org.scalatest

trait FeatureSpec

[source: org/scalatest/FeatureSpec.scala]

trait FeatureSpec
extends Suite
A suite of tests in which each test represents one scenario of a feature. FeatureSpec is intended for writing tests that are "higher level" than unit tests, for example, integration tests, functional tests, and acceptance tests. You can use FeatureSpec for unit testing if you prefer, however. Here's an example:
 import org.scalatest.FeatureSpec
 import org.scalatest.GivenWhenThen
 import scala.collection.mutable.Stack
 
 class StackFeatureSpec extends FeatureSpec with GivenWhenThen {
 
   feature("The user can pop an element off the top of the stack") {
 
     info("As a programmer")
     info("I want to be able to pop items off the stack")
     info("So that I can get them in last-in-first-out order")
 
     scenario("pop is invoked on a non-empty stack") {
 
       given("a non-empty stack")
       val stack = new Stack[Int]
       stack.push(1)
       stack.push(2)
       val oldSize = stack.size
 
       when("when pop is invoked on the stack")
       val result = stack.pop()
 
       then("the most recently pushed element should be returned")
       assert(result === 2)
 
       and("the stack should have one less item than before")
       assert(stack.size === oldSize - 1)
     }
 
     scenario("pop is invoked on an empty stack") {
 
       given("an empty stack")
       val emptyStack = new Stack[String]
 
       when("when pop is invoked on the stack")
       then("NoSuchElementException should be thrown")
       intercept[NoSuchElementException] {
         emptyStack.pop()
       }
 
       and("the stack should still be empty")
       assert(emptyStack.isEmpty)
     }
   }
 }
 

A FeatureSpec contains feature clauses and scenarios. You define a feature clause with feature, and a scenario with scenario. Both feature and scenario are methods, defined in FeatureSpec, which will be invoked by the primary constructor of StackFeatureSpec. A feature clause describes a feature of the subject (class or other entity) you are specifying and testing. In the previous example, the subject under specification and test is a stack. The feature being specified and tested is the ability for a user (a programmer in this case) to pop an element off the top of the stack. With each scenario you provide a string (the spec text) that specifies the behavior of the subject for one scenario in which the feature may be used, and a block of code that tests that behavior. You place the spec text between the parentheses, followed by the test code between curly braces. The test code will be wrapped up as a function passed as a by-name parameter to scenario, which will register the test for later execution.

A FeatureSpec'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.

Scenarios can only be registered with the scenario method while the FeatureSpec is in its registration phase. Any attempt to register a scenario after the FeatureSpec has entered its ready phase, i.e., after run has been invoked on the FeatureSpec, will be met with a thrown TestRegistrationClosedException. The recommended style of using FeatureSpec 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.

Each scenario represents one test. The name of the test is the spec text passed to the scenario method. The feature name does not appear as part of the test name. In a FeatureSpec, therefore, you must take care to ensure that each test has a unique name (in other words, that each scenario has unique spec text).

When you run a FeatureSpec, it will send Formatters in the events it sends to the Reporter. ScalaTest's built-in reporters will report these events in such a way that the output is easy to read as an informal specification of the subject being tested. For example, if you ran StackFeatureSpec from within the Scala interpreter:

 scala> (new StackFeatureSpec).execute()
 

You would see:

 Feature: The user can pop an element off the top of the stack 
   As a programmer 
   I want to be able to pop items off the stack 
   So that I can get them in last-in-first-out order 
   Scenario: pop is invoked on a non-empty stack
     Given a non-empty stack 
     When when pop is invoked on the stack 
     Then the most recently pushed element should be returned 
     And the stack should have one less item than before 
   Scenario: pop is invoked on an empty stack
     Given an empty stack 
     When when pop is invoked on the stack 
     Then NoSuchElementException should be thrown 
     And the stack should still be empty 
 

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 FeatureSpecs 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 FeatureSpec.

