the passed block of code, and if it completes abruptly, throw TestPendingException, else throw TestFailedException.

    This method can be used to temporarily change a failing test into a pending test in such a way that it will automatically turn back into a failing test once the problem originally causing the test to fail has been fixed. At that point, you need only remove the pendingUntilFixed call. In other words, a pendingUntilFixed surrounding a block of code that isn't broken is treated as a test failure. The motivation for this behavior is to encourage people to remove pendingUntilFixed calls when there are no longer needed.

    This method facilitates a style of testing in which tests are written before the code they test. Sometimes you may encounter a test failure that requires more functionality than you want to tackle without writing more tests. In this case you can mark the bit of test code causing the failure with pendingUntilFixed. You can then write more tests and functionality that eventually will get your production code to a point where the original test won't fail anymore. At this point the code block marked with pendingUntilFixed will no longer throw an exception (because the problem has been fixed). This will in turn cause pendingUntilFixed to throw TestFailedException with a detail message explaining you need to go back and remove the pendingUntilFixed call as the problem orginally causing your test code to fail has been fixed.

    f

    a block of code, which if it completes abruptly, should trigger a TestPendingException

    Definition Classes
    Suite
  44. def run (testName: Option[String], reporter: Reporter, stopper: Stopper, filter: Filter, configMap: Map[String, Any], distributor: Option[Distributor], tracker: Tracker): Unit

    Runs this suite of tests.

    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:

    • runNestedSuites(report, stopper, tagsToInclude, tagsToExclude, configMap, distributor)
    • 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.)

    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.

    Definition Classes
    FlatSpecSuiteAbstractSuite
  45. def runNestedSuites (reporter: Reporter, stopper: Stopper, filter: Filter, configMap: Map[String, Any], distributor: Option[Distributor], tracker: Tracker): Unit

    Run zero to many of this Suite's nested Suites.

    Run zero to many of this Suite's nested Suites.

    If the passed distributor is None, this trait's implementation of this method invokes run on each nested Suite in the List obtained by invoking nestedSuites. If a nested Suite's run method completes abruptly with an exception, this trait's implementation of this method reports that the Suite aborted and attempts to run the next nested Suite. If the passed distributor is defined, this trait's implementation puts each nested Suite into the Distributor contained in the Some, in the order in which the Suites appear in the List returned by nestedSuites, passing in a new Tracker obtained by invoking nextTracker on the Tracker passed to this method.

    Implementations of this method are responsible for ensuring SuiteStarting events are fired to the Reporter before executing any nested Suite, and either SuiteCompleted or SuiteAborted after executing any nested 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.

    Attributes
    protected
    Definition Classes
    SuiteAbstractSuite
  46. def runTest (testName: String, reporter: Reporter, stopper: Stopper, configMap: Map[String, Any], tracker: Tracker): Unit

    Run a test.

    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.)

    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.

    tracker

    a Tracker tracking Ordinals being fired by the current thread.

    Attributes
    protected
    Definition Classes
    FlatSpecSuiteAbstractSuite
  47. def runTests (testName: Option[String], reporter: Reporter, stopper: Stopper, filter: Filter, configMap: Map[String, Any], distributor: Option[Distributor], tracker: Tracker): Unit

    Run zero to many of this FlatSpec's tests.

    Run zero to many of this FlatSpec'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
    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.

    filter

    a Filter with which to filter tests based on their tags

    configMap

    a Map of key-value pairs that can be used by this Spec's executing 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.

    Attributes
    protected
    Definition Classes
    FlatSpecSuiteAbstractSuite
  48. implicit val shorthandSharedTestRegistrationFunction : (String) ⇒ BehaveWord

    Supports the shorthand form of shared test registration.

    Supports the shorthand form of shared test registration.

    For example, this method enables syntax such as the following in:

    "A Stack (with one item)" should behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
                              ^
    

    This function is passed as an implicit parameter to a should method provided in ShouldVerb, a must method provided in MustVerb, and a can method provided in CanVerb. When invoked, this function registers the subject description (the parameter to the function) and returns a BehaveWord.

    Attributes
    protected implicit
  49. implicit val shorthandTestRegistrationFunction : (String, String, String) ⇒ ResultOfStringPassedToVerb

    Supports the shorthand form of test registration.

