org.scalatest.FeatureSpec.scala Maven / Gradle / Ivy
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/*
* Copyright 2001-2012 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 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.anExceptionThatShouldCauseAnAbort
import Suite.autoTagClassAnnotations
/**
* 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.
*
*
* Recommended Usage:
* Class FeatureSpec is primarily intended for acceptance testing, including facilitating the process of programmers working alongside non-programmers to
* define the acceptance requirements.
*
*
*
* Although not required, FeatureSpec is often used together with GivenWhenThen to express acceptance requirements
* in more detail. Here's an example:
*
*
*
*
* package org.scalatest.examples.featurespec
*
* import org.scalatest._
*
* class TVSet {
* private var on: Boolean = false
* def isOn: Boolean = on
* def pressPowerButton() {
* on = !on
* }
* }
*
* class TVSetSpec extends FeatureSpec with GivenWhenThen {
*
* info("As a TV set owner")
* info("I want to be able to turn the TV on and off")
* info("So I can watch TV when I want")
* info("And save energy when I'm not watching TV")
*
* feature("TV power button") {
* scenario("User presses power button when TV is off") {
*
* Given("a TV set that is switched off")
* val tv = new TVSet
* assert(!tv.isOn)
*
* When("the power button is pressed")
* tv.pressPowerButton()
*
* Then("the TV should switch on")
* assert(tv.isOn)
* }
*
* scenario("User presses power button when TV is on") {
*
* Given("a TV set that is switched on")
* val tv = new TVSet
* tv.pressPowerButton()
* assert(tv.isOn)
*
* When("the power button is pressed")
* tv.pressPowerButton()
*
* Then("the TV should switch off")
* assert(!tv.isOn)
* }
* }
* }
*
*
*
* Note: for more information on the calls to Given, When, and Then, see the documentation
* for trait GivenWhenThen and the Informers section below.
*
*
*
* 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 Set. The feature being specified and tested is
* the behavior of a Set when it is empty and head is invoked. 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, were you to runTVSetSpec from within the Scala interpreter:
*
*
*
* scala> new TVSetSpec execute
*
*
*
* You would see:
*
*
*
* TVSetSpec:
* As a TV set owner
* I want to be able to turn the TV on and off
* So I can watch TV when I want
* And save energy when I'm not watching TV
* Feature: TV power button
* Scenario: User presses power button when TV is off
* Given a TV set that is switched off
* When the power button is pressed
* Then the TV should switch on
* Scenario: User presses power button when TV is on
* Given a TV set that is switched on
* When the power button is pressed
* Then the TV should switch off
*
*
*
* Or, to run just the “Feature: TV power button Scenario: User presses power button when TV is on” method, you could pass that test's name, or any unique substring of the
* name, such as "TV is on". Here's an example:
*
*
*
* scala> new TVSetSpec execute "TV is on"
* TVSetSpec:
* As a TV set owner
* I want to be able to turn the TV on and off
* So I can watch TV when I want
* And save energy when I'm not watching TV
* Feature: TV power button
* Scenario: User presses power button when TV is on
* Given a TV set that is switched on
* When the power button is pressed
* Then the TV should switch off
*
*
*
* You can also pass to execute a config map of key-value
* pairs, which will be passed down into suites and tests, as well as other parameters that configure the run itself.
* For more information on running in the Scala interpreter, see the documentation for execute (below) and the
* ScalaTest shell.
*
*
*
* The execute method invokes a run method that takes two
* parameters. This run method, which actually executes the suite, will usually be invoked by a test runner, such
* as run, tools.Runner, a build tool, or an IDE.
*
*
*
* See also: Getting started with FeatureSpec.
*
*
*
* Note: Trait FeatureSpec's syntax is in part inspired by Cucumber, a Ruby BDD framework.