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 StackFeatureSpec examples. If multiple tests need to share a fixture, the best 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.FeatureSpec

 class ArithmeticFeatureSpec extends FeatureSpec {

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

   feature("Integer arithmetic") {

     scenario("addition") {
       val sum = 2 + 3
       assert(sum === shared)
     }

     scenario("subtraction") {
       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.FeatureSpec
 import scala.collection.mutable.ListBuffer

 class MyFeatureSpec extends FeatureSpec {

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

   feature("The create-fixture approach") {

     scenario("shared fixture objects are mutated by a test") {
       val (builder, lbuf) = createFixture
       builder.append("easy!")
       assert(builder.toString === "ScalaTest is easy!")
       assert(lbuf.isEmpty)
       lbuf += "sweet"
     }

     scenario("test gets a fresh copy of the shared fixture") {
       val (builder, lbuf) = createFixture
       builder.append("fun!")
       assert(builder.toString === "ScalaTest is fun!")
       assert(lbuf.isEmpty)
     }
   }
 }
 

If different tests in the same FeatureSpec 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 FeatureSpec, 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.FeatureSpec
 import org.scalatest.BeforeAndAfterEach
 import java.io.FileReader
 import java.io.FileWriter
 import java.io.File

 class FileIoFeatureSpec extends FeatureSpec 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()
   }

   feature("Reading and writing files") {

     scenario("reading from a temp file") {
       var builder = new StringBuilder
       var c = reader.read()
       while (c != -1) {
         builder.append(c.toChar)
         c = reader.read()
       }
       assert(builder.toString === "Hello, test!")
     }

     scenario("reading first char of a temp file") {
       assert(reader.read() === 'H')
     }
 
     scenario("no fixture is passed") { 
       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.FeatureSpec
 import org.scalatest.BeforeAndAfterEach
 import java.io.FileReader
 import java.io.FileWriter
 import java.io.File

 class FileIoFeatureSpec extends FeatureSpec {

   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()
     }
   }

   feature("Reading and writing files") {

     scenario("reading from a temp file") {
       var builder = new StringBuilder
       var c = reader.read()
       while (c != -1) {
         builder.append(c.toChar)
         c = reader.read()
       }
       assert(builder.toString === "Hello, test!")
     }

     scenario("reading first char of a temp file") {
       assert(reader.read() === 'H')
     }
 
     scenario("no fixture is passed") { 
       assert(1 + 1 === 2)
     }
   }
 }
 

If you prefer to keep your test classes immutable, one final variation is to use the FixtureFeatureSpec trait from the org.scalatest.fixture package. Tests in an org.scalatest.fixture.FixtureFeatureSpec 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 FixtureFeatureSpec 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 FixtureFeatureSpec 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 FixtureFeatureSpec, like this:

 import org.scalatest.fixture.FixtureFeatureSpec
 import java.io.FileReader
 import java.io.FileWriter
 import java.io.File
 
 class MySuite extends FixtureFeatureSpec {

   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()
     }
   }
 
   feature("Reading and writing files") {

     scenario("reading from a temp file") { reader =>
       var builder = new StringBuilder
       var c = reader.read()
       while (c != -1) {
         builder.append(c.toChar)
         c = reader.read()
       }
       assert(builder.toString === "Hello, test!")
     }
 
     scenario("reading first char of a temp file") { reader =>
       assert(reader.read() === 'H')
     }
 
     scenario("no fixture is passed") { () =>
       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 FixtureFeatureSpec approach shown previously is that two of the FixtureFeatureSpec'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 "no fixture passed" scenario, a FixtureFeatureSpec 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 FixtureFeatureSpec 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 FeatureSpec, you can use MultipleFixtureFeatureSpec.)

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 scenarios

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 FeatureSpec, you first place shared tests (i.e., shared scenarios) in behavior functions. These behavior functions will be invoked during the construction phase of any FeatureSpec that uses them, so that the scenarios they contain will be registered as scenarios in that FeatureSpec. 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 scenarios that make sense any time the stack is non-empty. Thus you'd ideally want to run those same scenarios 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 scenarios out into a behavior function, into which you pass the stack fixture to use when running the tests. So in your FeatureSpec for stack, you'd invoke the behavior function three times, passing in each of the three stack fixtures so that the shared scenarios are run for all three fixtures.

