Class used via an implicit conversion to enable any two objects to be compared with
===
in assertions in tests
Assert that an Option[String]
is None
Assert that an Option[String]
is None
.
If the condition is None
, this method returns normally.
Else, it throws TestFailedException
with the String
value of the Some
included in the TestFailedException
's
detail message.
This form of assert
is usually called in conjunction with an
implicit conversion to Equalizer
, using a ===
comparison, as in:
assert(a === b)
For more information on how this mechanism works, see the documentation for
Equalizer
.
the Option[String]
to assert
Assert that an Option[String]
is None
Assert that an Option[String]
is None
.
If the condition is None
, this method returns normally.
Else, it throws TestFailedException
with the String
value of the Some
, as well as the
String
obtained by invoking toString
on the
specified message
,
included in the TestFailedException
's detail message.
This form of assert
is usually called in conjunction with an
implicit conversion to Equalizer
, using a ===
comparison, as in:
assert(a === b, "extra info reported if assertion fails")
For more information on how this mechanism works, see the documentation for
Equalizer
.
the Option[String]
to assert
An objects whose toString
method returns a message to include in a failure report.
Assert that a boolean condition, described in String
message
, is true
Assert that a boolean condition, described in String
message
, is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
with the
String
obtained by invoking toString
on the
specified message
as the exception's detail message.
the boolean condition to assert
An objects whose toString
method returns a message to include in a failure report.
Assert that a boolean condition is true
Assert that a boolean condition is true.
If the condition is true
, this method returns normally.
Else, it throws TestFailedException
.
the boolean condition to assert
Implicit conversion from Any
to Equalizer
, used to enable
assertions with ===
comparisons
Implicit conversion from Any
to Equalizer
, used to enable
assertions with ===
comparisons.
For more information on this mechanism, see the documentation for Equalizer.
Because trait Suite
mixes in Assertions
, this implicit conversion will always be
available by default in ScalaTest Suite
s. This is the only implicit conversion that is in scope by default in every
ScalaTest Suite
. Other implicit conversions offered by ScalaTest, such as those that support the matchers DSL
or invokePrivate
, must be explicitly invited into your test code, either by mixing in a trait or importing the
members of its companion object. The reason ScalaTest requires you to invite in implicit conversions (with the exception of the
implicit conversion for ===
operator) is because if one of ScalaTest's implicit conversions clashes with an
implicit conversion used in the code you are trying to test, your program won't compile. Thus there is a chance that if you
are ever trying to use a library or test some code that also offers an implicit conversion involving a ===
operator,
you could run into the problem of a compiler error due to an ambiguous implicit conversion. If that happens, you can turn off
the implicit conversion offered by this convertToEqualizer
method simply by overriding the method in your
Suite
subclass, but not marking it as implicit:
// In your Suite subclass override def convertToEqualizer(left: Any) = new Equalizer(left)
the object whose type to convert to Equalizer
.
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence.
The default implementations of this method is an equivalence relation:
x
of type Any
,
x.equals(x)
should return true
.x
and y
of type
Any
, x.equals(y)
should return true
if and only
if y.equals(x)
returns true
.x
, y
, and z
of type AnyRef
if x.equals(y)
returns true
and
y.equals(z)
returns
true
, then x.equals(z)
should return true
.
If you override this method, you should verify that
your implementation remains an equivalence relation.
Additionally, when overriding this method it is often necessary to
override hashCode
to ensure that objects that are
"equal" (o1.equals(o2)
returns true
)
hash to the same Int
(o1.hashCode.equals(o2.hashCode)
).
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
Expect that the value passed as expected
equals the value passed as actual
Expect that the value passed as expected
equals the value passed as actual
.
If the actual
value equals the expected
value
(as determined by ==
), expect
returns
normally. Else, expect
throws an
TestFailedException
whose detail message includes the expected and actual values.
the expected value
the actual value, which should equal the passed expected
value
Expect that the value passed as expected
equals the value passed as actual
Expect that the value passed as expected
equals the value passed as actual
.
