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org.scalatest.FeatureSpec.scala Maven / Gradle / Ivy

/*
 * Copyright 2001-2008 Artima, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.scalatest

import NodeFamily._
import scala.collection.immutable.ListSet
import org.scalatest.exceptions.StackDepthExceptionHelper.getStackDepthFun
import java.util.concurrent.atomic.AtomicReference
import java.util.ConcurrentModificationException
import org.scalatest.events._
import Suite.anErrorThatShouldCauseAnAbort

/**
 * 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 
 * 
 *
 * 

 * See also: Getting started with FeatureSpec.
 * 
 * 
 * 
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 ArithmeticSpec 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 ArithmeticSpec with:
 * 
 *
 * 
 * scala> (new ArithmeticSpec).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 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 ArithmeticSpec 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 ArithmeticSpec 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 ArithmeticSpec).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, 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 ArithmeticSpec 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 ArithmeticSpec with:
 * 
 *
 * 
 * scala> (new ArithmeticSpec).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 
 * 
 *
 * 
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.tags.SlowTest and
 * com.mycompany.tags.DbTest, then you could
 * create matching groups for FeatureSpecs like this:
 * 
 *
 * 
 * import org.scalatest.Tag
 *
 * object SlowTest extends Tag("com.mycompany.tags.SlowTest")
 * object DbTest extends Tag("com.mycompany.tags.DbTest")
 * 
 *
 * 

 * Given these definitions, you could place FeatureSpec tests into groups like this:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 *
 * class ArithmeticSpec 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.tags.SlowTest tag, 
 * and test "subtraction" with the com.mycompany.tags.DbTest tag.
 * 
 *
 * 

 * The run method takes a Filter, whose constructor takes an optional
 * Set[String] called tagsToInclude and a Set[String] called
 * tagsToExclude. If tagsToInclude is None, all tests will be run
 * except those those belonging to tags listed in the
 * tagsToExclude Set. If tagsToInclude is defined, only tests
 * belonging to tags mentioned in the tagsToInclude set, and not mentioned in tagsToExclude,
 * will be run.
 * 
 *
 * 
Shared fixtures
 *
 * 

 * A test fixture is objects or other artifacts (such as files, sockets, database
 * connections, etc.) used by tests to do their work.
 * If a fixture is used by only one test method, then the definitions of the fixture objects can
 * be local to the method, such as the objects assigned to sum and diff in the
 * previous ExampleSpec examples. If multiple methods need to share an immutable fixture, one approach
 * is to assign them to instance variables.
 * 
 *
 * 

 * In some cases, however, shared mutable fixture objects may be changed by test methods 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 3 offered 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 usually involves reassigning vars or mutating objects
 * between tests. Before going that route, you may wish to consider some more functional approaches that
 * avoid side effects.
 * 
 *
 * 
Calling create-fixture methods
 *
 * 

 * One approach is to write one or more create-fixture methods
 * that return a new instance of a needed fixture object (or an holder object containing multiple needed fixture objects) each time it
 * is called. You can then call a create-fixture method at the beginning of each
 * test method that needs the fixture, storing the returned object or objects in local variables. Here's an example:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import collection.mutable.ListBuffer
 *
 * class ExampleSpec extends FeatureSpec {
 * 
 *   def fixture =
 *     new {
 *       val builder = new StringBuilder("ScalaTest is ")
 *       val buffer = new ListBuffer[String]
 *     }
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       val f = fixture
 *       f.builder.append("easy!")
 *       assert(f.builder.toString === "ScalaTest is easy!")
 *       assert(f.buffer.isEmpty)
 *       f.buffer += "sweet"
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       val f = fixture
 *       f.builder.append("fun!")
 *       assert(f.builder.toString === "ScalaTest is fun!")
 *       assert(f.buffer.isEmpty)
 *     }
 *   }
 * }
 * 
 *
 * 

 * The “f.” in front of each use of a fixture object provides a visual indication of which objects 
 * are part of the fixture, but if you prefer, you can import the the members with “import f._” and use the names directly.
 * 
 *
 * 
Instantiating fixture traits
 *
 * 

