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/*
 * 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 verb.{CanVerb, ResultOfAfterWordApplication, ShouldVerb, BehaveWord,
  MustVerb, StringVerbBlockRegistration}
import NodeFamily._
import scala.collection.immutable.ListSet
import org.scalatest.exceptions.StackDepthExceptionHelper.getStackDepth
import java.util.concurrent.atomic.AtomicReference
import java.util.ConcurrentModificationException
import org.scalatest.events._
import Suite.anErrorThatShouldCauseAnAbort
import Suite.autoTagClassAnnotations

/**
 * Trait that facilitates a “behavior-driven” style of development (BDD), in which tests
 * are nested inside text clauses denoted with the dash operator (-).
 *
 * 

 * Trait FreeSpec is so named because unlike traits such as WordSpec, FlatSpec, and FunSpec,
 * it is enforces no structure on the text. You are free to compose text however you like. (A FreeSpec is like free-verse poetry as
 * opposed to a sonnet or haiku, which defines a structure for the text of the poem.)
 * 
 * 
 * 

 * Recommended Usage:
 * Because it gives absolute freedom (and no guidance) on how specification text should be written, FreeSpec is a good choice for teams experienced 
 * with BDD and able to agree on how to structure the specification text.
 * 
 * 
 * 

 * Here's an example FreeSpec:
 * 
 *
 * 
 * package org.scalatest.examples.freespec
 * 
 * import org.scalatest.FreeSpec
 * 
 * class SetSpec extends FreeSpec {
 * 
 *   "A Set" - {
 *     "when empty" - {
 *       "should have size 0" in {
 *         assert(Set.empty.size === 0)
 *       }
 *       
 *       "should produce NoSuchElementException when head is invoked" in {
 *         intercept[NoSuchElementException] {
 *           Set.empty.head
 *         }
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * In a FreeSpec you write a test with a string followed by in and the body of the
 * test in curly braces, like this:
 * 
 * 
 * 
 * "should have size 0" in {
 *   // ...
 * }
 * 
 * 
 * 

 * You can nest a test inside any number of description clauses, which you write with a string followed by a dash character
 * and a block, like this:  
 * 
 *
 * 
 * "A Set" - {
 *   // ...
 * }
 * 
 * 
 * 

 * You can nest description clauses as deeply as you want. Because the description clause is denoted with an operator, not
 * a word like should, you are free to structure the text however you wish. Here's an example:
 * 
 *
 * 
 * import org.scalatest.FreeSpec
 * 
 * class StackSpec extends FreeSpec {
 *   "A Stack" - {
 *     "whenever it is empty" - {
 *       "certainly ought to" - {
 *         "be empty" in {
 *           // ...
 *         }
 *         "complain on peek" in {
 *           // ...
 *         }
 *         "complain on pop" in {
 *           // ...
 *         }
 *       }
 *     }
 *     "but when full, by contrast, must" - {
 *       "be full" in {
 *         // ...
 *       }
 *       "complain on push" in {
 *         // ...
 *       }
 *     }
 *   }
 * }
 * 
 * 
 * 

 * Running the above StackSpec in the interpreter would yield:
 * 
 * 
 * 
 * scala> new StackSpec execute
 * StackSpec:
 * A Stack 
 *   whenever it is empty 
 *     certainly ought to 
 *     - be empty
 *     - complain on peek
 *     - complain on pop
 *   but when full, by contrast, must 
 *   - be full
 *   - complain on push
 * 
 *
 * 

 * A FreeSpec can also be used to write a specification-style test in languages other than English. For
 * example:
 * 
 *
 * 
 * import org.scalatest.FreeSpec
 *
 * class ComputerRoomRulesSpec extends FreeSpec {
 *   "Achtung!" - {
 *     "Alle touristen und non-technischen lookenpeepers!" - {
 *       "Das machine is nicht fuer fingerpoken und mittengrabben." in {
 *         // ...
 *       }
 *       "Is easy" - {
 *         "schnappen der springenwerk" in {
 *           // ...
 *         }
 *         "blowenfusen" in {
 *           // ...
 *         }
 *         "und poppencorken mit spitzen sparken." in {
 *           // ...
 *         }
 *       }
 *       "Das machine is diggen by experten only." in {
 *         // ...
 *       }
 *       "Is nicht fuer gerwerken by das dummkopfen." in {
 *         // ...
 *       }
 *       "Das rubbernecken sightseeren keepen das cottenpicken hands in das pockets." in {
 *         // ...
 *       }
 *       "Relaxen und watchen das blinkenlights." in {
 *         // ...
 *       }
 *     }
 *   }
 * }
 * 
 * 
 * 