If the actual
equals the expected
(as determined by ==
), expect
returns
normally. Else, if actual
is not equal to expected
, expect
throws an
TestFailedException
whose detail message includes the expected and actual values, as well as the String
obtained by invoking toString
on the passed message
.
the expected value
An object whose toString
method returns a message to include in a failure report.
the actual value, which should equal the passed expected
value
The total number of tests that are expected to run when this Suite
's run
method is invoked
The total number of tests that are expected to run when this Suite
's run
method is invoked.
This trait's implementation of this method returns the sum of:
testNames
List
, minus the number of tests marked as ignored
expectedTestCount
on every nested Suite
contained in
nestedSuites
a Filter
with which to filter tests to count based on their tags
Throws TestFailedException
, with the passed
Throwable
cause, to indicate a test failed
Throws TestFailedException
, with the passed
Throwable
cause, to indicate a test failed.
The getMessage
method of the thrown TestFailedException
will return cause.toString()
.
a Throwable
that indicates the cause of the failure.
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message and Throwable
cause, to indicate a test failed.
A message describing the failure.
A Throwable
that indicates the cause of the failure.
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message, to indicate a test failed
Throws TestFailedException
, with the passed
String
message
as the exception's detail
message, to indicate a test failed.
A message describing the failure.
Throws TestFailedException
to indicate a test failed
Throws TestFailedException
to indicate a test failed.
Returns a hash code value for the object
Returns a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash
codes (o1.hashCode.equals(o2.hashCode)
) yet not be
equal (o1.equals(o2)
returns false
). A
degenerate implementation could always return 0
.
However, it is required that if two objects are equal
(o1.equals(o2)
returns true
) that they
have identical hash codes
(o1.hashCode.equals(o2.hashCode)
). Therefore, when
overriding this method, be sure to verify that the behavior is
consistent with the equals
method.
Intercept and return an exception that's expected to be thrown by the passed function value
Intercept and return an exception that's expected to
be thrown by the passed function value. The thrown exception must be an instance of the
type specified by the type parameter of this method. This method invokes the passed
function. If the function throws an exception that's an instance of the specified type,
this method returns that exception. Else, whether the passed function returns normally
or completes abruptly with a different exception, this method throws TestFailedException
.
Note that the type specified as this method's type parameter may represent any subtype of
AnyRef
, not just Throwable
or one of its subclasses. In
Scala, exceptions can be caught based on traits they implement, so it may at times make sense
to specify a trait that the intercepted exception's class must mix in. If a class instance is
passed for a type that could not possibly be used to catch an exception (such as String
,
for example), this method will complete abruptly with a TestFailedException
.
the function value that should throw the expected exception
an implicit Manifest
representing the type of the specified
type parameter.
the intercepted exception, if it is of the expected type
A List
of this Suite
object's nested Suite
s
A List
of this Suite
object's nested Suite
s. If this Suite
contains no nested Suite
s,
this method returns an empty List
. This trait's implementation of this method returns an empty List
.
Throws TestPendingException
to indicate a test is pending
Throws TestPendingException
to indicate a test is pending.
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 it is intended to test, has not yet been implemented.
Note: This method always completes abruptly with a TestPendingException
. Thus it always has a side
effect. Methods with side effects are usually invoked with parentheses, as in pending()
. This
method is defined as a parameterless method, in flagrant contradiction to recommended Scala style, because it
forms a kind of DSL for pending tests. It enables tests in suites such as FunSuite
or Spec
to be denoted by placing "(pending)
" after the test name, as in:
test("that style rules are not laws") (pending)
Readers of the code see "pending" in parentheses, which looks like a little note attached to the test name to indicate
it is pending. Whereas "(pending())
looks more like a method call, "(pending)
" lets readers
stay at a higher level, forgetting how it is implemented and just focusing on the intent of the programmer who wrote the code.