 * A related technique is to place
 * the fixture objects in a fixture trait and run your test code in the context of a new anonymous class instance that mixes in
 * the fixture trait, like this:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSpec extends FeatureSpec {
 * 
 *   trait Fixture {
 *     val builder = new StringBuilder("ScalaTest is ")
 *     val buffer = new ListBuffer[String]
 *   }
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       new Fixture {
 *         builder.append("easy!")
 *         assert(builder.toString === "ScalaTest is easy!")
 *         assert(buffer.isEmpty)
 *         buffer += "sweet"
 *       }
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       new Fixture {
 *         builder.append("fun!")
 *         assert(builder.toString === "ScalaTest is fun!")
 *         assert(buffer.isEmpty)
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 
Mixing in OneInstancePerTest
 *
 * 

 * If every test method 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 Suite, similar to the way JUnit tests are executed. Here's an example:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import org.scalatest.OneInstancePerTest
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSpec extends FeatureSpec with OneInstancePerTest {
 * 
 *   val builder = new StringBuilder("ScalaTest is ")
 *   val buffer = new ListBuffer[String]
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *     }
 *   }
 * }
 * 
 *
 * 

 * Although the create-fixture, fixture-trait, 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, you'll need to either
 * use side effects or the loan pattern.
 * 
 *
 * 
Mixing in BeforeAndAfter
 *
 * 

 * One way to use side effects is to mix in the BeforeAndAfter trait.
 * With this trait you can denote a bit of code to run before each test with before and/or after each test
 * each test with after, like this:
 * 
 * 
 * 
 * import org.scalatest.FeatureSpec
 * import org.scalatest.BeforeAndAfter
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSpec extends FeatureSpec with BeforeAndAfter {
 * 
 *   val builder = new StringBuilder
 *   val buffer = new ListBuffer[String]
 * 
 *   before {
 *     builder.append("ScalaTest is ")
 *   }
 * 
 *   after {
 *     builder.clear()
 *     buffer.clear()
 *   }
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *     }
 *   }
 * }
 * 
 * 
 * 
Overriding withFixture(NoArgTest)
 *
 * 

 * An alternate way to take care of setup and cleanup via side effects
 * is to override withFixture. Trait Suite's implementation of
 * runTest, which is inherited by this trait, passes a no-arg test function to withFixture. It is withFixture's
 * responsibility to invoke that test function.  Suite's implementation of withFixture simply
 * invokes the function, like this:
 * 
 *
 * 
 * // Default implementation
 * protected def withFixture(test: NoArgTest) {
 *   test()
 * }
 * 
 *
 * 

 * You can, therefore, override withFixture to perform setup before, and cleanup after, invoking the test function. If
 * you have cleanup to perform, you should invoke the test function
 * inside a try block and perform the cleanup in a finally clause.
 * Here's an example:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import collection.mutable.ListBuffer
 *
 * class ExampleSpec extends FeatureSpec {
 *
 *   val builder = new StringBuilder
 *   val buffer = new ListBuffer[String]
 *
 *   override def withFixture(test: NoArgTest) {
 *     builder.append("ScalaTest is ") // perform setup
 *     try {
 *       test() // invoke the test function
 *     }
 *     finally {
 *       builder.clear() // perform cleanup
 *       buffer.clear()
 *     }
 *   }
 *
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 *
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *       buffer += "clear"
 *     }
 *   }
 * }
 * 
 *
 * 

 * Note that the NoArgTest passed to withFixture, in addition to
 * an apply method that executes the test, also includes the test name as well as the config
 * map passed to runTest. Thus you can also use the test name and configuration objects in withFixture.
 * 
 *
 * 

 * The reason you should perform cleanup in a finally clause is that withFixture is called by
 * runTest, which expects an exception to be thrown to indicate a failed test. Thus when you invoke
 * the test function inside withFixture, it may complete abruptly with an exception. The finally
 * clause will ensure the fixture cleanup happens as that exception propagates back up the call stack to runTest.
 * 
 *
 * 
Overriding withFixture(OneArgTest)
 *
 * 