 * Running the above ComputerRoomRulesSpec in the interpreter would yield:
 * 
 * 
 * 
 * scala> new ComputerRoomRulesSpec execute
 * ComputerRoomRulesSpec:
 * Achtung! 
 *   Alle touristen und non-technischen lookenpeepers! 
 *   - Das machine is nicht fuer fingerpoken und mittengrabben.
 *     Is easy 
 *     - schnappen der springenwerk
 *     - blowenfusen
 *     - und poppencorken mit spitzen sparken.
 *   - Das machine is diggen by experten only.
 *   - Is nicht fuer gerwerken by das dummkopfen.
 *   - Das rubbernecken sightseeren keepen das cottenpicken hands in das pockets.
 *   - Relaxen und watchen das blinkenlights.
 * 
 *
 * 

 * A FreeSpec's lifecycle has two phases: the registration phase and the
 * ready phase. It starts in registration phase and enters ready phase the first time
 * run is called on it. It then remains in ready phase for the remainder of its lifetime.
 * 
 *
 * 

 * Tests can only be registered while the FreeSpec is
 * in its registration phase. Any attempt to register a test after the FreeSpec has
 * entered its ready phase, i.e., after run has been invoked on the FreeSpec,
 * will be met with a thrown TestRegistrationClosedException. The recommended style
 * of using FreeSpec is to register tests during object construction as is done in all
 * the examples shown here. If you keep to the recommended style, you should never see a
 * TestRegistrationClosedException.
 * 
 *
 * 
Ignored tests
 *
 * To support the common use case of temporarily disabling a test, with the
 * good intention of resurrecting the test at a later time, FreeSpec adds a method
 * ignore to strings that can be used instead of in to register a test. For example, to temporarily
 * disable the test with the name "A Stack should pop values in last-in-first-out order", just
 * change “in” into “ignore,” like this:
 * 

 *
 * 
 * package org.scalatest.examples.freespec.ignore
 * 
 * import org.scalatest.FreeSpec
 * 
 * class SetSpec extends FreeSpec {
 *   
 *   "A Set" - {
 *     "when empty" - {
 *       "should have size 0" ignore {
 *         assert(Set.empty.size === 0)
 *       }
 *       
 *       "should produce NoSuchElementException when head is invoked" in {
 *         intercept[NoSuchElementException] {
 *           Set.empty.head
 *         }
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * If you run this version of SetSpec with:
 * 
 *
 * 
 * scala> new SetSpec execute
 * 
 *
 * 

 * It will run only the second test and report that the first test was ignored:
 * 
 *
 * 
 * A Set
 *   when empty
 *   - should have size 0 !!! IGNORED !!!
 *   - should produce NoSuchElementException when head is invoked
 * 
 *
 * 

 * If you wish to temporarily ignore an entire suite of tests, you can annotate the test class with @Ignore, like this:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.ignoreall
 * 
 * import org.scalatest.FreeSpec
 * import org.scalatest.Ignore
 *
 * @Ignore
 * class SetSpec extends FreeSpec {
 *   
 *   "A Set" - {
 *     "when empty" - {
 *       "should have size 0" in {
 *         assert(Set.empty.size === 0)
 *       }
 *       
 *       "should produce NoSuchElementException when head is invoked" in {
 *         intercept[NoSuchElementException] {
 *           Set.empty.head
 *         }
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * When you mark a test class with a tag annotation, ScalaTest will mark each test defined in that class with that tag.
 * Thus, marking the SetSpec in the above example with the @Ignore tag annotation means that both tests
 * in the class will be ignored. If you run the above SetSpec in the Scala interpreter, you'll see:
 * 
 *
 * 
 * scala> new SetSpec execute
 * SetSpec:
 * A Set
 *   when empty
 *   - should have size 0 !!! IGNORED !!!
 *   - should produce NoSuchElementException when head is invoked !!! IGNORED !!!
 * 
 *
 * 

