ScalaTest 1.0
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org/scalatest/FeatureSpec.scala
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trait
FeatureSpec
extends
SuiteFeatureSpec
is intended for writing tests that are "higher level" than unit tests, for example, integration
tests, functional tests, and acceptance tests. You can use FeatureSpec
for unit testing if you prefer, however.
Here's an example:
import org.scalatest.FeatureSpec import org.scalatest.GivenWhenThen import scala.collection.mutable.Stack class StackFeatureSpec extends FeatureSpec with GivenWhenThen { feature("The user can pop an element off the top of the stack") { info("As a programmer") info("I want to be able to pop items off the stack") info("So that I can get them in last-in-first-out order") scenario("pop is invoked on a non-empty stack") { given("a non-empty stack") val stack = new Stack[Int] stack.push(1) stack.push(2) val oldSize = stack.size when("when pop is invoked on the stack") val result = stack.pop() then("the most recently pushed element should be returned") assert(result === 2) and("the stack should have one less item than before") assert(stack.size === oldSize - 1) } scenario("pop is invoked on an empty stack") { given("an empty stack") val emptyStack = new Stack[String] when("when pop is invoked on the stack") then("NoSuchElementException should be thrown") intercept[NoSuchElementException] { emptyStack.pop() } and("the stack should still be empty") assert(emptyStack.isEmpty) } } }
A FeatureSpec
contains feature clauses and scenarios. You define a feature clause
with feature
, and a scenario with scenario
. Both
feature
and scenario
are methods, defined in
FeatureSpec
, which will be invoked
by the primary constructor of StackFeatureSpec
.
A feature clause describes a feature of the subject (class or other entity) you are specifying
and testing. In the previous example,
the subject under specification and test is a stack. The feature being specified and tested is
the ability for a user (a programmer in this case) to pop an element off the top of the stack. With each scenario you provide a
string (the spec text) that specifies the behavior of the subject for
one scenario in which the feature may be used, and a block of code that tests that behavior.
You place the spec text between the parentheses, followed by the test code between curly
braces. The test code will be wrapped up as a function passed as a by-name parameter to
scenario
, which will register the test for later execution.
A FeatureSpec
's lifecycle has two phases: the registration phase and the
ready phase. It starts in registration phase and enters ready phase the first time
run
is called on it. It then remains in ready phase for the remainder of its lifetime.
Scenarios can only be registered with the scenario
method while the FeatureSpec
is
in its registration phase. Any attempt to register a scenario after the FeatureSpec
has
entered its ready phase, i.e., after run
has been invoked on the FeatureSpec
,
will be met with a thrown TestRegistrationClosedException
. The recommended style
of using FeatureSpec
is to register tests during object construction as is done in all
the examples shown here. If you keep to the recommended style, you should never see a
TestRegistrationClosedException
.
Each scenario represents one test. The name of the test is the spec text passed to the scenario
method.
The feature name does not appear as part of the test name. In a FeatureSpec
, therefore, you must take care
to ensure that each test has a unique name (in other words, that each scenario
has unique spec text).
When you run a FeatureSpec
, it will send Formatter
s in the events it sends to the
Reporter
. ScalaTest's built-in reporters will report these events in such a way
that the output is easy to read as an informal specification of the subject being tested.
For example, if you ran StackFeatureSpec
from within the Scala interpreter:
scala> (new StackFeatureSpec).execute()
You would see:
Feature: The user can pop an element off the top of the stack As a programmer I want to be able to pop items off the stack So that I can get them in last-in-first-out order Scenario: pop is invoked on a non-empty stack Given a non-empty stack When when pop is invoked on the stack Then the most recently pushed element should be returned And the stack should have one less item than before Scenario: pop is invoked on an empty stack Given an empty stack When when pop is invoked on the stack Then NoSuchElementException should be thrown And the stack should still be empty
Shared fixtures
A test fixture is objects or other artifacts (such as files, sockets, database
connections, etc.) used by tests to do their work. You can use fixtures in
FeatureSpec
s with the same approaches suggested for Suite
in
its documentation. The same text that appears in the test fixture
section of Suite
's documentation is repeated here, with examples changed from
Suite
to FeatureSpec
.
If a fixture is used by only one test, then the definitions of the fixture objects can
be local to the test function, such as the objects assigned to stack
and emptyStack
in the
previous StackFeatureSpec
examples. If multiple tests need to share a fixture, the best approach
is to assign them to instance variables. Here's a (very contrived) example, in which the object assigned
to shared
is used by multiple test functions:
import org.scalatest.FeatureSpec class ArithmeticFeatureSpec extends FeatureSpec { // Sharing immutable fixture objects via instance variables val shared = 5 feature("Integer arithmetic") { scenario("addition") { val sum = 2 + 3 assert(sum === shared) } scenario("subtraction") { val diff = 7 - 2 assert(diff === shared) } } }
In some cases, however, shared mutable fixture objects may be changed by tests such that
they need to be recreated or reinitialized before each test. Shared resources such
as files or database connections may also need to be created and initialized before,
and cleaned up after, each test. JUnit offers methods setUp
and
tearDown
for this purpose. In ScalaTest, you can use the BeforeAndAfterEach
trait,
which will be described later, to implement an approach similar to JUnit's setUp
and tearDown
, however, this approach often involves reassigning var
s
between tests. Before going that route, you should consider some approaches that
avoid var
s. One approach is to write one or more create-fixture methods
that return a new instance of a needed object (or a tuple or case class holding new instances of
multiple objects) each time it is called. You can then call a create-fixture method at the beginning of each
test that needs the fixture, storing the fixture object or objects in local variables. Here's an example:
import org.scalatest.FeatureSpec import scala.collection.mutable.ListBuffer class MyFeatureSpec extends FeatureSpec { // create objects needed by tests and return as a tuple def createFixture = ( new StringBuilder("ScalaTest is "), new ListBuffer[String] ) feature("The create-fixture approach") { scenario("shared fixture objects are mutated by a test") { val (builder, lbuf) = createFixture builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(lbuf.isEmpty) lbuf += "sweet" } scenario("test gets a fresh copy of the shared fixture") { val (builder, lbuf) = createFixture builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(lbuf.isEmpty) } } }
If different tests in the same FeatureSpec
require different fixtures, you can create multiple create-fixture methods and
call the method (or methods) needed by each test at the begining of the test. If every test requires the same set of
mutable fixture objects, one other approach you can take is make them simply val
s and mix in trait
OneInstancePerTest
. If you mix in OneInstancePerTest
, each test
will be run in its own instance of the FeatureSpec
, similar to the way JUnit tests are executed.