 * To use the loan pattern, you can extend FeatureSpec (from the org.scalatest.fixture package) instead of
 * FeatureSpec. Each test in a FeatureSpec takes a fixture as a parameter, allowing you to pass the fixture into
 * the test. You must indicate the type of the fixture parameter by specifying FixtureParam, and implement a
 * withFixture method that takes a OneArgTest. This withFixture method is responsible for
 * invoking the one-arg test function, so you can perform fixture set up before, and clean up after, invoking and passing
 * the fixture into the test function. Here's an example:
 * 
 *
 * 
 * import org.scalatest.fixture
 * import java.io.FileWriter
 * import java.io.File
 * 
 * class ExampleSpec extends fixture.FeatureSpec {
 * 
 *   final val tmpFile = "temp.txt"
 * 
 *   type FixtureParam = FileWriter
 * 
 *   def withFixture(test: OneArgTest) {
 * 
 *     val writer = new FileWriter(tmpFile) // set up the fixture
 *     try {
 *       test(writer) // "loan" the fixture to the test
 *     }
 *     finally {
 *       writer.close() // clean up the fixture
 *     }
 *   }
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") { writer =>
 *       writer.write("Hello, test!")
 *       writer.flush()
 *       assert(new File(tmpFile).length === 12)
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") { writer =>
 *       writer.write("Hi, test!")
 *       writer.flush()
 *       assert(new File(tmpFile).length === 9)
 *     }
 *   }
 * }
 * 
 *
 * 

 * For more information, see the documentation for FeatureSpec.
 * 
 *
 * 
Providing different fixtures to different tests
 * 
 * 

 * If different tests in the same FeatureSpec require different fixtures, you can combine the previous techniques and
 * provide each test with just the fixture or fixtures it needs. Here's an example in which a StringBuilder and a
 * ListBuffer are provided via fixture traits, and file writer (that requires cleanup) is provided via the loan pattern:
 * 
 *
 * 
 * import java.io.FileWriter
 * import java.io.File
 * import collection.mutable.ListBuffer
 * import org.scalatest.FeatureSpec
 * 
 * class ExampleSpec extends FeatureSpec {
 * 
 *   final val tmpFile = "temp.txt"
 * 
 *   trait Builder {
 *     val builder = new StringBuilder("ScalaTest is ")
 *   }
 * 
 *   trait Buffer {
 *     val buffer = ListBuffer("ScalaTest", "is")
 *   }
 * 
 *   def withWriter(testCode: FileWriter => Any) {
 *     val writer = new FileWriter(tmpFile) // set up the fixture
 *     try {
 *       testCode(writer) // "loan" the fixture to the test
 *     }
 *     finally {
 *       writer.close() // clean up the fixture
 *     }
 *   }
 * 
 *   scenario("user is productive using the test framework") { // This test needs the StringBuilder fixture
 *     new Builder {
 *       builder.append("productive!")
 *       assert(builder.toString === "ScalaTest is productive!")
 *     }
 *   }
 * 
 *   scenario("tests are readable") { // This test needs the ListBuffer[String] fixture
 *     new Buffer {
 *       buffer += ("readable!")
 *       assert(buffer === List("ScalaTest", "is", "readable!"))
 *     }
 *   }
 * 
 *   scenario("the test framework is user-friendly") { // This test needs the FileWriter fixture
 *     withWriter { writer =>
 *       writer.write("Hello, user!")
 *       writer.flush()
 *       assert(new File(tmpFile).length === 12)
 *     }
 *   }
 * 
 *   scenario("test code is clear and concise") { // This test needs the StringBuilder and ListBuffer
 *     new Builder with Buffer {
 *       builder.append("clear!")
 *       buffer += ("concise!")
 *       assert(builder.toString === "ScalaTest is clear!")
 *       assert(buffer === List("ScalaTest", "is", "concise!"))
 *     }
 *   }
 * 
 *   scenario("user composes test artifacts") { // This test needs all three fixtures
 *     new Builder with Buffer {
 *       builder.append("clear!")
 *       buffer += ("concise!")
 *       assert(builder.toString === "ScalaTest is clear!")
 *       assert(buffer === List("ScalaTest", "is", "concise!"))
 *       withWriter { writer =>
 *         writer.write(builder.toString)
 *         writer.flush()
 *         assert(new File(tmpFile).length === 19)
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * In the previous example, "user is productive using the test framework uses only the StringBuilder fixture, so it just instantiates
 * a new Builder, whereas tests are readable uses only the ListBuffer fixture, so it just intantiates
 * a new Buffer. the test framework is user-friendly needs just the FileWriter fixture, so it invokes
 * withWriter, which prepares and passes a FileWriter to the test (and takes care of closing it afterwords).
 * 
 *
 * 