 * Note that marking a test class as ignored won't prevent it from being discovered by ScalaTest. Ignored classes
 * will be discovered and run, and all their tests will be reported as ignored. This is intended to keep the ignored
 * class visible, to encourage the developers to eventually fix and “un-ignore” it. If you want to
 * prevent a class from being discovered at all, use the DoNotDiscover annotation instead.
 * 
 *
 *
 * 
Informers
 *
 * 

 * One of the parameters to FreeSpec's run method is a Reporter, which
 * will collect and report information about the running suite of tests.
 * Information about suites and tests that were run, whether tests succeeded or failed, 
 * and tests that were ignored will be passed to the Reporter as the suite runs.
 * Most often the reporting done by default by FreeSpec'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.
 * 
 * 
 * 

 * One use case for the Informer is to pass more information about a specification to the reporter. For example,
 * the GivenWhenThen trait provides methods that use the implicit info provided by FreeSpec
 * to pass such information to the reporter. Here's an example:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.info
 * 
 * import collection.mutable
 * import org.scalatest._
 * 
 * class SetSpec extends FreeSpec with GivenWhenThen {
 *   
 *   "A mutable Set" - {
 *     "should allow an element to be added" in {
 *       Given("an empty mutable Set")
 *       val set = mutable.Set.empty[String]
 * 
 *       When("an element is added")
 *       set += "clarity"
 * 
 *       Then("the Set should have size 1")
 *       assert(set.size === 1)
 * 
 *       And("the Set should contain the added element")
 *       assert(set.contains("clarity"))
 * 
 *       info("That's all folks!")
 *     }
 *   }
 * }
 * 
 *
 * 

 * If you run this FreeSpec from the interpreter, you will see the following output:
 * 
 *
 * 
 * scala> new SetSpec execute
 * A mutable Set
 * - should allow an element to be added
 *   + Given an empty mutable Set 
 *   + When an element is added 
 *   + Then the Set should have size 1 
 *   + And the Set should contain the added element 
 *   + That's all folks! 
 * 
 *
 * 
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 it is intended to test, has not yet been implemented.
 * You can mark tests as pending in a FreeSpec like this:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.pending
 * 
 * import org.scalatest._
 * 
 * class SetSpec extends FreeSpec {
 * 
 *   "A Set" - {
 *     "when empty" - {
 *       "should have size 0" in (pending)
 *       
 *       "should produce NoSuchElementException when head is invoked" in {
 *         intercept[NoSuchElementException] {
 *           Set.empty.head
 *         }
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * If you run this version of SetSpec with:
 * 
 *
 * 
 * scala> new SetSpec execute
 * 
 *
 * 

 * It will run both tests but report that should have size 0 is pending. You'll see:
 * 
 *
 * 
 * A Set
 *   when empty
 *   - should have size 0 (pending)
 *   - should produce NoSuchElementException when head is invoked
 * 
 * 
 * 

 * 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 FreeSpec:
 * 
 *
 * 
 *  "The Scala language" - {
 *     "should add correctly" in { 
 *       Given("two integers")
 *       When("they are added")
 *       Then("the result is the sum of the two numbers")
 *       pending
 *     }
 *     // ...
 * 
 *
 * 

 * Would yield the following output when run in the interpreter:
 * 
 *
 * 
 * The Scala language
 * - should add correctly (pending)
 *   + Given two integers 
 *   + When they are added 
 *   + Then the result is the sum of the two numbers 
 * 
 *
 * 
Tagging tests
 *
 * A FreeSpec's tests may be classified into groups by tagging them with string names.
 * As with any suite, when executing a FreeSpec, groups of tests can
 * optionally be included and/or excluded. To tag a FreeSpec's tests,
 * you pass objects that extend class org.scalatest.Tag to methods
 * that register tests. Class Tag takes one parameter, a string name.  If you have
 * created tag annotation interfaces as described in the Tag documentation, then you
 * will probably want to use tag names on your test functions that match. To do so, simply 
 * pass the fully qualified names of the tag interfaces to the Tag constructor. For example, if you've
 * defined tag annotation interfaces with fully qualified names, com.mycompany.tags.SlowTest and
 * com.mycompany.tags.DbTest, then you could
 * create matching tags for FreeSpecs 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 tag FreeSpec tests like this:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.tagging
 * 
 * import org.scalatest.Tag
 * 
 * object SlowTest extends Tag("com.mycompany.tags.SlowTest")
 * object DbTest extends Tag("com.mycompany.tags.DbTest")
 * 
 * import org.scalatest.FreeSpec
 * 
 * class SetSpec extends FreeSpec {
 * 
 *   "A Set" - {
 *     "when empty" - {
 *       "should have size 0" taggedAs(SlowTest) in {
 *         assert(Set.empty.size === 0)
 *       }
 *       
 *       "should produce NoSuchElementException when head is invoked" taggedAs(SlowTest, DbTest) in {
 *         intercept[NoSuchElementException] {
 *           Set.empty.head
 *         }
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * This code marks both tests with the com.mycompany.tags.SlowTest tag, 
 * and the second test with the com.mycompany.tags.DbTest tag.
 * 
 *
 * 