You can define a behavior function that encapsulates these shared scenarios inside the FeatureSpec that uses them. If they are shared between different FeatureSpecs, however, you could also define them in a separate trait that is mixed into each FeatureSpec 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 scenarios for non-full stacks:

 import org.scalatest.FeatureSpec
 import org.scalatest.GivenWhenThen
 import org.scalatestexamples.helpers.Stack
 
 trait FeatureSpecStackBehaviors { this: FeatureSpec with GivenWhenThen =>
 
   def nonEmptyStack(createNonEmptyStack: => Stack[Int], lastItemAdded: Int) {
 
     scenario("empty is invoked on this non-empty stack: " + createNonEmptyStack.toString) {
 
       given("a non-empty stack")
       val stack = createNonEmptyStack
 
       when("empty is invoked on the stack")
       then("empty returns false")
       assert(!stack.empty)
     }
 
     scenario("peek is invoked on this non-empty stack: " + createNonEmptyStack.toString) {
 
       given("a non-empty stack")
       val stack = createNonEmptyStack
       val size = stack.size
 
       when("peek is invoked on the stack")
       then("peek returns the last item added")
       assert(stack.peek === lastItemAdded)
 
       and("the size of the stack is the same as before")
       assert(stack.size === size)
     }
 
     scenario("pop is invoked on this non-empty stack: " + createNonEmptyStack.toString) {
 
       given("a non-empty stack")
       val stack = createNonEmptyStack
       val size = stack.size
 
       when("pop is invoked on the stack")
       then("pop returns the last item added")
       assert(stack.pop === lastItemAdded)
 
       and("the size of the stack one less than before")
       assert(stack.size === size - 1)
     }
   }
   
   def nonFullStack(createNonFullStack: => Stack[Int]) {
       
     scenario("full is invoked on this non-full stack: " + createNonFullStack.toString) {
 
       given("a non-full stack")
       val stack = createNonFullStack
 
       when("full is invoked on the stack")
       then("full returns false")
       assert(!stack.full)
     }
       
     scenario("push is invoked on this non-full stack: " + createNonFullStack.toString) {
 
       given("a non-full stack")
       val stack = createNonFullStack
       val size = stack.size
 
       when("push is invoked on the stack")
       stack.push(7)
 
       then("the size of the stack is one greater than before")
       assert(stack.size === size + 1)
 
       and("the top of the stack contains the pushed value")
       assert(stack.peek === 7)
     }
   }
 }
 

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

 scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed))
 scenariosFor(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:

 scenariosFor(nonEmptyStack) // assuming lastValuePushed is also in scope inside nonEmptyStack
 scenariosFor(nonFullStack)
 

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

 import org.scalatest.FeatureSpec
 import org.scalatest.GivenWhenThen
 import org.scalatestexamples.helpers.Stack
 
 class StackFeatureSpec extends FeatureSpec with GivenWhenThen with FeatureSpecStackBehaviors {
 
   // 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
  
   feature("A Stack is pushed and popped") {
  
     scenario("empty is invoked on an empty stack") {
 
       given("an empty stack")
       val stack = emptyStack
 
       when("empty is invoked on the stack")
       then("empty returns true")
       assert(stack.empty)
     }
  
     scenario("peek is invoked on an empty stack") {
 
       given("an empty stack")
       val stack = emptyStack
 
       when("peek is invoked on the stack")
       then("peek throws IllegalStateException")
       intercept[IllegalStateException] {
         stack.peek
       }
     }
  
     scenario("pop is invoked on an empty stack") {
 
       given("an empty stack")
       val stack = emptyStack
 
       when("pop is invoked on the stack")
       then("pop throws IllegalStateException")
       intercept[IllegalStateException] {
         emptyStack.pop
       }
     }
  
     scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed))
     scenariosFor(nonFullStack(stackWithOneItem))
  
     scenariosFor(nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed))
     scenariosFor(nonFullStack(stackWithOneItemLessThanCapacity))
  
     scenario("full is invoked on a full stack") {
 
       given("an full stack")
       val stack = fullStack
 
       when("full is invoked on the stack")
       then("full returns true")
       assert(stack.full)
     }
  