Although the create-fixture and OneInstancePerTest
approaches take care of setting up a fixture before each
test, they don't address the problem of cleaning up a fixture after the test completes. In this situation,
one option is to mix in the BeforeAndAfterEach
trait.
BeforeAndAfterEach
's beforeEach
method will be run before, and its afterEach
method after, each test (like JUnit's setUp
and tearDown
methods, respectively).
For example, you could create a temporary file before each test, and delete it afterwords, like this:
import org.scalatest.FeatureSpec import org.scalatest.BeforeAndAfterEach import java.io.FileReader import java.io.FileWriter import java.io.File class FileIoFeatureSpec extends FeatureSpec with BeforeAndAfterEach { private val FileName = "TempFile.txt" private var reader: FileReader = _ // Set up the temp file needed by the test override def beforeEach() { val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test reader = new FileReader(FileName) } // Close and delete the temp file override def afterEach() { reader.close() val file = new File(FileName) file.delete() } feature("Reading and writing files") { scenario("reading from a temp file") { var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } scenario("reading first char of a temp file") { assert(reader.read() === 'H') } scenario("no fixture is passed") { assert(1 + 1 === 2) } } }
In this example, the instance variable reader
is a var
, so
it can be reinitialized between tests by the beforeEach
method.
Although the BeforeAndAfterEach
approach should be familiar to the users of most
test other frameworks, ScalaTest provides another alternative that also allows you to perform cleanup
after each test: overriding withFixture(NoArgTest)
.
To execute each test, Suite
's implementation of the runTest
method wraps an invocation
of the appropriate test method in a no-arg function. runTest
passes that test function to the withFixture(NoArgTest)
method, which is responsible for actually running the test by invoking the function. Suite
's
implementation of withFixture(NoArgTest)
simply invokes the function, like this:
// Default implementation protected def withFixture(test: NoArgTest) { test() }
The withFixture(NoArgTest)
method exists so that you can override it and set a fixture up before, and clean it up after, each test.
Thus, the previous temp file example could also be implemented without mixing in BeforeAndAfterEach
, like this:
import org.scalatest.FeatureSpec import org.scalatest.BeforeAndAfterEach import java.io.FileReader import java.io.FileWriter import java.io.File class FileIoFeatureSpec extends FeatureSpec { private var reader: FileReader = _ override def withFixture(test: NoArgTest) { val FileName = "TempFile.txt" // Set up the temp file needed by the test val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test reader = new FileReader(FileName) try { test() // Invoke the test function } finally { // Close and delete the temp file reader.close() val file = new File(FileName) file.delete() } } feature("Reading and writing files") { scenario("reading from a temp file") { var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } scenario("reading first char of a temp file") { assert(reader.read() === 'H') } scenario("no fixture is passed") { assert(1 + 1 === 2) } } }
If you prefer to keep your test classes immutable, one final variation is to use the
FixtureFeatureSpec
trait from the
org.scalatest.fixture
package. Tests in an org.scalatest.fixture.FixtureFeatureSpec
can have a fixture
object passed in as a parameter. You must indicate the type of the fixture object
by defining the Fixture
type member and define a withFixture
method that takes a one-arg test function.
(A FixtureFeatureSpec
has two overloaded withFixture
methods, therefore, one that takes a OneArgTest
and the other, inherited from Suite
, that takes a NoArgTest
.)
Inside the withFixture(OneArgTest)
method, you create the fixture, pass it into the test function, then perform any
necessary cleanup after the test function returns. Instead of invoking each test directly, a FixtureFeatureSpec
will
pass a function that invokes the code of a test to withFixture(OneArgTest)
. Your withFixture(OneArgTest)
method, therefore,
is responsible for actually running the code of the test by invoking the test function.
For example, you could pass the temp file reader fixture to each test that needs it
by overriding the withFixture(OneArgTest)
method of a FixtureFeatureSpec
, like this:
import org.scalatest.fixture.FixtureFeatureSpec import java.io.FileReader import java.io.FileWriter import java.io.File class MySuite extends FixtureFeatureSpec { type FixtureParam = FileReader def withFixture(test: OneArgTest) { val FileName = "TempFile.txt" // Set up the temp file needed by the test val writer = new FileWriter(FileName) try { writer.write("Hello, test!") } finally { writer.close() } // Create the reader needed by the test val reader = new FileReader(FileName) try { // Run the test using the temp file test(reader) } finally { // Close and delete the temp file reader.close() val file = new File(FileName) file.delete() } } feature("Reading and writing files") { scenario("reading from a temp file") { reader => var builder = new StringBuilder var c = reader.read() while (c != -1) { builder.append(c.toChar) c = reader.read() } assert(builder.toString === "Hello, test!") } scenario("reading first char of a temp file") { reader => assert(reader.read() === 'H') } scenario("no fixture is passed") { () => assert(1 + 1 === 2) } } }
It is worth noting that the only difference in the test code between the mutable
BeforeAndAfterEach
approach shown here and the immutable FixtureFeatureSpec
approach shown previously is that two of the FixtureFeatureSpec
's test functions take a FileReader
as
a parameter via the "reader =>
" at the beginning of the function. Otherwise the test code is identical.
