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/*
* Copyright 2001-2013 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 Suite.autoTagClassAnnotations
/**
* A suite of property-based tests.
*
*
* Recommended Usage:
* Class PropSpec is a good fit for teams that want to write tests exclusively in terms of property checks, and is also a good choice
* for writing the occasional test matrix when a different style trait is chosen as the main unit testing style.
*
*
* Here's an example PropSpec:
*
*
* package org.scalatest.examples.propspec
*
* import org.scalatest._
* import prop._
* import scala.collection.immutable._
*
* class SetSpec extends PropSpec with TableDrivenPropertyChecks with ShouldMatchers {
*
* val examples =
* Table(
* "set",
* BitSet.empty,
* HashSet.empty[Int],
* TreeSet.empty[Int]
* )
*
* property("an empty Set should have size 0") {
* forAll(examples) { set =>
* set.size should be (0)
* }
* }
*
* property("invoking head on an empty set should produce NoSuchElementException") {
* forAll(examples) { set =>
* evaluating { set.head } should produce [NoSuchElementException]
* }
* }
* }
*
*
*
* You can run a PropSpec by invoking execute on it.
* This method, which prints test results to the standard output, is intended to serve as a
* convenient way to run tests from within the Scala interpreter. For example,
* to run SetSpec from within the Scala interpreter, you could write:
*
*
*
* scala> new SetSpec execute
*
*
*
* And you would see:
*
*
*
* SetSpec:
* - an empty Set should have size 0
* - invoking head on an empty Set should produce NoSuchElementException
*
*
*
* Or, to run just the “an empty Set should have size 0” method, you could pass that test's name, or any unique substring of the
* name, such as "size 0" or even just "0". Here's an example:
*
*
*
* scala> new SetSpec execute "size 0"
* SetSpec:
* - an empty Set should have size 0
*
*
*
* 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.
*
*
*
* “property” is a method, defined in PropSpec, which will be invoked
* by the primary constructor of SetSpec. You specify the name of the test as
* a string between the parentheses, and the test code itself between curly braces.
* The test code is a function passed as a by-name parameter to property, which registers
* it for later execution.
*
*
*
* A PropSpec'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 with the property method while the PropSpec is
* in its registration phase. Any attempt to register a test after the PropSpec has
* entered its ready phase, i.e., after run has been invoked on the PropSpec,
* will be met with a thrown TestRegistrationClosedException. The recommended style
* of using PropSpec 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, PropSpec provides registration
* methods that start with ignore instead of property. Here's an example:
*
*
*
* package org.scalatest.examples.suite.ignore
*
* import org.scalatest._
* import prop._
* import scala.collection.immutable._
*
* class SetSpec extends PropSpec with TableDrivenPropertyChecks with ShouldMatchers {
*
* val examples =
* Table(
* "set",
* BitSet.empty,
* HashSet.empty[Int],
* TreeSet.empty[Int]
* )
*
* ignore("an empty Set should have size 0") {
* forAll(examples) { set =>
* set.size should be (0)
* }
* }
*
* property("invoking head on an empty set should produce NoSuchElementException") {
* forAll(examples) { set =>
* evaluating { set.head } should produce [NoSuchElementException]
* }
* }
* }
*
*
*
* If you run this version of SetSuite with:
*
*
*
* scala> new SetSpec execute
*
*
*
* It will run only the second test and report that the first test was ignored:
*
*
*
* SetSuite:
* - an empty Set should have size 0 !!! IGNORED !!!
* - invoking head on an empty Set should produce NoSuchElementException
*
*
* Informers
*
*
* One of the parameters to PropSpec'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 PropSpec's methods will be sufficient, but
* occasionally you may wish to provide custom information to the Reporter from a test.
* For this purpose, an Informer that will forward information
* to the current Reporter is provided via the info parameterless method.
* You can pass the extra information to the Informer via its apply method.
* The Informer will then pass the information to the Reporter via an InfoProvided event.