     scenariosFor(nonEmptyStack(fullStack, lastValuePushed))
  
     scenario("push is invoked on a full stack") {
 
       given("an full stack")
       val stack = fullStack
 
       when("push is invoked on the stack")
       then("push throws IllegalStateException")
       intercept[IllegalStateException] {
         stack.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 StackFeatureSpec).execute()
 Feature: A Stack is pushed and popped 
   Scenario: empty is invoked on an empty stack
     Given an empty stack 
     When empty is invoked on the stack 
     Then empty returns true 
   Scenario: peek is invoked on an empty stack
     Given an empty stack 
     When peek is invoked on the stack 
     Then peek throws IllegalStateException 
   Scenario: pop is invoked on an empty stack
     Given an empty stack 
     When pop is invoked on the stack 
     Then pop throws IllegalStateException 
   Scenario: empty is invoked on this non-empty stack: Stack(9)
     Given a non-empty stack 
     When empty is invoked on the stack 
     Then empty returns false 
   Scenario: peek is invoked on this non-empty stack: Stack(9)
     Given a non-empty stack 
     When peek is invoked on the stack 
     Then peek returns the last item added 
     And the size of the stack is the same as before 
   Scenario: pop is invoked on this non-empty stack: Stack(9)
     Given a non-empty stack 
     When pop is invoked on the stack 
     Then pop returns the last item added 
     And the size of the stack one less than before 
   Scenario: full is invoked on this non-full stack: Stack(9)
     Given a non-full stack 
     When full is invoked on the stack 
     Then full returns false 
   Scenario: push is invoked on this non-full stack: Stack(9)
     Given a non-full stack 
     When push is invoked on the stack 
     Then the size of the stack is one greater than before 
     And the top of the stack contains the pushed value 
   Scenario: empty is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
     Given a non-empty stack 
     When empty is invoked on the stack 
     Then empty returns false 
   Scenario: peek is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
     Given a non-empty stack 
     When peek is invoked on the stack 
     Then peek returns the last item added 
     And the size of the stack is the same as before 
   Scenario: pop is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
     Given a non-empty stack 
     When pop is invoked on the stack 
     Then pop returns the last item added 
     And the size of the stack one less than before 
   Scenario: full is invoked on this non-full stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
     Given a non-full stack 
     When full is invoked on the stack 
     Then full returns false 
   Scenario: push is invoked on this non-full stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
     Given a non-full stack 
     When push is invoked on the stack 
     Then the size of the stack is one greater than before 
     And the top of the stack contains the pushed value 
   Scenario: full is invoked on a full stack
     Given an full stack 
     When full is invoked on the stack 
     Then full returns true 
   Scenario: empty is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
     Given a non-empty stack 
     When empty is invoked on the stack 
     Then empty returns false 
   Scenario: peek is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
     Given a non-empty stack 
     When peek is invoked on the stack 
     Then peek returns the last item added 
     And the size of the stack is the same as before 
   Scenario: pop is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
     Given a non-empty stack 
     When pop is invoked on the stack 
     Then pop returns the last item added 
     And the size of the stack one less than before 
   Scenario: push is invoked on a full stack
     Given an full stack 
     When push is invoked on the stack 
     Then push throws IllegalStateException 
 

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. In a FeatureSpec there is no nesting construct analogous to Spec's describe clause. Therefore, you need to do a bit of extra work to ensure that the test names are unique. If a duplicate test name problem shows up in a FeatureSpec, you'll need to pass in a prefix or suffix string to add to each test name. You can pass this string the same way you pass any other data needed by the shared tests, or just call toString on the shared fixture object. This is the approach taken by the previous FeatureSpecStackBehaviors example.