One benefit of the explicit parameter is that, as demonstrated
by the "no fixture passed
" scenario, a FixtureFeatureSpec
test need not take the fixture. So you can have some tests that take a fixture, and others that don't.
In this case, the FixtureFeatureSpec
provides documentation indicating which
tests use the fixture and which don't, whereas the BeforeAndAfterEach
approach does not.
(If you have want to combine tests that take different fixture types in the same FeatureSpec
, you can
use MultipleFixtureFeatureSpec.)
If you want to execute code before and after all tests (and nested suites) in a suite, such
as you could do with @BeforeClass
and @AfterClass
annotations in JUnit 4, you can use the beforeAll
and afterAll
methods of BeforeAndAfterAll
. See the documentation for BeforeAndAfterAll
for
an example.
Sometimes you may want to run the same test code on different fixture objects. In other words, you may want to write tests that are "shared"
by different fixture objects.
To accomplish this in a FeatureSpec
, you first place shared tests (i.e., shared scenarios) in
behavior functions. These behavior functions will be
invoked during the construction phase of any FeatureSpec
that uses them, so that the scenarios they contain will
be registered as scenarios in that FeatureSpec
.
For example, given this stack class:
import scala.collection.mutable.ListBuffer class Stack[T] { val MAX = 10 private var buf = new ListBuffer[T] def push(o: T) { if (!full) o +: buf else throw new IllegalStateException("can't push onto a full stack") } def pop(): T = { if (!empty) buf.remove(0) else throw new IllegalStateException("can't pop an empty stack") } def peek: T = { if (!empty) buf(0) else throw new IllegalStateException("can't pop an empty stack") } def full: Boolean = buf.size == MAX def empty: Boolean = buf.size == 0 def size = buf.size override def toString = buf.mkString("Stack(", ", ", ")") }
You may want to test the Stack
class in different states: empty, full, with one item, with one item less than capacity,
etc. You may find you have several scenarios that make sense any time the stack is non-empty. Thus you'd ideally want to run
those same scenarios for three stack fixture objects: a full stack, a stack with a one item, and a stack with one item less than
capacity. With shared tests, you can factor these scenarios out into a behavior function, into which you pass the
stack fixture to use when running the tests. So in your FeatureSpec
for stack, you'd invoke the
behavior function three times, passing in each of the three stack fixtures so that the shared scenarios are run for all three fixtures.
You can define a behavior function that encapsulates these shared scenarios inside the FeatureSpec
that uses them. If they are shared
between different FeatureSpec
s, however, you could also define them in a separate trait that is mixed into
each FeatureSpec
that uses them.
For example, here the nonEmptyStack
behavior function (in this case, a
behavior method) is defined in a trait along with another
method containing shared scenarios for non-full stacks:
import org.scalatest.FeatureSpec import org.scalatest.GivenWhenThen import org.scalatestexamples.helpers.Stack trait FeatureSpecStackBehaviors { this: FeatureSpec with GivenWhenThen => def nonEmptyStack(createNonEmptyStack: => Stack[Int], lastItemAdded: Int) { scenario("empty is invoked on this non-empty stack: " + createNonEmptyStack.toString) { given("a non-empty stack") val stack = createNonEmptyStack when("empty is invoked on the stack") then("empty returns false") assert(!stack.empty) } scenario("peek is invoked on this non-empty stack: " + createNonEmptyStack.toString) { given("a non-empty stack") val stack = createNonEmptyStack val size = stack.size when("peek is invoked on the stack") then("peek returns the last item added") assert(stack.peek === lastItemAdded) and("the size of the stack is the same as before") assert(stack.size === size) } scenario("pop is invoked on this non-empty stack: " + createNonEmptyStack.toString) { given("a non-empty stack") val stack = createNonEmptyStack val size = stack.size when("pop is invoked on the stack") then("pop returns the last item added") assert(stack.pop === lastItemAdded) and("the size of the stack one less than before") assert(stack.size === size - 1) } } def nonFullStack(createNonFullStack: => Stack[Int]) { scenario("full is invoked on this non-full stack: " + createNonFullStack.toString) { given("a non-full stack") val stack = createNonFullStack when("full is invoked on the stack") then("full returns false") assert(!stack.full) } scenario("push is invoked on this non-full stack: " + createNonFullStack.toString) { given("a non-full stack") val stack = createNonFullStack val size = stack.size when("push is invoked on the stack") stack.push(7) then("the size of the stack is one greater than before") assert(stack.size === size + 1) and("the top of the stack contains the pushed value") assert(stack.peek === 7) } } }
Given these behavior functions, you could invoke them directly, but FeatureSpec
offers a DSL for the purpose,
which looks like this:
scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed)) scenariosFor(nonFullStack(stackWithOneItem))
If you prefer to use an imperative style to change fixtures, for example by mixing in BeforeAndAfterEach
and
reassigning a stack
var
in beforeEach
, you could write your behavior functions
in the context of that var
, which means you wouldn't need to pass in the stack fixture because it would be
in scope already inside the behavior function. In that case, your code would look like this:
scenariosFor(nonEmptyStack) // assuming lastValuePushed is also in scope inside nonEmptyStack scenariosFor(nonFullStack)
The recommended style, however, is the functional, pass-all-the-needed-values-in style. Here's an example:
import org.scalatest.FeatureSpec import org.scalatest.GivenWhenThen import org.scalatestexamples.helpers.Stack class StackFeatureSpec extends FeatureSpec with GivenWhenThen with FeatureSpecStackBehaviors { // Stack fixture creation methods def emptyStack = new Stack[Int] def fullStack = { val stack = new Stack[Int] for (i <- 0 until stack.MAX) stack.push(i) stack } def stackWithOneItem = { val stack = new Stack[Int] stack.push(9) stack } def stackWithOneItemLessThanCapacity = { val stack = new Stack[Int] for (i <- 1 to 9) stack.push(i) stack } val lastValuePushed = 9 feature("A Stack is pushed and popped") { scenario("empty is invoked on an empty stack") { given("an empty stack") val stack = emptyStack when("empty is invoked on the stack") then("empty returns true") assert(stack.empty) } scenario("peek is invoked on an empty stack") { given("an empty stack") val stack = emptyStack when("peek is invoked on the stack") then("peek throws IllegalStateException") intercept[IllegalStateException] { stack.peek } } scenario("pop is invoked on an empty stack") { given("an empty stack") val stack = emptyStack when("pop is invoked on the stack") then("pop throws IllegalStateException") intercept[IllegalStateException] { emptyStack.pop } } scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed)) scenariosFor(nonFullStack(stackWithOneItem)) scenariosFor(nonEmptyStack(stackWithOneItemLessThanCapacity, lastValuePushed)) scenariosFor(nonFullStack(stackWithOneItemLessThanCapacity)) scenario("full is invoked on a full stack") { given("an full stack") val stack = fullStack when("full is invoked on the stack") then("full returns true") assert(stack.full) } scenariosFor(nonEmptyStack(fullStack, lastValuePushed)) scenario("push is invoked on a full stack") { given("an full stack") val stack = fullStack when("push is invoked on the stack") then("push throws IllegalStateException") intercept[IllegalStateException] { stack.push(10) } } } }
If you load these classes into the Scala interpreter (with scalatest's JAR file on the class path), and execute it, you'll see:
scala> (new StackFeatureSpec).execute() Feature: A Stack is pushed and popped Scenario: empty is invoked on an empty stack Given an empty stack When empty is invoked on the stack Then empty returns true Scenario: peek is invoked on an empty stack Given an empty stack When peek is invoked on the stack Then peek throws IllegalStateException Scenario: pop is invoked on an empty stack Given an empty stack When pop is invoked on the stack Then pop throws IllegalStateException Scenario: empty is invoked on this non-empty stack: Stack(9) Given a non-empty stack When empty is invoked on the stack Then empty returns false Scenario: peek is invoked on this non-empty stack: Stack(9) Given a non-empty stack When peek is invoked on the stack Then peek returns the last item added And the size of the stack is the same as before Scenario: pop is invoked on this non-empty stack: Stack(9) Given a non-empty stack When pop is invoked on the stack Then pop returns the last item added And the size of the stack one less than before Scenario: full is invoked on this non-full stack: Stack(9) Given a non-full stack When full is invoked on the stack Then full returns false Scenario: push is invoked on this non-full stack: Stack(9) Given a non-full stack When push is invoked on the stack Then the size of the stack is one greater than before And the top of the stack contains the pushed value Scenario: empty is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1) Given a non-empty stack When empty is invoked on the stack Then empty returns false Scenario: peek is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1) Given a non-empty stack When peek is invoked on the stack Then peek returns the last item added And the size of the stack is the same as before Scenario: pop is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1) Given a non-empty stack When pop is invoked on the stack Then pop returns the last item added And the size of the stack one less than before Scenario: full is invoked on this non-full stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1) Given a non-full stack When full is invoked on the stack Then full returns false Scenario: push is invoked on this non-full stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1) Given a non-full stack When push is invoked on the stack Then the size of the stack is one greater than before And the top of the stack contains the pushed value Scenario: full is invoked on a full stack Given an full stack When full is invoked on the stack Then full returns true Scenario: empty is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0) Given a non-empty stack When empty is invoked on the stack Then empty returns false Scenario: peek is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0) Given a non-empty stack When peek is invoked on the stack Then peek returns the last item added And the size of the stack is the same as before Scenario: pop is invoked on this non-empty stack: Stack(9, 8, 7, 6, 5, 4, 3, 2, 1, 0) Given a non-empty stack When pop is invoked on the stack Then pop returns the last item added And the size of the stack one less than before Scenario: push is invoked on a full stack Given an full stack When push is invoked on the stack Then push throws IllegalStateException
One thing to keep in mind when using shared tests is that in ScalaTest, each test in a suite must have a unique name.
If you register the same tests repeatedly in the same suite, one problem you may encounter is an exception at runtime
complaining that multiple tests are being registered with the same test name.
In a FeatureSpec
there is no nesting construct analogous to Spec
's describe
clause.
Therefore, you need to do a bit of
extra work to ensure that the test names are unique. If a duplicate test name problem shows up in a
FeatureSpec
, you'll need to pass in a prefix or suffix string to add to each test name. You can pass this string
the same way you pass any other data needed by the shared tests, or just call toString
on the shared fixture object.
This is the approach taken by the previous FeatureSpecStackBehaviors
example.