*
*
* 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:
*
*
*
* package org.scalatest.examples.featurespec.ignore
*
* import org.scalatest.FeatureSpec
*
* class TVSet {
* private var on: Boolean = false
* def isOn: Boolean = on
* def pressPowerButton() {
* on = !on
* }
* }
*
* class TVSetSpec extends FeatureSpec {
*
* feature("TV power button") {
* ignore("User presses power button when TV is off") {
* val tv = new TVSet
* assert(!tv.isOn)
* tv.pressPowerButton()
* assert(tv.isOn)
* }
*
* scenario("User presses power button when TV is on") {
* val tv = new TVSet
* tv.pressPowerButton()
* assert(tv.isOn)
* tv.pressPowerButton()
* assert(!tv.isOn)
* }
* }
* }
*
*
*
* If you run this version of SetSpec with:
*
*
*
* scala> new TVSetSpec execute
*
*
*
* It will run only the second scenario and report that the first scenario was ignored:
*
*
*
* TVSetSpec:
* Feature: TV power button
* Scenario: User presses power button when TV is off !!! IGNORED !!!
* Scenario: User presses power button when TV is on
*
*
* Informers
*
*
* One of the parameters to FeatureSpec'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 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.
*
*
*
* 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. You can see this in action in the initial example of this trait's documentation.
*
*
* 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:
*
*
*
* package org.scalatest.examples.featurespec.pending
*
* import org.scalatest.FeatureSpec
*
* class TVSet {
* private var on: Boolean = false
* def isOn: Boolean = on
* def pressPowerButton() {
* on = !on
* }
* }
*
* class TVSetSpec extends FeatureSpec {
*
* feature("TV power button") {
*
* scenario("User presses power button when TV is off") (pending)
*
* scenario("User presses power button when TV is on") {
* val tv = new TVSet
* tv.pressPowerButton()
* assert(tv.isOn)
* tv.pressPowerButton()
* assert(!tv.isOn)
* }
* }
* }
*
*
*
* (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 TVSetSpec with:
*
*
*
* scala> new TVSetSpec execute
*
*
*
* It will run both tests, but report that When empty should have size 0 is pending. You'll see:
*
*
*
* TVSetSpec:
* Feature: TV power button
* Scenario: User presses power button when TV is off (pending)
* Scenario: User presses power button when TV is on
*
*
*
* 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:
*
*
*
* package org.scalatest.examples.featurespec.infopending
*
* import org.scalatest._
*
* class TVSet {
* private var on: Boolean = false
*
* def isOn: Boolean = on
*
* def pressPowerButton() {
* on = !on
* }
* }
*
* class TVSetSpec extends FeatureSpec with GivenWhenThen {
*
* info("As a TV set owner")
* info("I want to be able to turn the TV on and off")
* info("So I can watch TV when I want")
* info("And save energy when I'm not watching TV")
*
* feature("TV power button") {
* scenario("User presses power button when TV is off") {
* Given("a TV that is switched off")
* When("the power button is pressed")
* Then("the TV should switch on")
* pending
* }
*
* scenario("User presses power button when TV is on") {
* Given("a TV that is switched on")
* When("the power button is pressed")
* Then("the TV should switch off")
* pending
* }
* }
* }
*
*
*
* Would yield the following output when run in the interpreter:
*
*
*
* scala> new TVSetSpec execute
* TVSetSpec:
* As a TV set owner
* I want to be able to turn the TV on and off
* So I can watch TV when I want
* And save energy when I'm not watching TV
* Feature: TV power button
* Scenario: User presses power button when TV is off (pending)
* Given a TV that is switched off
* When the power button is pressed
* Then the TV should switch on
* Scenario: User presses power button when TV is on (pending)
* Given a TV that is switched on
* When the power button is pressed
* Then the TV should switch off
*
*
* 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 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 FeatureSpecs like this:
*
*
*
* package org.scalatest.examples.featurespec.tagging
*
* 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 TVSet {
* private var on: Boolean = false
* def isOn: Boolean = on
* def pressPowerButton() {
* on = !on
* }
* }
*
* class TVSetSpec extends FeatureSpec {
*
* feature("TV power button") {
* scenario("User presses power button when TV is off", SlowTest) {
* val tv = new TVSet
* assert(!tv.isOn)
* tv.pressPowerButton()
* assert(tv.isOn)
* }
*
* scenario("User presses power button when TV is on", SlowTest, DbTest) {
* val tv = new TVSet
* tv.pressPowerButton()
* assert(tv.isOn)
* tv.pressPowerButton()
* assert(!tv.isOn)
* }
* }
* }
*
*
*
* 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 FeatureSpec 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. OneInstancePerTestUse 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 afterwards. withFixture(OneArgTest)Use when all or most tests need the same fixtures that must be cleaned up afterwards. BeforeAndAfterUse when you need to perform the same side-effects before and/or after tests, rather than at the beginning or end of tests. BeforeAndAfterEachUse 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.featurespec.getfixture
*
* import org.scalatest.FeatureSpec
* import collection.mutable.ListBuffer
*
* class ExampleSpec extends FeatureSpec {
*
* def fixture =
* new {
* val builder = new StringBuilder("ScalaTest is designed to ")
* val buffer = new ListBuffer[String]
* }
*
* feature("Simplicity") {
* scenario("User needs to read test code written by others") {
* val f = fixture
* f.builder.append("encourage clear code!")