* Here's an example that shows both a direct use as well as an indirect use through the methods
* of GivenWhenThen:
*
*
*
* package org.scalatest.examples.propspec.info
*
* import org.scalatest._
* import prop._
* import collection.mutable
*
* class SetSuite extends PropSpec with TableDrivenPropertyChecks with GivenWhenThen {
*
* val examples =
* Table(
* "set",
* mutable.BitSet.empty,
* mutable.HashSet.empty[Int],
* mutable.LinkedHashSet.empty[Int]
* )
*
* property("an element can be added to an empty mutable Set") {
*
* forAll(examples) { set =>
*
* info("----------------")
*
* Given("an empty mutable " + set.getClass.getSimpleName)
* assert(set.isEmpty)
*
* When("an element is added")
* set += 99
*
* Then("the Set should have size 1")
* assert(set.size === 1)
*
* And("the Set should contain the added element")
* assert(set.contains(99))
* }
* }
* }
*
*
*
* If you run this PropSpec from the interpreter, you will see the following output:
*
*
* scala> new SetSuite execute
* SetSuite:
* - an element can be added to an empty mutable Set
* + ----------------
* + Given an empty mutable BitSet
* + When an element is added
* + Then the Set should have size 1
* + And the Set should contain the added element
* + ----------------
* + Given an empty mutable HashSet
* + When an element is added
* + Then the Set should have size 1
* + And the Set should contain the added element
* + ----------------
* + Given an empty mutable LinkedHashSet
* + When an element is added
* + Then the Set should have size 1
* + And the Set should contain the added element
*
*
* 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 pending in PropSpec like this:
*
*
*
* import org.scalatest._
* import prop._
* import scala.collection.immutable._
*
* class SetSpec extends PropSpec with TableDrivenPropertyChecks with ShouldMatchers {
*
* val examples =
* Table(
* "set",
* BitSet.empty,
* HashSet.empty[Int],
* TreeSet.empty[Int]
* )
*
* property("an empty Set should have size 0") (pending)
*
* property("invoking head on an empty set should produce NoSuchElementException") {
* forAll(examples) { set =>
* evaluating { set.head } should produce [NoSuchElementException]
* }
* }
* }
*
*
*
* (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 SetSuite with:
*
*
*
* scala> new SetSuite execute
*
*
*
* It will run both tests, but report that first test is pending. You'll see:
*
*
*
* SetSuite:
* - An empty Set should have size 0 (pending)
* - Invoking head on an empty Set should produce NoSuchElementException
*
*
*
* 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.
*
*
* Tagging tests
*
*
* A PropSpec's tests may be classified into groups by tagging them with string names.
* As with any suite, when executing a PropSpec, groups of tests can
* optionally be included and/or excluded. To tag a PropSpec'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 PropSpecs like this:
*
*
*
* package org.scalatest.examples.propspec.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 PropSpec tests into groups like this:
*
*
*
* import org.scalatest._
* import prop._
* import scala.collection.immutable._
*
* class SetSpec extends PropSpec with TableDrivenPropertyChecks with ShouldMatchers {
*
* val examples =
* Table(
* "set",
* BitSet.empty,
* HashSet.empty[Int],
* TreeSet.empty[Int]
* )
*
* property("an empty Set should have size 0", SlowTest) {
* forAll(examples) { set =>
* set.size should be (0)
* }
* }
*
* property("invoking head on an empty set should produce NoSuchElementException",
* SlowTest, DbTest) {
*
* forAll(examples) { set =>
* evaluating { set.head } should produce [NoSuchElementException]
* }
* }
* }
*
*
*
* 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.
*
*
* 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 techniques in “PropSpec” are identical to those in FunSuite, but with test
* replaced by “property”. The following table summarizes the options with a link to the relevant
* documentation for trait FunSuite:
*
*
*
* 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.
*
*
* Using PropSpec to implement a test matrix
*
*
* Using fixture-context objects in a PropSpec is a good way to implement a test matrix.