Execute the passed block of code, and if it completes abruptly, throw TestPendingException
, else
throw TestFailedException
Execute the passed block of code, and if it completes abruptly, throw TestPendingException
, else
throw TestFailedException
.
This method can be used to temporarily change a failing test into a pending test in such a way that it will
automatically turn back into a failing test once the problem originally causing the test to fail has been fixed.
At that point, you need only remove the pendingUntilFixed
call. In other words, a
pendingUntilFixed
surrounding a block of code that isn't broken is treated as a test failure.
The motivation for this behavior is to encourage people to remove pendingUntilFixed
calls when
there are no longer needed.
This method facilitates a style of testing in which tests are written before the code they test. Sometimes you may
encounter a test failure that requires more functionality than you want to tackle without writing more tests. In this
case you can mark the bit of test code causing the failure with pendingUntilFixed
. You can then write more
tests and functionality that eventually will get your production code to a point where the original test won't fail anymore.
At this point the code block marked with pendingUntilFixed
will no longer throw an exception (because the
problem has been fixed). This will in turn cause pendingUntilFixed
to throw TestFailedException
with a detail message explaining you need to go back and remove the pendingUntilFixed
call as the problem orginally
causing your test code to fail has been fixed.
a block of code, which if it completes abruptly, should trigger a TestPendingException
Runs this suite of tests
Runs this suite of tests.
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.)
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
.
the Reporter
to which results will be reported
the Stopper
that will be consulted to determine whether to stop execution early.
a Filter
with which to filter tests based on their tags
a Map
of key-value pairs that can be used by the executing Suite
of tests.
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.
a Tracker
tracking Ordinal
s being fired by the current thread.
A user-friendly suite name for this Suite
A user-friendly suite name for this Suite
.
This trait's
implementation of this method returns the simple name of this object's class. This
trait's implementation of runNestedSuites
calls this method to obtain a
name for Report
s to pass to the suiteStarting
, suiteCompleted
,
and suiteAborted
methods of the Reporter
.
A Map
whose keys are String
tag names with which tests in this Suite
are marked, and
whose values are the Set
of test names marked with each tag
A Map
whose keys are String
tag names with which tests in this Suite
are marked, and
whose values are the Set
of test names marked with each tag. If this Suite
contains no tags, this
method returns an empty Map
.
This trait's implementation of this method uses Java reflection to discover any Java annotations attached to its test methods. The
fully qualified name of each unique annotation that extends TagAnnotation
is considered a tag. This trait's
implementation of this method, therefore, places one key/value pair into to the
Map
for each unique tag annotation name discovered through reflection. The mapped value for each tag name key will contain
the test method name, as provided via the testNames
method.
Subclasses may override this method to define and/or discover tags in a custom manner, but overriding method implementations
should never return an empty Set
as a value. If a tag has no tests, its name should not appear as a key in the
returned Map
.
Note, the TagAnnotation
annotation was introduced in ScalaTest 1.0, when "groups" were renamed
to "tags." In 1.0 and 1.1, the TagAnnotation
will continue to not be required by an annotation on a Suite
method. Any annotation on a Suite
method will be considered a tag until 1.2, to give users time to add
TagAnnotation
s on any tag annotations they made prior to the 1.0 release. From 1.2 onward, only annotations
themselves annotated by TagAnnotation
will be considered tag annotations.
An Set
of test names
An Set
of test names. If this Suite
contains no tests, this method returns an empty Set
.