* assert(f.builder.toString === "ScalaTest is designed to encourage clear code!")
* assert(f.buffer.isEmpty)
* f.buffer += "sweet"
* }
*
* scenario("User needs to understand what the tests are doing") {
* val f = fixture
* f.builder.append("be easy to reason about!")
* assert(f.builder.toString === "ScalaTest is designed to be easy to reason about!")
* 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.featurespec.fixturecontext
*
* import collection.mutable.ListBuffer
* import org.scalatest.FeatureSpec
*
* class ExampleSpec extends FeatureSpec {
*
* trait Builder {
* val builder = new StringBuilder("ScalaTest is designed to ")
* }
*
* trait Buffer {
* val buffer = ListBuffer("ScalaTest", "is", "designed", "to")
* }
*
* feature("Simplicity") {
* // This test needs the StringBuilder fixture
* scenario("User needs to read test code written by others") {
* new Builder {
* builder.append("encourage clear code!")
* assert(builder.toString === "ScalaTest is designed to encourage clear code!")
* }
* }
*
* // This test needs the ListBuffer[String] fixture
* scenario("User needs to understand what the tests are doing") {
* new Buffer {
* buffer += ("be", "easy", "to", "reason", "about!")
* assert(buffer === List("ScalaTest", "is", "designed", "to", "be", "easy", "to", "reason", "about!"))
* }
* }
*
* // This test needs both the StringBuilder and ListBuffer
* scenario("User needs to write tests") {
* new Builder with Buffer {
* builder.append("be easy to learn!")
* buffer += ("be", "easy", "to", "remember", "how", "to", "write!")
* assert(builder.toString === "ScalaTest is designed to be easy to learn!")
* assert(buffer === List("ScalaTest", "is", "designed", "to", "be", "easy",
* "to", "remember", "how", "to", "write!"))
* }
* }
* }
* }
*
*
*
* 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.featurespec.oneinstancepertest
*
* import org.scalatest._
* import collection.mutable.ListBuffer
*
* class ExampleSuite extends FeatureSpec with OneInstancePerTest {
*
* val builder = new StringBuilder("ScalaTest is designed to ")
* val buffer = new ListBuffer[String]
*
* feature("Simplicity") {
* scenario("User needs to read test code written by others") {
* builder.append("encourage clear code!")
* assert(builder.toString === "ScalaTest is designed to encourage clear code!")
* assert(buffer.isEmpty)
* buffer += "sweet"
* }
*
* scenario("User needs to understand what the tests are doing") {
* builder.append("be easy to reason about!")
* assert(builder.toString === "ScalaTest is designed to be easy to reason about!")
* 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.featurespec.noargtest
*
* import java.io.File
* import org.scalatest.FeatureSpec
*
* class ExampleSpec extends FeatureSpec {
*
* 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
* }
* }
*
* scenario("This scenario should succeed") {
* assert(1 + 1 === 2)
* }
*
* scenario("This scenario should fail") {
* 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 ExampleSpec execute
* ExampleSpec:
* Scenario: This scenario should succeed
* Scenario: This scenario should fail *** FAILED ***
* 2 did not equal 3 (:115)
* + 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.featurespec.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.FeatureSpec
* import DbServer._
* import java.util.UUID.randomUUID
* import java.io._
*
* class ExampleSpec extends FeatureSpec {
*
* def withDatabase(testCode: Db => Any) {
* val dbName = randomUUID.toString
* val db = createDb(dbName) // create the fixture
* try {
* db.append("ScalaTest is designed to ") // 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 designed to ") // set up the fixture
* testCode(file, writer) // "loan" the fixture to the test
* }
* finally writer.close() // clean up the fixture
* }
*
* feature("Simplicity") {
* // This test needs the file fixture
* scenario("User needs to read test code written by others") {
* withFile { (file, writer) =>
* writer.write("encourage clear code!")