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

 * It is recommended, though not required, that you create a corresponding tag annotation when you
 * create a Tag object. A tag annotation allows you to tag all the tests of a FreeSpec in
 * one stroke by annotating the class. For more information and examples, see the
 * documentation for class Tag.
 * 
 *
 * 
Shared fixtures
 *
 * 

 * A test fixture is composed of the objects and other artifacts (files, sockets, database
 * connections, etc.) tests use to do their work.
 * When multiple tests need to work with the same fixtures, it is important to try and avoid
 * duplicating the fixture code across those tests. The more code duplication you have in your
 * tests, the greater drag the tests will have on refactoring the actual production code.
 * ScalaTest recommends several techniques to eliminate such code duplication, and provides several
 * traits to help. Each technique is geared towards helping you reduce code duplication without introducing
 * instance vars, shared mutable objects, or other dependencies between tests. Eliminating shared
 * mutable state across tests will make your test code easier to reason about and more amenable for parallel
 * test execution.
 * 
 *
 * 

 * The following sections
 * describe these techniques, including explaining the recommended usage
 * for each. But first, here's a table summarizing the options:
 * 
 *
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
Technique
Recommended uses
get-fixture methods
Use when you need the same mutable fixture objects in multiple tests, and don't need to clean up after.
fixture-context objects
Use when you need different combinations of mutable fixture objects in different tests, and don't need to clean up after. 
OneInstancePerTest
Use when porting JUnit tests to ScalaTest, or if you prefer JUnit's approach to test isolation: running each test in its own instance of the test class.
withFixture(NoArgTest)
Use when you need to perform side effects at the beginning and end of all or most tests, or want to stack traits that perform such side-effects.
loan-fixture methods
Use when different tests need different fixtures that must be cleaned up afterwords.
withFixture(OneArgTest)
Use when all or most tests need the same fixtures that must be cleaned up afterwords.
BeforeAndAfter
Use when you need to perform the same side-effects before and/or after tests, rather than at the beginning or end of tests.
BeforeAndAfterEach
Use when you want to stack traits that perform the same side-effects before and/or after tests, rather than at the beginning or end of tests.
 *
 * 
 * 
Calling get-fixture methods
 *
 * 

 * If you need to create the same mutable fixture objects in multiple tests, and don't need to clean them up after using them, the simplest approach is to write one or
 * more get-fixture methods. A get-fixture method returns a new instance of a needed fixture object (or an holder object containing
 * multiple fixture objects) each time it is called. You can call a get-fixture method at the beginning of each
 * test that needs the fixture, storing the returned object or objects in local variables. Here's an example:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.getfixture
 * 
 * import org.scalatest.FreeSpec
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSpec extends FreeSpec {
 * 
 *   def fixture = 
 *     new {
 *       val builder = new StringBuilder("ScalaTest is ")
 *       val buffer = new ListBuffer[String]
 *     }
 *   
 *   "Testing" - {
 *     "should be easy" in {
 *       val f = fixture
 *       f.builder.append("easy!")
 *       assert(f.builder.toString === "ScalaTest is easy!")
 *       assert(f.buffer.isEmpty)
 *       f.buffer += "sweet"
 *     }
 *   
 *     "should be fun" in {
 *       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.
 * 
 *
 * 

 * If you need to configure fixture objects differently in different tests, you can pass configuration into the get-fixture method. For example, if you could pass
 * in an initial value for a mutable fixture object as a parameter to the get-fixture method.
 * 
 *
 * 
 * 
Instantiating fixture-context objects 
 *
 * 