This trait's implementation of this method uses Java reflection to discover all public methods whose name starts with "test"
,
which take either nothing or a single Informer
as parameters. For each discovered test method, it assigns a test name
comprised of just the method name if the method takes no parameters, or the method name plus (Informer)
if the
method takes a Informer
. Here are a few method signatures and the names that this trait's implementation assigns them:
def testCat() {} // test name: "testCat" def testCat(Informer) {} // test name: "testCat(Informer)" def testDog() {} // test name: "testDog" def testDog(Informer) {} // test name: "testDog(Informer)" def test() {} // test name: "test" def test(Informer) {} // test name: "test(Informer)"
This trait's implementation of this method returns an immutable Set
of all such names, excluding the name
testNames
. The iterator obtained by invoking elements
on this
returned Set
will produce the test names in their natural order, as determined by String
's
compareTo
method.
This trait's implementation of runTests
invokes this method
and calls runTest
for each test name in the order they appear in the returned Set
's iterator.
Although this trait's implementation of this method returns a Set
whose iterator produces String
test names in a well-defined order, the contract of this method does not required a defined order. Subclasses are free to
override this method and return test names in an undefined order, or in a defined order that's different from String
's
natural order.
Subclasses may override this method to produce test names in a custom manner. One potential reason to override testNames
is
to run tests in a different order, for example, to ensure that tests that depend on other tests are run after those other tests.
Another potential reason to override is allow tests to be defined in a different manner, such as methods annotated @Test
annotations
(as is done in JUnitSuite
and TestNGSuite
) or test functions registered during construction (as is
done in FunSuite
and Spec
).
Returns a string representation of the object
Returns a string representation of the object.
The default representation is platform dependent.
A suite of tests. A
Suite
instance encapsulates a conceptual suite (i.e., a collection) of tests.This trait provides an interface that allows suites of tests to be run. Its implementation enables a default way of writing and executing tests. Subtraits and subclasses can override
Suite
's methods to enable other ways of writing and executing tests. This trait's default approach allows tests to be defined as methods whose name starts with "test
." This approach is easy to understand, and a good way for Scala beginners to start writing tests. More advanced Scala programmers may prefer to mix together otherSuite
subtraits defined in ScalaTest, or create their own, to write tests in the way they feel makes them most productive. Here's a quick overview of some of the options to help you get started:For JUnit 3 users
If you are using JUnit 3 (version 3.8 or earlier releases) and you want to write JUnit 3 tests in Scala, look at
AssertionsForJUnit
,ShouldMatchersForJUnit
, andJUnit3Suite
.For JUnit 4 users
If you are using JUnit 4 and you want to write JUnit 4 tests in Scala, look at
JUnitSuite
, andJUnitRunner
. WithJUnitRunner
, you can use any of the traits described here and still run your tests with JUnit 4.For TestNG users
If you are using TestNG and you want to write TestNG tests in Scala, look at
TestNGSuite
.For high-level testing
If you want to write tests at a higher level than unit tests, such as integration tests, acceptance tests, or functional tests, check out
FeatureSpec
.For unit testing
If you prefer a behavior-driven development (BDD) style, in which tests are combined with text that specifies the behavior being tested, look at
Spec
,FlatSpec
, andWordSpec
. Otherwise, if you just want to write tests and don't want to combine testing with specifying, look atFunSuite
or read on to learn how to write tests using this base trait,Suite
.To use this trait's approach to writing tests, simply create classes that extend
Suite
and define test methods. Test methods have names of the formtestX
, whereX
is some unique, hopefully meaningful, string. A test method must be public and can have any result type, but the most common result type isUnit
. Here's an example:You can run a
Suite
by invoking on it one of four overloadedexecute
methods. These methods, which print test results to the standard output, are intended to serve as a convenient way to run tests from within the Scala interpreter. For example, to runMySuite
from within the Scala interpreter, you could write:And you would see:
Or, to run just the
testAddition
method, you could write:And you would see:
Two other
execute
methods that are intended to be run from the interpreter accept a "config" map of key-value pairs (see Config map, below). Each of theseexecute
methods invokes arun