* writer.flush()
* assert(file.length === 46)
* }
* }
* // This test needs the database fixture
* scenario("User needs to understand what the tests are doing") {
* withDatabase { db =>
* db.append("be easy to reason about!")
* assert(db.toString === "ScalaTest is designed to be easy to reason about!")
* }
* }
* // This test needs both the file and the database
* scenario("User needs to write tests") {
* withDatabase { db =>
* withFile { (file, writer) => // loan-fixture methods compose
* db.append("be easy to learn!")
* writer.write("be easy to remember how to write!")
* writer.flush()
* assert(db.toString === "ScalaTest is designed to be easy to learn!")
* assert(file.length === 58)
* }
* }
* }
* }
* }
*
*
*
* 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 afterwards.
*
*
*
* 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.
*
*
* Overriding withFixture(OneArgTest)
*
*
* If all or most tests need the same fixture, you can avoid some of the boilerplate of the loan-fixture method approach by using a fixture.Suite
* and overriding withFixture(OneArgTest).
* Each test in a fixture.Suite 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.
*
* To enable the stacking of traits that define withFixture(NoArgTest), it is a good idea to let
* withFixture(NoArgTest) invoke the test function instead of invoking the test
* function directly. To do so, you'll need to convert the OneArgTest to a NoArgTest. You can do that by passing
* the fixture object to the toNoArgTest method of OneArgTest. In other words, instead of
* writing “test(theFixture)”, you'd delegate responsibility for
* invoking the test function to the withFixture(NoArgTest) method of the same instance by writing:
*
* withFixture(test.toNoArgTest(theFixture)) ** *
* Here's a complete example: *
* *
* package org.scalatest.examples.featurespec.oneargtest
*
* import org.scalatest.fixture
* import java.io._
*
* class ExampleSpec extends fixture.FeatureSpec {
*
* case class FixtureParam(file: File, writer: FileWriter)
*
* def withFixture(test: OneArgTest) = {
*
* // create the fixture
* val file = File.createTempFile("hello", "world")
* val writer = new FileWriter(file)
* val theFixture = FixtureParam(file, writer)
*
* try {
* writer.write("ScalaTest is designed to be ") // set up the fixture
* withFixture(test.toNoArgTest(theFixture)) // "loan" the fixture to the test
* }
* finally writer.close() // clean up the fixture
* }
*
* feature("Simplicity") {
* scenario("User needs to read test code written by others") { f =>
* f.writer.write("encourage clear code!")
* f.writer.flush()
* assert(f.file.length === 49)
* }
*
* scenario("User needs to understand what the tests are doing") { f =>
* f.writer.write("be easy to reason about!")
* f.writer.flush()
* assert(f.file.length === 52)
* }
* }
* }
*
*
*
* In this example, the tests actually required two fixture objects, a File and a FileWriter. In such situations you can
* simply define the FixtureParam type to be a tuple containing the objects, or as is done in this example, a case class containing
* the objects. For more information on the withFixture(OneArgTest) technique, see the documentation for fixture.Suite.
*
Mixing in BeforeAndAfter
*
*
* In all the shared fixture examples shown so far, the activities of creating, setting up, and cleaning up the fixture objects have been
* performed during the test. This means that if an exception occurs during any of these activities, it will be reported as a test failure.
* Sometimes, however, you may want setup to happen before the test starts, and cleanup after the test has completed, so that if an
* exception occurs during setup or cleanup, the entire suite aborts and no more tests are attempted. The simplest way to accomplish this in ScalaTest is
* to mix in trait BeforeAndAfter. 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:
*
* package org.scalatest.examples.featurespec.beforeandafter
*
* import org.scalatest._
* import collection.mutable.ListBuffer
*
* class ExampleSpec extends FeatureSpec with BeforeAndAfter {
*
* val builder = new StringBuilder
* val buffer = new ListBuffer[String]
*
* before {
* builder.append("ScalaTest is designed to ")
* }
*
* after {
* builder.clear()
* buffer.clear()
* }
*
* feature("Simplicity") {
* scenario("User needs to read test code written by others") {
* builder.append("encourage clear code!")