Given this FeatureSpecStackBehaviors
trait, calling it with the stackWithOneItem
fixture, like this:
scenariosFor(nonEmptyStack(stackWithOneItem, lastValuePushed))
yields test names:
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)
Tagging tests
A FeatureSpec
's tests may be classified into groups by tagging them with string names.
As with any suite, when executing a FeatureSpec
, groups of tests can
optionally be included and/or excluded. To tag a FeatureSpec
's tests,
you pass objects that extend abstract class org.scalatest.Tag
to methods
that register tests, test
and ignore
. Class Tag
takes one parameter, a string name. If you have
created Java annotation interfaces for use as group names in direct subclasses of org.scalatest.Suite
,
then you will probably want to use group names on your FeatureSpec
s that match. To do so, simply
pass the fully qualified names of the Java interfaces to the Tag
constructor. For example, if you've
defined Java annotation interfaces with fully qualified names, com.mycompany.groups.SlowTest
and
com.mycompany.groups.DbTest
, then you could
create matching groups for FeatureSpec
s like this:
import org.scalatest.Tag object SlowTest extends Tag("com.mycompany.groups.SlowTest") object DbTest extends Tag("com.mycompany.groups.DbTest")
Given these definitions, you could place FeatureSpec
tests into groups like this:
import org.scalatest.FeatureSpec class ArithmeticFeatureSpec extends FeatureSpec { // Sharing fixture objects via instance variables val shared = 5 feature("Integer arithmetic") { scenario("addition", SlowTest) { val sum = 2 + 3 assert(sum === shared) } scenario("subtraction", SlowTest, DbTest) { val diff = 7 - 2 assert(diff === shared) } } }
This code marks both tests, "addition" and "subtraction," with the com.mycompany.groups.SlowTest
tag,
and test "subtraction" with the com.mycompany.groups.DbTest
tag.
The primary run
method takes a Filter
, whose constructor takes an optional
Set[String]
s called tagsToInclude
and a Set[String]
called
tagsToExclude
. If tagsToInclude
is None
, all tests will be run
except those those belonging to tags listed in the
tagsToExclude
Set
. If tagsToInclude
is defined, only tests
belonging to tags mentioned in the tagsToInclude
set, and not mentioned in tagsToExclude
,
will be run.
Ignored tests
To support the common use case of “temporarily” disabling a test, with the
good intention of resurrecting the test at a later time, FeatureSpec
provides registration
methods that start with ignore
instead of scenario
. For example, to temporarily
disable the test named addition
, just change “scenario
” into “ignore
,” like this:
import org.scalatest.FeatureSpec class ArithmeticFeatureSpec extends FeatureSpec { // Sharing fixture objects via instance variables val shared = 5 feature("Integer arithmetic") { ignore("addition") { val sum = 2 + 3 assert(sum === shared) } scenario("subtraction") { val diff = 7 - 2 assert(diff === shared) } } }
If you run this version of ArithmeticFeatureSpec
with:
scala> (new ArithmeticFeatureSpec).execute()
It will run only subtraction
and report that addition
was ignored:
Feature: Integer arithmetic Scenario: addition !!! IGNORED !!! Scenario: subtraction
Informers
One of the parameters to the primary run
method is a Reporter
, which
will collect and report information about the running suite of tests.
Information about suites and tests that were run, whether tests succeeded or failed,
and tests that were ignored will be passed to the Reporter
as the suite runs.
Most often the reporting done by default by FeatureSpec
's methods will be sufficient, but
occasionally you may wish to provide custom information to the Reporter
from a test.
For this purpose, an Informer
that will forward information to the current Reporter
is provided via the info
parameterless method.
You can pass the extra information to the Informer
via its apply
method.
The Informer
will then pass the information to the Reporter
via an InfoProvided
event.
Here's an example:
import org.scalatest.FeatureSpec class ArithmeticFeatureSpec extends FeatureSpec { feature("Integer arithmetic") { scenario("addition") { val sum = 2 + 3 assert(sum === 5) info("Addition seems to work") } scenario("subtraction") { val diff = 7 - 2 assert(diff === 5) } } }If you run this
ArithmeticFeatureSpec
from the interpreter, you will see the following message
included in the printed report:
Feature: Integer arithmetic Scenario: addition Addition seems to work
One use case for the Informer
is to pass more information about a scenario to the reporter. For example,
the GivenWhenThen
trait provides methods that use the implicit info
provided by FeatureSpec
to pass such information to the reporter. Here's an example:
import org.scalatest.FeatureSpec import org.scalatest.GivenWhenThen class ArithmeticSpec extends FeatureSpec with GivenWhenThen { feature("Integer arithmetic") { scenario("addition") { given("two integers") val x = 2 val y = 3 when("they are added") val sum = x + y then("the result is the sum of the two numbers") assert(sum === 5) } scenario("subtraction") { given("two integers") val x = 7 val y = 2 when("one is subtracted from the other") val diff = x - y then("the result is the difference of the two numbers") assert(diff === 5) } } }
If you run this FeatureSpec
from the interpreter, you will see the following messages
included in the printed report:
scala> (new ArithmeticFeatureSpec).execute() Feature: Integer arithmetic Scenario: addition Given two integers When they are added Then the result is the sum of the two numbers Scenario: subtraction Given two integers When one is subtracted from the other Then the result is the difference of the two numbers
Pending tests
A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.
To support this style of testing, a test can be given a name that specifies one
bit of behavior required by the system being tested. The test can also include some code that
sends more information about the behavior to the reporter when the tests run. At the end of the test,
it can call method pending
, which will cause it to complete abruptly with TestPendingException
.