 * Two tests need multiple fixtures: test code is clear and concise needs both the StringBuilder and the
 * ListBuffer, so it instantiates a class that mixes in both fixture traits with new Builder with Buffer.
 * user composes test artifacts needs all three fixtures, so in addition to new Builder with Buffer it also invokes
 * withWriter, wrapping just the of the test code that needs the fixture.
 * 
 *
 * 

 * Note that in this case, the loan pattern is being implemented via the withWriter method that takes a function, not
 * by overriding FeatureSpec's withFixture(OneArgTest) method. FeatureSpec makes the most sense
 * if all (or at least most) tests need the same fixture, whereas in this Suite only two tests need the
 * FileWriter.
 * 
 *
 * 

 * In the previous example, the withWriter method passed an object into
 * the tests. Passing fixture objects into tests is generally a good idea when possible, but sometimes a side affect is unavoidable.
 * For example, if you need to initialize a database running on a server across a network, your with-fixture 
 * method will likely have nothing to pass. In such cases, simply create a with-fixture method that takes a by-name parameter and
 * performs setup and cleanup via side effects, like this:
 * 
 *
 * 
 * def withDataInDatabase(test: => Any) {
 *   // initialize the database across the network
 *   try {
 *     test // "loan" the initialized database to the test
 *   }
 *   finally {
 *     // clean up the database
 *   }
 * }
 * 
 * 
 * 

 * You can then use it like:
 * 
 * 
 * 
 * scenario("user logs in") {
 *   withDataInDatabase {
 *     // test user logging in scenario
 *   }
 * }
 * 
 * 
 * 
Composing stackable fixture traits
 *
 * 

 * In larger projects, teams often end up with several different fixtures that test classes need in different combinations,
 * and possibly initialized (and cleaned up) in different orders. A good way to accomplish this in ScalaTest is to factor the individual
 * fixtures into traits that can be composed using the stackable trait pattern. This can be done, for example, by placing
 * withFixture methods in several traits, each of which call super.withFixture. Here's an example in
 * which the StringBuilder and ListBuffer[String] fixtures used in the previous examples have been
 * factored out into two stackable fixture traits named Builder and Buffer:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import org.scalatest.AbstractSuite
 * import collection.mutable.ListBuffer
 * 
 * trait Builder extends AbstractSuite { this: Suite =>
 *
 *   val builder = new StringBuilder
 *
 *   abstract override def withFixture(test: NoArgTest) {
 *     builder.append("ScalaTest is ")
 *     try {
 *       super.withFixture(test) // To be stackable, must call super.withFixture
 *     }
 *     finally {
 *       builder.clear()
 *     }
 *   }
 * }
 *
 * trait Buffer extends AbstractSuite { this: Suite =>
 *
 *   val buffer = new ListBuffer[String]
 *
 *   abstract override def withFixture(test: NoArgTest) {
 *     try {
 *       super.withFixture(test) // To be stackable, must call super.withFixture
 *     }
 *     finally {
 *       buffer.clear()
 *     }
 *   }
 * }
 * 
 * class ExampleSpec extends FeatureSpec with Builder with Buffer {
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *       buffer += "clear"
 *     }
 *   }
 * }
 * 
 *
 * 

 * By mixing in both the Builder and Buffer traits, ExampleSpec gets both fixtures, which will be
 * initialized before each test and cleaned up after. The order the traits are mixed together determines the order of execution.
 * In this case, Builder is "super" to Buffer. If you wanted Buffer to be "super"
 * to Builder, you need only switch the order you mix them together, like this: 
 * 
 *
 * 
 * class Example2Spec extends FeatureSpec with Buffer with Builder
 * 
 *
 * 

 * And if you only need one fixture you mix in only that trait:
 * 
 *
 * 
 * class Example3Spec extends FeatureSpec with Builder
 * 
 *
 * 