 * An alternate technique that is especially useful when different tests need different combinations of fixture objects is to define the fixture objects as instance variables
 * of fixture-context objects whose instantiation forms the body of tests. Like get-fixture methods, fixture-context objects are only
 * appropriate if you don't need to clean up the fixtures after using them.
 * 
 *
 * To use this technique, you define instance variables intialized with fixture objects in traits and/or classes, then in each test instantiate an object that
 * contains just the fixture objects needed by the test. Traits allow you to mix together just the fixture objects needed by each test, whereas classes
 * allow you to pass data in via a constructor to configure the fixture objects. Here's an example in which fixture objects are partitioned into two traits
 * and each test just mixes together the traits it needs:
 * 

 *
 * 
 * package org.scalatest.examples.freespec.fixturecontext
 * 
 * import collection.mutable.ListBuffer
 * import org.scalatest.FreeSpec
 * 
 * class ExampleSpec extends FreeSpec {
 * 
 *   trait Builder {
 *     val builder = new StringBuilder("ScalaTest is ")
 *   }
 * 
 *   trait Buffer {
 *     val buffer = ListBuffer("ScalaTest", "is")
 *   }
 * 
 *   "Testing" - {
 *     // This test needs the StringBuilder fixture
 *     "should be productive" in new Builder {
 *       builder.append("productive!")
 *       assert(builder.toString === "ScalaTest is productive!")
 *     }
 *   }
 * 
 *   "Test code" - {
 *     // This test needs the ListBuffer[String] fixture
 *     "should be readable" in new Buffer {
 *       buffer += ("readable!")
 *       assert(buffer === List("ScalaTest", "is", "readable!"))
 *     }
 * 
 *     // This test needs both the StringBuilder and ListBuffer
 *     "should be clear and concise" in new Builder with Buffer {
 *       builder.append("clear!")
 *       buffer += ("concise!")
 *       assert(builder.toString === "ScalaTest is clear!")
 *       assert(buffer === List("ScalaTest", "is", "concise!"))
 *     }
 *   }
 * }
 * 
 *
 * 
 * 
Mixing in OneInstancePerTest
 *
 * 

 * If every test method requires the same set of
 * mutable fixture objects, and none require cleanup, 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:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.oneinstancepertest
 * 
 * import org.scalatest._
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSuite extends FreeSpec with OneInstancePerTest {
 * 
 *   val builder = new StringBuilder("ScalaTest is ")
 *   val buffer = new ListBuffer[String]
 * 
 *   "Testing" - {
 *     "should be easy" in {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     "should be fun" in {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *     } 
 *   }
 * }
 * 
 *
 * 

 * One way to think of OneInstancePerTest is that the entire Suite instance is like a fixture-context object,
 * but with the difference that the test code doesn't run during construction as it does with the real fixture-context object technique. Because this trait emulates JUnit's manner
 * of running tests, this trait can be helpful when porting JUnit tests to ScalaTest. The primary intended use of OneInstancePerTest is to serve as a supertrait for
 * ParallelTestExecution and the path traits, but you can also mix it in
 * directly to help you port JUnit tests to ScalaTest or if you prefer JUnit's approach to test isolation.
 * 
 *
 * 
 * 
Overriding withFixture(NoArgTest)
 *
 * 

 * Although the get-fixture method, fixture-context object, and OneInstancePerTest approaches take care of setting up a fixture at the beginning of each
 * test, they don't address the problem of cleaning up a fixture at the end of the test. If you just need to perform a side-effect at the beginning or end of
 * a test, and don't need to actually pass any fixture objects into the test, you can override withFixture(NoArgTest), one of ScalaTest's
 * lifecycle methods defined in trait Suite.
 * 
 *
 * 

 * Trait Suite's implementation of runTest passes a no-arg test function to withFixture(NoArgTest). It is withFixture's
 * responsibility to invoke that test function. Suite's implementation of withFixture simply
 * invokes the function, like this:
 * 
 *
 * 
 * // Default implementation in trait Suite
 * protected def withFixture(test: NoArgTest) {
 *   test()
 * }
 * 
 *
 * 

 * You can, therefore, override withFixture to perform setup before and/or 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, because the exception that causes a test to fail will propagate through withFixture back
 * to runTest. (In other words, if the test fails, the test function invoked by withFixture will throw an exception.)
 * 
 *
 * 

 * The withFixture method is designed to be stacked, and to enable this, you should always call the super implementation
 * of withFixture, and let it invoke the test function rather than invoking the test function directly. In other words, instead of writing
 * “test()”, you should write “super.withFixture(test)”, like this:
 * 
 *
 * 
 * // Your implementation
 * override def withFixture(test: NoArgTest) {
 *   // Perform setup
 *   try super.withFixture(test) // Invoke the test function
 *   finally {
 *     // Perform cleanup
 *   }
 * }
 * 
 *
 * 