Because tests in ScalaTest can be designated as pending with TestPendingException
, both the test name and any information
sent to the reporter when running the test can appear in the report of a test run. (In other words,
the code of a pending test is executed just like any other test.) However, because the test completes abruptly
with TestPendingException
, the test will be reported as pending, to indicate
the actual test, and possibly the functionality, has not yet been implemented.
You can mark tests as pending in a FeatureSpec
like this:
import org.scalatest.FeatureSpec class ArithmeticFeatureSpec extends FeatureSpec { // Sharing fixture objects via instance variables val shared = 5 feature("Integer arithmetic") { scenario("addition") { val sum = 2 + 3 assert(sum === shared) } scenario("subtraction") (pending) } }
(Note: "(pending)
" is the body of the test. Thus the test contains just one statement, an invocation
of the pending
method, which throws TestPendingException
.)
If you run this version of ArithmeticFeatureSpec
with:
scala> (new ArithmeticFeatureSpec).execute()
It will run both tests, but report that subtraction
is pending. You'll see:
Feature: Integer arithmetic Scenario: addition Scenario: subtraction (pending)
One difference between an ignored test and a pending one is that an ignored test is intended to be used during a significant refactorings of the code under test, when tests break and you don't want to spend the time to fix all of them immediately. You can mark some of those broken tests as ignored temporarily, so that you can focus the red bar on just failing tests you actually want to fix immediately. Later you can go back and fix the ignored tests. In other words, by ignoring some failing tests temporarily, you can more easily notice failed tests that you actually want to fix. By contrast, a pending test is intended to be used before a test and/or the code under test is written. Pending indicates you've decided to write a test for a bit of behavior, but either you haven't written the test yet, or have only written part of it, or perhaps you've written the test but don't want to implement the behavior it tests until after you've implemented a different bit of behavior you realized you need first. Thus ignored tests are designed to facilitate refactoring of existing code whereas pending tests are designed to facilitate the creation of new code.
One other difference between ignored and pending tests is that ignored tests are implemented as a test tag that is
excluded by default. Thus an ignored test is never executed. By contrast, a pending test is implemented as a
test that throws TestPendingException
(which is what calling the pending
method does). Thus
the body of pending tests are executed up until they throw TestPendingException
. The reason for this difference
is that it enables your unfinished test to send InfoProvided
messages to the reporter before it completes
abruptly with TestPendingException
, as shown in the previous example on Informer
s
that used the GivenWhenThen
trait. For example, the following snippet in a FeatureSpec
:
feature("Integer arithmetic") { scenario("addition") { given("two integers") when("they are added") then("the result is the sum of the two numbers") pending } // ...
Would yield the following output when run in the interpreter:
Feature: Integer arithmetic Scenario: addition (pending) Given two integers When they are added Then the result is the sum of the two numbers
Method Summary | |
protected def
|
feature
(description : java.lang.String)(f : => Unit) : Unit
Describe a “subject” being specified and tested by the passed function value. The
passed function value may contain more describers (defined with
describe ) and/or tests
(defined with it ). This trait's implementation of this method will register the
description string and immediately invoke the passed function. |
protected def
|
ignore
(specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
Register a test to ignore, which has the given spec text, optional tags, and test function value that takes no arguments.
This method will register the test for later ignoring via an invocation of one of the
execute
methods. This method exists to make it easy to ignore an existing test by changing the call to it
to ignore without deleting or commenting out the actual test code. The test will not be executed, but a
report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames for an example.) The resulting test name must not have been registered previously on
this Spec instance. |
protected def
|
ignore
(specText : java.lang.String)(testFun : => Unit) : Unit
Register a test to ignore, which has the given spec text and test function value that takes no arguments.
This method will register the test for later ignoring via an invocation of one of the
execute
methods. This method exists to make it easy to ignore an existing test by changing the call to it
to ignore without deleting or commenting out the actual test code. The test will not be executed, but a
report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames for an example.) The resulting test name must not have been registered previously on
this Spec instance. |
protected implicit def
|
info
: Informer
Returns an
Informer that during test execution will forward strings (and other objects) passed to its
apply method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
FeatureSpec is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
throw an exception. This method can be called safely by any thread. |
override def
|
run
(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Runs this suite of tests.
|
protected override def
|
runTest
(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
Run a test. This trait's implementation runs the test registered with the name specified by
testName . Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documenation
for testNames for an example.) |
protected override def
|
runTests
(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
Run zero to many of this
FeatureSpec 's tests. |
protected def
|
scenario
(specText : java.lang.String)(testFun : => Unit) : Unit
Register a test with the given spec text and test function value that takes no arguments.
This method will register the test for later execution via an invocation of one of the
execute
methods. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames for an example.) The resulting test name must not have been registered previously on
this Spec instance. |
protected def
|
scenario
(specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
Register a test with the given spec text, optional tags, and test function value that takes no arguments.
An invocation of this method is called an “example.”