 * Another way to create stackable fixture traits is by extending the BeforeAndAfterEach
 * and/or BeforeAndAfterAll traits.
 * BeforeAndAfterEach has a beforeEach method that will be run before each test (like JUnit's setUp),
 * and an afterEach method that will be run after (like JUnit's tearDown).
 * Similarly, BeforeAndAfterAll has a beforeAll method that will be run before all tests,
 * and an afterAll method that will be run after all tests. Here's what the previously shown example would look like if it
 * were rewritten to use the BeforeAndAfterEach methods instead of withFixture:
 * 
 *
 * 
 * import org.scalatest.FeatureSpec
 * import org.scalatest.BeforeAndAfterEach
 * import collection.mutable.ListBuffer
 * 
 * trait Builder extends BeforeAndAfterEach { this: Suite =>
 * 
 *   val builder = new StringBuilder
 * 
 *   override def beforeEach() {
 *     builder.append("ScalaTest is ")
 *     super.beforeEach() // To be stackable, must call super.beforeEach
 *   }
 * 
 *   override def afterEach() {
 *     try {
 *       super.afterEach() // To be stackable, must call super.afterEach
 *     }
 *     finally {
 *       builder.clear()
 *     }
 *   }
 * }
 * 
 * trait Buffer extends BeforeAndAfterEach { this: Suite =>
 * 
 *   val buffer = new ListBuffer[String]
 * 
 *   override def afterEach() {
 *     try {
 *       super.afterEach() // To be stackable, must call super.afterEach
 *     }
 *     finally {
 *       buffer.clear()
 *     }
 *   }
 * }
 * 
 * class ExampleSpec extends FeatureSpec with Builder with Buffer {
 * 
 *   feature("Fixtures can be shared") {
 * 
 *     scenario("user learns how to share fixtures") {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     scenario("user enjoys writing tests with shared fixtures") {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *       buffer += "clear"
 *     }
 *   }
 * }
 * 
 *
 * 

 * To get the same ordering as withFixture, place your super.beforeEach call at the end of each
 * beforeEach method, and the super.afterEach call at the beginning of each afterEach
 * method, as shown in the previous example. It is a good idea to invoke super.afterEach in a try
 * block and perform cleanup in a finally clause, as shown in the previous example, because this ensures the
 * cleanup code is performed even if super.afterAll throws an exception.
 * 
 *
 * 

 * One difference to bear in mind between the before-and-after traits and the withFixture methods, is that if
 * a withFixture method completes abruptly with an exception, it is considered a failed test. By contrast, if any of the
 * methods on the before-and-after traits (i.e., before  and after of BeforeAndAfter,
 * beforeEach and afterEach of BeforeAndAfterEach,
 * and beforeAll and afterAll of BeforeAndAfterAll) complete abruptly, it is considered a
 * failed suite, which will result in a SuiteAborted event.
 * 
 * 
 * 
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 val buf = new ListBuffer[T]
 *
 *   def push(o: T) {
 *     if (!full)
 *       buf.prepend(o)
 *     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 FunSpec'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:
 * 
 *
 * 

 * 
empty is invoked on this non-empty stack: Stack(9)
 * 
peek is invoked on this non-empty stack: Stack(9)
 * 
pop is invoked on this non-empty stack: Stack(9)
 * 
 *
 * 

 * Whereas calling it with the stackWithOneItemLessThanCapacity fixture, like this:
 * 
 *
 * 
 * scenariosFor(nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed))
 * 
 *
 * 

 * yields different test names:
 * 
 *
 * 

 * 
empty is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
 * 
peek is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
 * 
pop is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1)
 * 
 *
 * @author Bill Venners
 */
trait FeatureSpec extends Suite { thisSuite =>

  private final val engine = new Engine("concurrentFeatureSpecMod", "FeatureSpec")
  import engine._

  /**
   * 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.
   */
  implicit protected def info: Informer = atomicInformer.get

  /**
   * 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 FeatureSpec instance.
   *
   * @param specText the specification text, which will be combined with the descText of any surrounding describers
   * to form the test name
   * @param testTags the optional list of tags for this test
   * @param testFun the test function
   * @throws DuplicateTestNameException if a test with the same name has been registered previously
   * @throws TestRegistrationClosedException if invoked after run has been invoked on this suite
   * @throws NullPointerException if specText or any passed test tag is null
   */
  protected def scenario(specText: String, testTags: Tag*)(testFun: => Unit) {

    registerTest(Resources("scenario", specText), testFun _, "scenarioCannotAppearInsideAnotherScenario", "FeatureSpec.scala", "scenario", 2, None, None, testTags: _*)
  }