 * Here's an example in which withFixture(NoArgTest) is used to take a snapshot of the working directory if a test fails, and 
 * and send that information to the reporter:
 * 
 *
 * 
 * package org.scalatest.examples.freespec.noargtest
 * 
 * import java.io.File
 * import org.scalatest.FreeSpec
 * 
 * class ExampleSpec extends FreeSpec {
 * 
 *   override def withFixture(test: NoArgTest) {
 * 
 *     try super.withFixture(test)
 *     catch {
 *       case e: Exception =>
 *         val currDir = new File(".")
 *         val fileNames = currDir.list()
 *         info("Dir snapshot: " + fileNames.mkString(", "))
 *         throw e
 *     }
 *   }
 * 
 *   "This test" - {
 *     "should succeed" in {
 *       assert(1 + 1 === 2)
 *     }
 * 
 *     "should fail" in {
 *       assert(1 + 1 === 3)
 *     }
 *   }
 * }
 * 
 *
 * 

 * Running this version of ExampleSuite in the interpreter in a directory with two files, hello.txt and world.txt
 * would give the following output:
 * 
 *
 * 
 * scala> new ExampleSuite execute
 * ExampleSuite:
 * This test
 * - should succeed
 * - should fail *** FAILED ***
 *   2 did not equal 3 (:33)
 *   + Dir snapshot: hello.txt, world.txt 
 * 
 *
 * 

 * Note that the NoArgTest passed to withFixture, in addition to
 * an apply method that executes the test, also includes the test name and the config
 * map passed to runTest. Thus you can also use the test name and configuration objects in your withFixture
 * implementation.
 * 
 *
 * 
 * 
Calling loan-fixture methods
 *
 * 

 * If you need to both pass a fixture object into a test and perform cleanup at the end of the test, you'll need to use the loan pattern.
 * If different tests need different fixtures that require cleanup, you can implement the loan pattern directly by writing loan-fixture methods.
 * A loan-fixture method takes a function whose body forms part or all of a test's code. It creates a fixture, passes it to the test code by invoking the
 * function, then cleans up the fixture after the function returns.
 * 
 *
 * 

 * The following example shows three tests that use two fixtures, a database and a file. Both require cleanup after, so each is provided via a
 * loan-fixture method. (In this example, the database is simulated with a StringBuffer.)
 * 
 *
 * 
 * package org.scalatest.examples.freespec.loanfixture
 * 
 * import java.util.concurrent.ConcurrentHashMap
 * 
 * object DbServer { // Simulating a database server
 *   type Db = StringBuffer
 *   private val databases = new ConcurrentHashMap[String, Db]
 *   def createDb(name: String): Db = {
 *     val db = new StringBuffer
 *     databases.put(name, db)
 *     db
 *   }
 *   def removeDb(name: String) {
 *     databases.remove(name)
 *   }
 * }
 * 
 * import org.scalatest.FreeSpec
 * import DbServer._
 * import java.util.UUID.randomUUID
 * import java.io._
 * 
 * class ExampleSpec extends FreeSpec {
 * 
 *   def withDatabase(testCode: Db => Any) {
 *     val dbName = randomUUID.toString
 *     val db = createDb(dbName) // create the fixture
 *     try {
 *       db.append("ScalaTest is ") // perform setup
 *       testCode(db) // "loan" the fixture to the test
 *     }
 *     finally removeDb(dbName) // clean up the fixture
 *   }
 * 
 *   def withFile(testCode: (File, FileWriter) => Any) {
 *     val file = File.createTempFile("hello", "world") // create the fixture
 *     val writer = new FileWriter(file)
 *     try {
 *       writer.write("ScalaTest is ") // set up the fixture
 *       testCode(file, writer) // "loan" the fixture to the test
 *     }
 *     finally writer.close() // clean up the fixture
 *   }
 * 
 *   "Testing" - {
 *     // This test needs the file fixture
 *     "should be productive" in withFile { (file, writer) =>
 *       writer.write("productive!")
 *       writer.flush()
 *       assert(file.length === 24)
 *     }
 *   }
 *   
 *   "Test code" - {
 *     // This test needs the database fixture
 *     "should be readable" in withDatabase { db =>
 *       db.append("readable!")
 *       assert(db.toString === "ScalaTest is readable!")
 *     }
 * 
 *     // This test needs both the file and the database
 *     "should be clear and concise" in withDatabase { db =>
 *       withFile { (file, writer) => // loan-fixture methods compose
 *         db.append("clear!")
 *         writer.write("concise!")
 *         writer.flush()
 *         assert(db.toString === "ScalaTest is clear!")
 *         assert(file.length === 21)
 *       }
 *     }
 *   }
 * }
 * 
 *
 * 