* assert(builder.toString === "ScalaTest is designed to encourage clear code!")
* assert(buffer.isEmpty)
* buffer += "sweet"
* }
*
* scenario("User needs to understand what the tests are doing") {
* builder.append("be easy to reason about!")
* assert(builder.toString === "ScalaTest is designed to be easy to reason about!")
* assert(buffer.isEmpty)
* }
* }
* }
*
*
*
* Note that the only way before and after code can communicate with test code is via some side-effecting mechanism, commonly by
* reassigning instance vars or by changing the state of mutable objects held from instance vals (as in this example). If using
* instance vars or mutable objects held from instance vals you wouldn't be able to run tests in parallel in the same instance
* of the test class unless you synchronized access to the shared, mutable state. This is why ScalaTest's ParallelTestExecution trait extends
* OneInstancePerTest. By running each test in its own instance of the class, each test has its own copy of the instance variables, so you
* don't need to synchronize. If you mixed ParallelTestExecution into the ExampleSuite above, the tests would run in parallel just fine
* without any synchronization needed on the mutable StringBuilder and ListBuffer[String] objects.
*
* Although BeforeAndAfter provides a minimal-boilerplate way to execute code before and after tests, it isn't designed to enable stackable
* traits, because the order of execution would be non-obvious. If you want to factor out before and after code that is common to multiple test suites, you
* should use trait BeforeAndAfterEach instead, as shown later in the next section,
* composing fixtures by stacking traits.
*
Composing fixtures by stacking 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:
*
* package org.scalatest.examples.featurespec.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 designed to ")
* 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 FeatureSpec with Builder with Buffer {
*
* feature("Simplicity") {
* scenario("User needs to read test code written by others") {
* builder.append("encourage clear code!")
* assert(builder.toString === "ScalaTest is designed to encourage clear code!")
* assert(buffer.isEmpty)
* buffer += "clear"
* }
*
* scenario("User needs to understand what the tests are doing") {
* builder.append("be easy to reason about!")
* assert(builder.toString === "ScalaTest is designed to be easy to reason about!")
* assert(buffer.isEmpty)
* buffer += "easy"
* }
* }
* }
*
*
*
* By mixing in both the Builder and Buffer traits, ExampleSuite 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 Example2Suite extends Suite with Buffer with Builder ** *
* And if you only need one fixture you mix in only that trait: *
* ** class Example3Suite extends Suite 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:
*
* package org.scalatest.examples.featurespec.composingbeforeandaftereach
*
* import org.scalatest._
* import collection.mutable.ListBuffer
*
* trait Builder extends BeforeAndAfterEach { this: Suite =>
*
* val builder = new StringBuilder
*
* override def beforeEach() {
* builder.append("ScalaTest is designed to ")
* 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("Simplicity") {
* scenario("User needs to read test code written by others") {
* builder.append("encourage clear code!")
* assert(builder.toString === "ScalaTest is designed to encourage clear code!")
* assert(buffer.isEmpty)
* buffer += "clear"
* }
*
* scenario("User needs to understand what the tests are doing") {
* builder.append("be easy to reason about!")
* assert(builder.toString === "ScalaTest is designed to be easy to reason about!")
* assert(buffer.isEmpty)
* buffer += "easy"
* }
* }
* }
*
*
*
* 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.afterEach throws an exception.
*
* The difference between stacking traits that extend BeforeAndAfterEach versus traits that implement withFixture is
* that setup and cleanup code happens before and after the test in BeforeAndAfterEach, but at the beginning and
* end of the test in withFixture. Thus if a withFixture method completes abruptly with an exception, it is
* considered a failed test. By contrast, if any of the beforeEach or afterEach methods of BeforeAndAfterEach
* complete abruptly, it is considered an aborted 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)
*
toString on each
* of the nested suites, separated by commas and surrounded by parentheses.
*
* @return a user-friendly string for this suite
*/
override def toString: String = Suite.suiteToString(None, this)
}