This method will register the test for later execution via an invocation of one of the
execute
methods. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames for an example.) The resulting test name must not have been registered previously on
this Spec instance. |
protected def
|
scenariosFor
(unit : Unit) : Unit
Registers shared scenarios.
|
override def
|
tags
: scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
A
Map whose keys are String tag names to which tests in this Spec belong, and values
the Set of test names that belong to each tag. If this FeatureSpec contains no tags, this method returns an empty Map . |
override def
|
testNames
: scala.collection.immutable.Set[java.lang.String]
An immutable
Set of test names. If this FeatureSpec contains no tests, this method returns an
empty Set . |
Methods inherited from Suite | |
nestedSuites, execute, execute, execute, execute, groups, withFixture, runNestedSuites, suiteName, pending, pendingUntilFixed, expectedTestCount |
Methods inherited from Assertions | |
assert, assert, assert, assert, convertToEqualizer, intercept, expect, expect, fail, fail, fail, fail |
Methods inherited from AnyRef | |
getClass, hashCode, equals, clone, toString, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized |
Methods inherited from Any | |
==, !=, isInstanceOf, asInstanceOf |
Method Details |
protected implicit
def
info : Informer
Informer
that during test execution will forward strings (and other objects) passed to its
apply
method to the current reporter. If invoked in a constructor, it
will register the passed string for forwarding later during test execution. If invoked while this
FeatureSpec
is being executed, such as from inside a test function, it will forward the information to
the current reporter immediately. If invoked at any other time, it will
throw an exception. This method can be called safely by any thread.protected
def
scenario(specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
execute
methods. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames
for an example.) The resulting test name must not have been registered previously on
this Spec
instance.specText -
the specification text, which will be combined with the descText of any surrounding describers to form the test nametestTags -
the optional list of tags for this testtestFun -
the test functionDuplicateTestNameException -
if a test with the same name has been registered previouslyTestRegistrationClosedException -
if invoked after run
has been invoked on this suiteNullPointerException -
if specText
or any passed test tag is null
protected
def
scenario(specText : java.lang.String)(testFun : => Unit) : Unit
execute
methods. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames
for an example.) The resulting test name must not have been registered previously on
this Spec
instance.specText -
the specification text, which will be combined with the descText of any surrounding describers to form the test nametestFun -
the test functionDuplicateTestNameException -
if a test with the same name has been registered previouslyTestRegistrationClosedException -
if invoked after run
has been invoked on this suiteNullPointerException -
if specText
or any passed test tag is null
protected
def
ignore(specText : java.lang.String, testTags : Tag*)(testFun : => Unit) : Unit
execute
methods. This method exists to make it easy to ignore an existing test by changing the call to it
to ignore
without deleting or commenting out the actual test code. The test will not be executed, but a
report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames
for an example.) The resulting test name must not have been registered previously on
this Spec
instance.specText -
the specification text, which will be combined with the descText of any surrounding describers to form the test nametestTags -
the optional list of tags for this testtestFun -
the test functionDuplicateTestNameException -
if a test with the same name has been registered previouslyTestRegistrationClosedException -
if invoked after run
has been invoked on this suiteNullPointerException -
if specText
or any passed test tag is null
protected
def
ignore(specText : java.lang.String)(testFun : => Unit) : Unit
execute
methods. This method exists to make it easy to ignore an existing test by changing the call to it
to ignore
without deleting or commenting out the actual test code. The test will not be executed, but a
report will be sent that indicates the test was ignored. The name of the test will be a concatenation of the text of all surrounding describers,
from outside in, and the passed spec text, with one space placed between each item. (See the documenation
for testNames
for an example.) The resulting test name must not have been registered previously on
this Spec
instance.specText -
the specification text, which will be combined with the descText of any surrounding describers to form the test nametestFun -
the test functionDuplicateTestNameException -
if a test with the same name has been registered previouslyTestRegistrationClosedException -
if invoked after run
has been invoked on this suiteNullPointerException -
if specText
or any passed test tag is null
protected
def
feature(description : java.lang.String)(f : => Unit) : Unit
describe
) and/or tests
(defined with it
). This trait's implementation of this method will register the
description string and immediately invoke the passed function.override
def
tags : scala.collection.immutable.Map[java.lang.String, scala.collection.immutable.Set[java.lang.String]]
Map
whose keys are String
tag names to which tests in this Spec
belong, and values
the Set
of test names that belong to each tag. If this FeatureSpec
contains no tags, this method returns an empty Map
.
This trait's implementation returns tags that were passed as strings contained in Tag
objects passed to
methods test
and ignore
.
protected override
def
runTest(testName : java.lang.String, reporter : Reporter, stopper : Stopper, configMap : scala.collection.immutable.Map[java.lang.String, Any], tracker : Tracker) : Unit
testName
. Each test's name is a concatenation of the text of all describers surrounding a test,
from outside in, and the test's spec text, with one space placed between each item. (See the documenation
for testNames
for an example.)testName -
the name of one test to execute.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.configMap -
a Map
of properties that can be used by this Spec
's executing tests.NullPointerException -
if any of testName
, reporter
, stopper
, or configMap
is null
.protected override
def
runTests(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
FeatureSpec
's tests.
This method takes a testName
parameter that optionally specifies a test to invoke.
If testName
is Some
, this trait's implementation of this method
invokes runTest
on this object, passing in:
testName
- the String
value of the testName
Option
passed
to this methodreporter
- the Reporter
passed to this method, or one that wraps and delegates to itstopper
- the Stopper
passed to this method, or one that wraps and delegates to itconfigMap
- the configMap
passed to this method, or one that wraps and delegates to it
This method takes a Set
of tag names that should be included (tagsToInclude
), and a Set
that should be excluded (tagsToExclude
), when deciding which of this Suite
's tests to execute.
If tagsToInclude
is empty, all tests will be executed
except those those belonging to tags listed in the tagsToExclude
Set
. If tagsToInclude
is non-empty, only tests
belonging to tags mentioned in tagsToInclude
, and not mentioned in tagsToExclude
will be executed. However, if testName
is Some
, tagsToInclude
and tagsToExclude
are essentially ignored.
Only if testName
is None
will tagsToInclude
and tagsToExclude
be consulted to
determine which of the tests named in the testNames
Set
should be run. For more information on trait tags, see the main documentation for this trait.