    Supports the shorthand form of test registration.

    For example, this method enables syntax such as the following:

    "A Stack (when empty)" should "be empty" in { ... }
                           ^
    

    This function is passed as an implicit parameter to a should method provided in ShouldVerb, a must method provided in MustVerb, and a can method provided in CanVerb. When invoked, this function registers the subject description (the first parameter to the function) and returns a ResultOfStringPassedToVerb initialized with the verb and rest parameters (the second and third parameters to the function, respectively).

    Attributes
    protected implicit
  50. def suiteName : String

    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 Reports to pass to the suiteStarting, suiteCompleted, and suiteAborted methods of the Reporter.

    returns

    this Suite object's suite name.

    Definition Classes
    Suite
  51. def synchronized [T0] (arg0: ⇒ T0): T0

    Attributes
    final
    Definition Classes
    AnyRef
  52. def tags : Map[String, Set[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.

    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 FlatSpec 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.

    Definition Classes
    FlatSpecSuiteAbstractSuite
  53. def testNames : Set[String]

    An immutable Set of test names.

    An immutable Set of test names. If this FlatSpec contains no tests, this method returns an empty Set.

    This trait's implementation of this method will return a set that contains the names of all registered tests. The set's iterator will return those names in the order in which the tests were registered. Each test's name is composed of the concatenation of the text of each surrounding describer, in order from outside in, and the text of the example itself, with all components separated by a space. For example, consider this FlatSpec:

    import org.scalatest.FlatSpec
    
    class StackSpec extends FlatSpec {
    
      "A Stack (when not empty)" must "allow me to pop" in {}
      it must "not be empty" in {}
    
      "A Stack (when not full)" must "allow me to push" in {}
      it must "not be full" in {}
    }
    

    Invoking testNames on this Spec will yield a set that contains the following two test name strings:

    "A Stack (when not empty) must allow me to pop"
    "A Stack (when not empty) must not be empty"
    "A Stack (when not full) must allow me to push"
    "A Stack (when not full) must not be full"
    

    Definition Classes
    FlatSpecSuiteAbstractSuite
  54. def toString (): String

    Definition Classes
    AnyRef → Any
  55. def wait (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()
  56. def wait (arg0: Long, arg1: Int): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()
  57. def wait (arg0: Long): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()
  58. def withClue (clue: Any)(fun: ⇒ Unit): Unit

    Executes the block of code passed as the second parameter, and, if it completes abruptly with a ModifiableMessage exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it.

    Executes the block of code passed as the second parameter, and, if it completes abruptly with a ModifiableMessage exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it. If clue does not end in a white space character, one space will be added between it and the existing detail message (unless the detail message is not defined).

    This method allows you to add more information about what went wrong that will be reported when a test fails. Here's an example:

    withClue("(Employee's name was: " + employee.name + ")") {
      intercept[IllegalArgumentException] {
        employee.getTask(-1)
      }
    }
    

    If an invocation of intercept completed abruptly with an exception, the resulting message would be something like:

    (Employee's name was Bob Jones) Expected IllegalArgumentException to be thrown, but no exception was thrown
    

    Definition Classes
    Assertions
  59. def withFixture (test: NoArgTest): Unit

    Run the passed test function in the context of a fixture established by this method.

    Run the passed test function in the context of a fixture established by this method.

    This method should set up the fixture needed by the tests of the current suite, invoke the test function, and if needed, perform any clean up needed after the test completes. Because the NoArgTest function passed to this method takes no parameters, preparing the fixture will require side effects, such as reassigning instance vars in this Suite or initializing a globally accessible external database. If you want to avoid reassigning instance vars you can use FixtureSuite.

    This trait's implementation of runTest invokes this method for each test, passing in a NoArgTest whose apply method will execute the code of the test.

    This trait's implementation of this method simply invokes the passed NoArgTest function.

    test

    the no-arg test function to run with a fixture

    Attributes
    protected
    Definition Classes
    SuiteAbstractSuite

Inherited from CanVerb

Inherited from MustVerb

Inherited from ShouldVerb

Inherited from Suite

Inherited from AbstractSuite

Inherited from Assertions

Inherited from AnyRef

Inherited from Any