Given this FeatureSpecStackBehaviors trait, calling it with the stackWithOneItem fixture, like this:

 scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed))
 

yields test names:

Whereas calling it with the stackWithOneItemLessThanCapacity fixture, like this:

 scenariosFor(nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed))
 

yields different test names:

Tagging tests

A FeatureSpec's tests may be classified into groups by tagging them with string names. As with any suite, when executing a FeatureSpec, groups of tests can optionally be included and/or excluded. To tag a FeatureSpec's tests, you pass objects that extend abstract class org.scalatest.Tag to methods that register tests, test and ignore. 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 FeatureSpecs 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 FeatureSpecs 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 FeatureSpec tests into groups like this:

 import org.scalatest.FeatureSpec

 class ArithmeticFeatureSpec extends FeatureSpec {

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

   feature("Integer arithmetic") {

     scenario("addition", SlowTest) {
       val sum = 2 + 3
       assert(sum === shared)
     }

     scenario("subtraction", SlowTest, DbTest) {
       val diff = 7 - 2
       assert(diff === shared)
     }
   }
 }
 

This code marks both tests, "addition" and "subtraction," with the com.mycompany.groups.SlowTest tag, and test "subtraction" 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, FeatureSpec provides registration methods that start with ignore instead of scenario. For example, to temporarily disable the test named addition, just change “scenario” into “ignore,” like this:

 import org.scalatest.FeatureSpec

 class ArithmeticFeatureSpec extends FeatureSpec {

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

   feature("Integer arithmetic") {

     ignore("addition") {
       val sum = 2 + 3
       assert(sum === shared)
     }

     scenario("subtraction") {
       val diff = 7 - 2
       assert(diff === shared)
     }
   }
 }
 

If you run this version of ArithmeticFeatureSpec with:

 scala> (new ArithmeticFeatureSpec).execute()
 

It will run only subtraction and report that addition was ignored:

 Feature: Integer arithmetic 
   Scenario: addition !!! IGNORED !!!
   Scenario: subtraction
 

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 FeatureSpec'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.FeatureSpec

 class ArithmeticFeatureSpec extends FeatureSpec {

   feature("Integer arithmetic") {

     scenario("addition") {
       val sum = 2 + 3
       assert(sum === 5)
       info("Addition seems to work")
     }

     scenario("subtraction") {
       val diff = 7 - 2
       assert(diff === 5)
     }
   }
 }
 
If you run this ArithmeticFeatureSpec from the interpreter, you will see the following message included in the printed report:
 Feature: Integer arithmetic 
   Scenario: addition
     Addition seems to work 
 

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

 import org.scalatest.FeatureSpec
 import org.scalatest.GivenWhenThen
 
 class ArithmeticSpec extends FeatureSpec with GivenWhenThen {
 
   feature("Integer arithmetic") {

     scenario("addition") {
 
       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)
     }

     scenario("subtraction") {
 
       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)
     }
   }
 }
 

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

 scala> (new ArithmeticFeatureSpec).execute()
 Feature: Integer arithmetic 
   Scenario: addition
     Given two integers 
     When they are added 
     Then the result is the sum of the two numbers 
   Scenario: subtraction
     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, has not yet been implemented. You can mark tests as pending in a FeatureSpec like this:

 import org.scalatest.FeatureSpec

 class ArithmeticFeatureSpec extends FeatureSpec {

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

   feature("Integer arithmetic") {

     scenario("addition") {
       val sum = 2 + 3
       assert(sum === shared)
     }

     scenario("subtraction") (pending)
   }
 }
 

(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 ArithmeticFeatureSpec with:

 scala> (new ArithmeticFeatureSpec).execute()
 

It will run both tests, but report that subtraction is pending. You'll see:

 Feature: Integer arithmetic 
   Scenario: addition
   Scenario: subtraction (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 FeatureSpec:

   feature("Integer arithmetic") {

     scenario("addition") {
       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:

 Feature: Integer arithmetic 
   Scenario: addition (pending)
     Given two integers 
     When they are added 
     Then the result is the sum of the two numbers 
 