If testName
is None
, this trait's implementation of this method
invokes testNames
on this Suite
to get a Set
of names of tests to potentially execute.
(A testNames
value of None
essentially acts as a wildcard that means all tests in
this Suite
that are selected by tagsToInclude
and tagsToExclude
should be executed.)
For each test in the testName
Set
, in the order
they appear in the iterator obtained by invoking the elements
method on the Set
, this trait's implementation
of this method checks whether the test should be run based on the tagsToInclude
and tagsToExclude
Set
s.
If so, this implementation invokes runTest
, passing in:
testName
- the String
name of the test to run (which will be one of the names in the testNames
Set
)reporter
- the Reporter
passed to this method, or one that wraps and delegates to itstopper
- the Stopper
passed to this method, or one that wraps and delegates to itconfigMap
- the configMap
passed to this method, or one that wraps and delegates to ittestName -
an optional name of one test to run. If None
, all relevant tests should be run. I.e., None
acts like a wildcard that means run all relevant tests in this Suite
.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.filter -
a Filter
with which to filter tests based on their tagsconfigMap -
a Map
of key-value pairs that can be used by the executing Suite
of tests.distributor -
an optional Distributor
, into which to put nested Suite
s to be run by another entity, such as concurrently by a pool of threads. If None
, nested Suite
s will be run sequentially.tracker -
a Tracker
tracking Ordinal
s being fired by the current thread.NullPointerException -
if any of the passed parameters is null
.IllegalArgumentException -
if testName
is defined, but no test with the specified test name exists in this Suite
override
def
testNames : scala.collection.immutable.Set[java.lang.String]
Set
of test names. If this FeatureSpec
contains no tests, this method returns an
empty Set
.
This trait's implementation of this method will return a set that contains the names of all registered tests. The set's
iterator will return those names in the order in which the tests were registered. Each test's name is composed
of the concatenation of the text of each surrounding describer, in order from outside in, and the text of the
example itself, with all components separated by a space. For example, consider this FeatureSpec
:
import org.scalatest.FeatureSpec class StackSpec extends FeatureSpec { feature("A Stack") { scenario("(when not empty) must allow me to pop") {} scenario("(when not full) must allow me to push") {} } }
Invoking testNames
on this Spec
will yield a set that contains the following
two test name strings:
"A Stack (when not empty) must allow me to pop" "A Stack (when not full) must allow me to push"
override
def
run(testName : scala.Option[java.lang.String], reporter : Reporter, stopper : Stopper, filter : Filter, configMap : scala.collection.immutable.Map[java.lang.String, Any], distributor : scala.Option[Distributor], tracker : Tracker) : Unit
If testName
is None
, this trait's implementation of this method
calls these two methods on this object in this order:
runNestedSuites(report, stopper, tagsToInclude, tagsToExclude, configMap, distributor)
runTests(testName, report, stopper, tagsToInclude, tagsToExclude, configMap)
If testName
is defined, then this trait's implementation of this method
calls runTests
, but does not call runNestedSuites
. This behavior
is part of the contract of this method. Subclasses that override run
must take
care not to call runNestedSuites
if testName
is defined. (The
OneInstancePerTest
trait depends on this behavior, for example.)
Subclasses and subtraits that override this run
method can implement them without
invoking either the runTests
or runNestedSuites
methods, which
are invoked by this trait's implementation of this method. It is recommended, but not required,
that subclasses and subtraits that override run
in a way that does not
invoke runNestedSuites
also override runNestedSuites
and make it
final. Similarly it is recommended, but not required,
that subclasses and subtraits that override run
in a way that does not
invoke runTests
also override runTests
(and runTest
,
which this trait's implementation of runTests
calls) and make it
final. The implementation of these final methods can either invoke the superclass implementation
of the method, or throw an UnsupportedOperationException
if appropriate. The
reason for this recommendation is that ScalaTest includes several traits that override
these methods to allow behavior to be mixed into a Suite
. For example, trait
BeforeAndAfterEach
overrides runTests
s. In a Suite
subclass that no longer invokes runTests
from run
, the
BeforeAndAfterEach
trait is not applicable. Mixing it in would have no effect.
By making runTests
final in such a Suite
subtrait, you make
the attempt to mix BeforeAndAfterEach
into a subclass of your subtrait
a compiler error. (It would fail to compile with a complaint that BeforeAndAfterEach
is trying to override runTests
, which is a final method in your trait.)
testName -
an optional name of one test to run. If None
, all relevant tests should be run. I.e., None
acts like a wildcard that means run all relevant tests in this Suite
.reporter -
the Reporter
to which results will be reportedstopper -
the Stopper
that will be consulted to determine whether to stop execution early.filter -
a Filter
with which to filter tests based on their tagsconfigMap -
a Map
of key-value pairs that can be used by the executing Suite
of tests.distributor -
an optional Distributor
, into which to put nested Suite
s to be run by another entity, such as concurrently by a pool of threads. If None
, nested Suite
s will be run sequentially.tracker -
a Tracker
tracking Ordinal
s being fired by the current thread.NullPointerException -
if any passed parameter is null
.IllegalArgumentException -
if testName
is defined, but no test with the specified test name exists in this Suite
This method enables the following syntax for shared scenarios in a FeatureSpec
:
scenariosFor(nonEmptyStack(lastValuePushed))
This method just provides syntax sugar intended to make the intent of the code clearer.
Because the parameter passed to it is
type Unit
, the expression will be evaluated before being passed, which
is sufficient to register the shared scenarios. For examples of shared scenarios, see the
Shared scenarios section in the main documentation for this trait.
ScalaTest 1.0
|
|