  /**
   * 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 FeatureSpec instance.
   *
   * @param specText the specification text, which will be combined with the descText of any surrounding describers
   * to form the test name
   * @param testTags the optional list of tags for this test
   * @param testFun the test function
   * @throws DuplicateTestNameException if a test with the same name has been registered previously
   * @throws TestRegistrationClosedException if invoked after run has been invoked on this suite
   * @throws NullPointerException if specText or any passed test tag is null
   */
  protected def ignore(specText: String, testTags: Tag*)(testFun: => Unit) {
    registerIgnoredTest(Resources("scenario", specText), testFun _, "ignoreCannotAppearInsideAScenario", "FeatureSpec.scala", "ignore", 1, testTags: _*)
  }
  
  /**
   * 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 feature(description: String)(fun: => Unit) {

    if (!currentBranchIsTrunk)
      throw new NotAllowedException(Resources("cantNestFeatureClauses"), getStackDepthFun("FeatureSpec.scala", "feature"))

    registerNestedBranch(description, None, fun, "featureCannotAppearInsideAScenario", "FeatureSpec.scala", "feature", 1)
  }

  /**
   * A Map whose keys are String tag names to which tests in this FeatureSpec 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. 
   * 
   */
  override def tags: Map[String, Set[String]] = atomic.get.tagsMap

  /**
   * 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.)
   *
   * @param testName the name of one test to execute.
   * @param reporter the Reporter to which results will be reported
   * @param stopper the Stopper that will be consulted to determine whether to stop execution early.
   * @param configMap a Map of properties that can be used by this FeatureSpec's executing tests.
   * @throws NullPointerException if any of testName, reporter, stopper, or configMap
   *     is null.
   */
  protected override def runTest(testName: String, reporter: Reporter, stopper: Stopper, configMap: Map[String, Any], tracker: Tracker) {

    def invokeWithFixture(theTest: TestLeaf) {
      val theConfigMap = configMap
      withFixture(
        new NoArgTest {
          def name = testName
          def apply() { theTest.testFun() }
          def configMap = theConfigMap
        }
      )
    }

    runTestImpl(thisSuite, testName, reporter, stopper, configMap, tracker, false, invokeWithFixture)
  }

  /**
   * 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
   * 
   *
   * @param 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.
   * @param reporter the Reporter to which results will be reported
   * @param stopper the Stopper that will be consulted to determine whether to stop execution early.
   * @param filter a Filter with which to filter tests based on their tags
   * @param configMap a Map of key-value pairs that can be used by the executing Suite of tests.
   * @param 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.
   * @param tracker a Tracker tracking Ordinals being fired by the current thread.
   * @throws NullPointerException if any of the passed parameters is null.
   * @throws IllegalArgumentException if testName is defined, but no test with the specified test name
   *     exists in this Suite
   */
  protected override def runTests(testName: Option[String], reporter: Reporter, stopper: Stopper, filter: Filter,
      configMap: Map[String, Any], distributor: Option[Distributor], tracker: Tracker) {
    
    runTestsImpl(thisSuite, testName, reporter, stopper, filter, configMap, distributor, tracker, info, false, runTest)
  }

  /**
   * 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 FeatureSpec 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"
   * 
   */
  // override def testNames: Set[String] = ListSet(atomic.get.testsList.map(_.testName): _*)
  override def testNames: Set[String] = {
    // I'm returning a ListSet here so that they tests will be run in registration order
    ListSet(atomic.get.testNamesList.toArray: _*)
  }

  override def run(testName: Option[String], reporter: Reporter, stopper: Stopper, filter: Filter,
      configMap: Map[String, Any], distributor: Option[Distributor], tracker: Tracker) {

    runImpl(thisSuite, testName, reporter, stopper, filter, configMap, distributor, tracker, super.run)
  }

  /**
   * 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.
   * 
   */
  protected def scenariosFor(unit: Unit) {}
  
  /**
   * Suite style name.
   */
  final override val styleName: String = "org.scalatest.FeatureSpec"
}