 * As demonstrated by the last test, loan-fixture methods compose. Not only do loan-fixture methods allow you to
 * give each test the fixture it needs, they allow you to give a test multiple fixtures and clean everything up afterwords.
 * 
 *
 * 

 * Also demonstrated in this example is the technique of giving each test its own "fixture sandbox" to play in. When your fixtures
 * involve external side-effects, like creating files or databases, it is a good idea to give each file or database a unique name as is
 * done in this example. This keeps tests completely isolated, allowing you to run them in parallel if desired.
 * 
 *
 * 

 * withFixture(test.toNoArgTest(theFixture))
 * 

 * package org.scalatest.examples.freespec.oneargtest
 * 
 * import org.scalatest.fixture
 * import java.io._
 * 
 * class ExampleSpec extends fixture.FreeSpec {
 * 
 *   case class F(file: File, writer: FileWriter)
 *   type FixtureParam = F
 * 
 *   def withFixture(test: OneArgTest) {
 *
 *     // create the fixture
 *     val file = File.createTempFile("hello", "world")
 *     val writer = new FileWriter(file)
 *     val theFixture = F(file, writer)
 *
 *     try {
 *       writer.write("ScalaTest is ") // set up the fixture
 *       withFixture(test.toNoArgTest(theFixture)) // "loan" the fixture to the test
 *     }
 *     finally writer.close() // clean up the fixture
 *   }
 *
 *   "Testing" - {
 *     "should be easy" in { f =>
 *       f.writer.write("easy!")
 *       f.writer.flush()
 *       assert(f.file.length === 18)
 *     }
 * 
 *     "should be fun" in { f =>
 *       f.writer.write("fun!")
 *       f.writer.flush()
 *       assert(f.file.length === 17)
 *     }
 *   } 
 * }
 * 

 * package org.scalatest.examples.freespec.beforeandafter
 * 
 * import org.scalatest.FreeSpec
 * import org.scalatest.BeforeAndAfter
 * import collection.mutable.ListBuffer
 * 
 * class ExampleSpec extends FreeSpec with BeforeAndAfter {
 * 
 *   val builder = new StringBuilder
 *   val buffer = new ListBuffer[String]
 * 
 *   before {
 *     builder.append("ScalaTest is ")
 *   }
 * 
 *   after {
 *     builder.clear()
 *     buffer.clear()
 *   }
 * 
 *   "Testing" - {
 *     "should be easy" in {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     "should be fun" in {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *     }
 *   }
 * }
 * 

 * package org.scalatest.examples.freespec.composingwithfixture
 * 
 * import org.scalatest._
 * import collection.mutable.ListBuffer
 * 
 * trait Builder extends SuiteMixin { 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 SuiteMixin { 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 FreeSpec with Builder with Buffer {
 * 
 *   "Testing" - {
 *     "should be easy" in {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     "should be fun" in {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *       buffer += "clear"
 *     }
 *   }
 * }
 * 

 * class Example2Suite extends Suite with Buffer with Builder
 * 

 * class Example3Suite extends Suite with Builder
 * 

 * package org.scalatest.examples.freespec.composingbeforeandaftereach
 * 
 * import org.scalatest._
 * 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 FreeSpec with Builder with Buffer {
 * 
 *   "Testing" - {
 *     "should be easy" in {
 *       builder.append("easy!")
 *       assert(builder.toString === "ScalaTest is easy!")
 *       assert(buffer.isEmpty)
 *       buffer += "sweet"
 *     }
 * 
 *     "should be fun" in {
 *       builder.append("fun!")
 *       assert(builder.toString === "ScalaTest is fun!")
 *       assert(buffer.isEmpty)
 *       buffer += "clear"
 *     }
 *   }
 * }
 * 