Author
Bill Venners
Method Summary
protected def feature (description : java.lang.String)(f : => Unit) : Unit
Describe a “subject” being specified and tested by the passed function value. The passed function value may contain more describers (defined with describe) and/or tests (defined with it). This trait's implementation of this method will register the description string and immediately invoke the passed function.
protected def ignore (specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
Register a test to ignore, which has the given spec text, optional tags, and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected def ignore (specText : java.lang.String)(testFun : => Unit) : Unit
Register a test to ignore, which has the given spec text and test function value that takes no arguments. This method will register the test for later ignoring via an invocation of one of the execute methods. This method exists to make it easy to ignore an existing test by changing the call to it to ignore without deleting or commenting out the actual test code. The test will not be executed, but a report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected implicit def info : Informer
Returns an Informer that during test execution will forward strings (and other objects) passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked while this FeatureSpec is being executed, such as from inside a test function, it will forward the information to the current reporter immediately. If invoked at any other time, it will throw an exception. This method can be called safely by any thread.
override def run (testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Runs this suite of tests.
protected override def runTest (testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
Run a test. This trait's implementation runs the test registered with the name specified by testName. Each test's name is a concatenation of the text of all describers surrounding a test, from outside in, and the test's spec text, with one space placed between each item. (See the documenation for testNames for an example.)
protected override def runTests (testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Run zero to many of this FeatureSpec's tests.
protected def scenario (specText : java.lang.String)(testFun : => Unit) : Unit
Register a test with the given spec text and test function value that takes no arguments. This method will register the test for later execution via an invocation of one of the execute methods. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected def scenario (specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
Register a test with the given spec text, optional tags, and test function value that takes no arguments. An invocation of this method is called an “example.” This method will register the test for later execution via an invocation of one of the execute methods. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
protected def scenariosFor (unit : Unit) : Unit
Registers shared scenarios.
override def tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A Map whose keys are String tag names to which tests in this Spec belong, and values the Set of test names that belong to each tag. If this FeatureSpec contains no tags, this method returns an empty Map.
override def testNames : scala.collection.immutable.Set[java.lang.String]
An immutable Set of test names. If this FeatureSpec contains no tests, this method returns an empty Set.
Methods inherited from Suite
nestedSuites, execute, execute, execute, execute, groups, withFixture, runNestedSuites, suiteName, pending, pendingUntilFixed, expectedTestCount
Methods inherited from Assertions
assert, assert, assert, assert, convertToEqualizer, intercept, expect, expect, fail, fail, fail, fail
Methods inherited from AnyRef
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Method Details
protected implicit def info : Informer
Returns an Informer that during test execution will forward strings (and other objects) passed to its apply method to the current reporter. If invoked in a constructor, it will register the passed string for forwarding later during test execution. If invoked while this FeatureSpec is being executed, such as from inside a test function, it will forward the information to the current reporter immediately. If invoked at any other time, it will throw an exception. This method can be called safely by any thread.

protected def scenario(specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
Register a test with the given spec text, optional tags, and test function value that takes no arguments. An invocation of this method is called an “example.” This method will register the test for later execution via an invocation of one of the execute methods. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
Parameters
specText - the specification text, which will be combined with the descText of any surrounding describers to form the test name
testTags - the optional list of tags for this test
testFun - the test function
Throws
DuplicateTestNameException - if a test with the same name has been registered previously
TestRegistrationClosedException - if invoked after run has been invoked on this suite
NullPointerException - if specText or any passed test tag is null

protected def scenario(specText : java.lang.String)(testFun : => Unit) : Unit
Register a test with the given spec text and test function value that takes no arguments. This method will register the test for later execution via an invocation of one of the execute methods. The name of the test will be a concatenation of the text of all surrounding describers, from outside in, and the passed spec text, with one space placed between each item. (See the documenation for testNames for an example.) The resulting test name must not have been registered previously on this Spec instance.
Parameters
specText - the specification text, which will be combined with the descText of any surrounding describers to form the test name
testFun - the test function
Throws
DuplicateTestNameException - if a test with the same name has been registered previously
TestRegistrationClosedException - if invoked after run has been invoked on this suite
NullPointerException - if specText or any passed test tag is null

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

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

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

override def tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A Map whose keys are String tag names to which tests in this Spec belong, and values the Set of test names that belong to each tag. If this FeatureSpec contains no tags, this method returns an empty Map.

This trait's implementation returns tags that were passed as strings contained in Tag objects passed to methods test and ignore.