* What is the matrix? A test matrix is a series of tests that you need to run on a series of subjects. For example, The Scala API contains
* many implementations of trait Set. Every implementation must obey the contract of Set.
* One property of any Set is that an empty Set should have size 0, another is that
* invoking head on an empty Set should give you a NoSuchElementException, and so on. Already you have a matrix,
* where rows are the properties and the columns are the set implementations:
*
*
*
* BitSetHashSetTreeSetAn empty Set should have size 0 pass pass pass Invoking head on an empty set should produce NoSuchElementException pass pass pass
*
*
* One way to implement this test matrix is to define a trait to represent the columns (in this case, BitSet, HashSet,
* and TreeSet) as elements in a single-dimensional Table. Each element in the Table represents
* one Set implementation. Because different properties may require different fixture instances for those implementations, you
* can define a trait to hold the examples, like this:
*
*
* trait SetExamples extends Tables {
*
* def examples = Table("set", bitSet, hashSet, treeSet)
*
* def bitSet: BitSet
* def hashSet: HashSet[Int]
* def treeSet: TreeSet[Int]
* }
*
*
*
* Given this trait, you could provide empty sets in one implementation of SetExamples, and non-empty sets in another.
* Here's how you might provide empty set examples:
*
*
*
* class EmptySetExamples extends SetExamples {
* def bitSet = BitSet.empty
* def hashSet = HashSet.empty[Int]
* def treeSet = TreeSet.empty[Int]
* }
*
*
*
* And here's how you might provide set examples with one item each:
*
*
*
* class SetWithOneItemExamples extends SetExamples {
* def bitSet = BitSet(1)
* def hashSet = HashSet(1)
* def treeSet = TreeSet(1)
* }
*
*
*
* Armed with these example classes, you can define checks of properties that require
* empty or non-empty set fixtures by using instances of these classes as fixture-context
* objects. In other words, the columns of the test matrix are implemented as elements of
* a one-dimensional table of fixtures, the rows are implemented as property
* clauses of a PropSpec.
*
*
*
* Here's a complete example that checks the two properties mentioned previously:
*
*
*
* package org.scalatest.examples.propspec.matrix
*
* import org.scalatest._
* import org.scalatest.prop._
* import scala.collection.immutable._
*
* trait SetExamples extends Tables {
*
* def examples = Table("set", bitSet, hashSet, treeSet)
*
* def bitSet: BitSet
* def hashSet: HashSet[Int]
* def treeSet: TreeSet[Int]
* }
*
* class EmptySetExamples extends SetExamples {
* def bitSet = BitSet.empty
* def hashSet = HashSet.empty[Int]
* def treeSet = TreeSet.empty[Int]
* }
*
* class SetSpec extends PropSpec with TableDrivenPropertyChecks with ShouldMatchers {
*
* property("an empty Set should have size 0") {
* new EmptySetExamples {
* forAll(examples) { set =>
* set.size should be (0)
* }
* }
* }
*
* property("invoking head on an empty set should produce NoSuchElementException") {
* new EmptySetExamples {
* forAll(examples) { set =>
* evaluating { set.head } should produce [NoSuchElementException]
* }
* }
* }
* }
*
*
*
* One benefit of this approach is that the compiler will help you when you need to add either a new row
* or column to the matrix. In either case, you'll need to ensure all cells are checked to get your code to compile.
*
*
* Shared tests
*
*
* Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared"
* by different fixture objects.
* You accomplish this in a PropSpec in the same way you would do it in a FunSuite, exception instead of test
* you say property, and instead of testsFor you say propertiesFor.
* For more information, see the Shared tests section of FunSuite's
* documentation.
*
*
* @author Bill Venners
*/
@Finders(Array("org.scalatest.finders.PropSpecFinder"))
class PropSpec extends PropSpecLike {
/**
* Returns a user friendly string for this suite, composed of the
* simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite
* contains nested suites, the result of invoking 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)
}