 * 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(", ", ", ")")
 * }
 * 

 * trait StackBehaviors { this: FreeSpec =>
 * 
 *   def nonEmptyStack(newStack: => Stack[Int], lastItemAdded: Int) {
 *
 *     "be non-empty" in {
 *       assert(!newStack.empty)
 *     }
 *
 *     "return the top item on peek" in {
 *       assert(newStack.peek === lastItemAdded)
 *     }
 *
 *     "not remove the top item on peek" in {
 *       val stack = newStack
 *       val size = stack.size
 *       assert(stack.peek === lastItemAdded)
 *       assert(stack.size === size)
 *     }
 *
 *     "remove the top item on pop" in {
 *       val stack = newStack
 *       val size = stack.size
 *       assert(stack.pop === lastItemAdded)
 *       assert(stack.size === size - 1)
 *     }
 *   }
 *
 *   def nonFullStack(newStack: => Stack[Int]) {
 *
 *     "not be full" in {
 *       assert(!newStack.full)
 *     }
 *
 *     "add to the top on push" in {
 *       val stack = newStack
 *       val size = stack.size
 *       stack.push(7)
 *       assert(stack.size === size + 1)
 *       assert(stack.peek === 7)
 *     }
 *   }
 * }
 * 

 * behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
 * behave like nonFullStack(stackWithOneItem)
 * 

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

 * class SharedTestExampleSpec extends FreeSpec with StackBehaviors {
 * 
 *   // Stack fixture creation methods
 *   def emptyStack = new Stack[Int]
 * 
 *   def fullStack = {
 *     val stack = new Stack[Int]
 *     for (i <- 0 until stack.MAX)
 *       stack.push(i)
 *     stack
 *   }
 * 
 *   def stackWithOneItem = {
 *     val stack = new Stack[Int]
 *     stack.push(9)
 *     stack
 *   }
 * 
 *   def stackWithOneItemLessThanCapacity = {
 *     val stack = new Stack[Int]
 *     for (i <- 1 to 9)
 *       stack.push(i)
 *     stack
 *   }
 * 
 *   val lastValuePushed = 9
 * 
 *   "A Stack" - {
 *     "when empty" - {
 *       "should be empty" in {
 *         assert(emptyStack.empty)
 *       }
 * 
 *       "should complain on peek" in {
 *         intercept[IllegalStateException] {
 *           emptyStack.peek
 *         }
 *       }
 *
 *       "should complain on pop" in {
 *         intercept[IllegalStateException] {
 *           emptyStack.pop
 *         }
 *       }
 *     }
 * 
 *     "when it contains one item" - {
 *       "should" - {
 *         behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
 *         behave like nonFullStack(stackWithOneItem)
 *       }
 *     }
 *     
 *     "when it contains one item less than capacity" - {
 *       "should" - {
 *         behave like nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed)
 *         behave like nonFullStack(stackWithOneItemLessThanCapacity)
 *       }
 *     }
 * 
 *     "when full" - {
 *       "should be full" in {
 *         assert(fullStack.full)
 *       }
 * 
 *       "should" - {
 *         behave like nonEmptyStack(fullStack, lastValuePushed)
 *       }
 * 
 *       "should complain on a push" in {
 *         intercept[IllegalStateException] {
 *           fullStack.push(10)
 *         }
 *       }
 *     }
 *   }
 * }
 * 

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

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

     * "complain on peek" taggedAs(SlowTest) in { ... }
     *                                       ^
     * 

     * "complain on peek" taggedAs(SlowTest) is (pending)
     *                                       ^
     * 

     * "complain on peek" taggedAs(SlowTest) ignore { ... }
     *                                       ^
     * 

     * "complain on peek" in { ... }
     *                    ^
     * 

     * "complain on peek" ignore { ... }
     *                    ^
     * 

     * "complain on peek" is (pending)
     *                    ^
     * 

     * "complain on peek" taggedAs(SlowTest) in { ... }
     *                    ^
     * 

   * import org.scalatest.FreeSpec
   *
   * class StackSpec extends FreeSpec {
   *   "A Stack" - {
   *     "when not empty" - {
   *       "must allow me to pop" in {}
   *     }
   *     "when not full" - {
   *       "must allow me to push" in {}
   *     }
   *   }
   * }
   * 

   * "A Stack when not empty must allow me to pop"
   * "A Stack when not full must allow me to push"
   * 

   * behave like nonFullStack(stackWithOneItem)
   * ^
   * 

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