Overrides
Suite.tags

protected override def runTest(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
Run a test. This trait's implementation runs the test registered with the name specified by testName. Each test's name is a concatenation of the text of all describers surrounding a test, from outside in, and the test's spec text, with one space placed between each item. (See the documenation for testNames for an example.)
Parameters
testName - the name of one test to execute.
reporter - the Reporter to which results will be reported
stopper - the Stopper that will be consulted to determine whether to stop execution early.
configMap - a Map of properties that can be used by this Spec's executing tests.
Throws
NullPointerException - if any of testName, reporter, stopper, or configMap is null.
Overrides
Suite.runTest

protected override def runTests(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Run zero to many of this FeatureSpec's tests.

This method takes a testName parameter that optionally specifies a test to invoke. If testName is Some, this trait's implementation of this method invokes runTest on this object, passing in:

  • testName - the String value of the testName Option passed to this method
  • reporter - the Reporter passed to this method, or one that wraps and delegates to it
  • stopper - the Stopper passed to this method, or one that wraps and delegates to it
  • configMap - the configMap passed to this method, or one that wraps and delegates to it

This method takes a Set of tag names that should be included (tagsToInclude), and a Set that should be excluded (tagsToExclude), when deciding which of this Suite's tests to execute. If tagsToInclude is empty, all tests will be executed except those those belonging to tags listed in the tagsToExclude Set. If tagsToInclude is non-empty, only tests belonging to tags mentioned in tagsToInclude, and not mentioned in tagsToExclude will be executed. However, if testName is Some, tagsToInclude and tagsToExclude are essentially ignored. Only if testName is None will tagsToInclude and tagsToExclude be consulted to determine which of the tests named in the testNames Set should be run. For more information on trait tags, see the main documentation for this trait.

If testName is None, this trait's implementation of this method invokes testNames on this Suite to get a Set of names of tests to potentially execute. (A testNames value of None essentially acts as a wildcard that means all tests in this Suite that are selected by tagsToInclude and tagsToExclude should be executed.) For each test in the testName Set, in the order they appear in the iterator obtained by invoking the elements method on the Set, this trait's implementation of this method checks whether the test should be run based on the tagsToInclude and tagsToExclude Sets. If so, this implementation invokes runTest, passing in:

  • testName - the String name of the test to run (which will be one of the names in the testNames Set)
  • reporter - the Reporter passed to this method, or one that wraps and delegates to it
  • stopper - the Stopper passed to this method, or one that wraps and delegates to it
  • configMap - the configMap passed to this method, or one that wraps and delegates to it
Parameters
testName - an optional name of one test to run. If None, all relevant tests should be run. I.e., None acts like a wildcard that means run all relevant tests in this Suite.
reporter - the Reporter to which results will be reported
stopper - the Stopper that will be consulted to determine whether to stop execution early.
filter - a Filter with which to filter tests based on their tags
configMap - a Map of key-value pairs that can be used by the executing Suite of tests.
distributor - an optional Distributor, into which to put nested Suites to be run by another entity, such as concurrently by a pool of threads. If None, nested Suites will be run sequentially.
tracker - a Tracker tracking Ordinals being fired by the current thread.
Throws
NullPointerException - if any of the passed parameters is null.
IllegalArgumentException - if testName is defined, but no test with the specified test name exists in this Suite
Overrides
Suite.runTests

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

   import org.scalatest.FeatureSpec
  
   class StackSpec extends FeatureSpec {
     feature("A Stack") {
       scenario("(when not empty) must allow me to pop") {}
       scenario("(when not full) must allow me to push") {}
     }
   }
   

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 full) must allow me to push"
   
Overrides
Suite.testNames

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

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

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

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

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

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

protected def scenariosFor(unit : Unit) : Unit
Registers shared scenarios.

This method enables the following syntax for shared scenarios in a FeatureSpec:

   scenariosFor(nonEmptyStack(lastValuePushed))
   

This method just provides syntax sugar intended to make the intent of the code clearer. Because the parameter passed to it is type Unit, the expression will be evaluated before being passed, which is sufficient to register the shared scenarios. For examples of shared scenarios, see the Shared scenarios section in the main documentation for this trait.



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