method takes seven parameters. Thisrun
method, which actually executes the suite, will usually be invoked by a test runner, such asorg.scalatest.tools.Runner
or an IDE. See the documentation forRunner
for more detail.Assertions and ===
Inside test methods in a
Suite
, you can write assertions by invokingassert
and passing in aBoolean
expression, such as:If the passed expression is
true
,assert
will return normally. Iffalse
,assert
will complete abruptly with aTestFailedException
. This exception is usually not caught by the test method, which means the test method itself will complete abruptly by throwing theTestFailedException
. Any test method that completes abruptly with aTestFailedException
or anyException
is considered a failed test. A test method that returns normally is considered a successful test.If you pass a
Boolean
expression toassert
, a failed assertion will be reported, but without reporting the left and right values. You can alternatively encode these values in aString
passed as a second argument toassert
, as in:Using this form of
assert
, the failure report will include the left and right values, thereby helping you debug the problem. However, ScalaTest provides the===
operator to make this easier. (The===
operator is defined in traitAssertions
which traitSuite
extends.) You use it like this:Because you use
===
here instead of==
, the failure report will include the left and right values. For example, the detail message in the thrownTestFailedException
from theassert
shown previously will include, "2 did not equal 1". From this message you will know that the operand on the left had the value 2, and the operand on the right had the value 1.If you're familiar with JUnit, you would use
===
in a ScalaTestSuite
where you'd useassertEquals
in a JUnitTestCase
. The===
operator is made possible by an implicit conversion fromAny
toEqualizer
. If you're curious to understand the mechanics, see the documentation forEqualizer
and theconvertToEqualizer
method.Expected results
Although
===
provides a natural, readable extension to Scala'sassert
mechanism, as the operands become lengthy, the code becomes less readable. In addition, the===
comparison doesn't distinguish between actual and expected values. The operands are just calledleft
andright
, because if one were namedexpected
and the otheractual
, it would be difficult for people to remember which was which. To help with these limitations of assertions,Suite
includes a method calledexpect
that can be used as an alternative toassert
with===
. To useexpect
, you place the expected value in parentheses afterexpect
, followed by curly braces containing code that should result in the expected value. For example:In this case, the expected value is
2
, and the code being tested isa - b
. This expectation will fail, and the detail message in theTestFailedException
will read, "Expected 2, but got 3."Intercepted exceptions
Sometimes you need to test whether a method throws an expected exception under certain circumstances, such as when invalid arguments are passed to the method. You can do this in the JUnit style, like this:
If
charAt
throwsIndexOutOfBoundsException
as expected, control will transfer to the catch case, which does nothing. If, however,charAt
fails to throw an exception, the next statement,fail()
, will be executed. Thefail
method always completes abruptly with aTestFailedException
, thereby signaling a failed test.To make this common use case easier to express and read, ScalaTest provides an
intercept
method. You use it like this:This code behaves much like the previous example. If
charAt
throws an instance ofIndexOutOfBoundsException
,intercept
will return that exception. But ifcharAt
completes normally, or throws a different exception,intercept
will complete abruptly with aTestFailedException
. Theintercept
method returns the caught exception so that you can inspect it further if you wish, for example, to ensure that data contained inside the exception has the expected values. Here's an example:Using other assertions
ScalaTest also supports another style of assertions via its matchers DSL. By mixing in trait
ShouldMatchers
, you can write suites that look like:If you prefer the word "
must
" to the word "should
," you can alternatively mix in traitMustMatchers
.If you are comfortable with assertion mechanisms from other test frameworks, chances are you can use them with ScalaTest. Any assertion mechanism that indicates a failure with an exception can be used as is with ScalaTest. For example, to use the
assertEquals
methods provided by JUnit or TestNG, simply import them and use them. (You will of course need to include the relevant JAR file for the framework whose assertions you want to use on either the classpath or runpath when you run your tests.) Here's an example in which JUnit's assertions are imported, then used within a ScalaTest suite:Nested suites
A
Suite
can refer to a collection of otherSuite
s, which are called nestedSuite
s. Those nestedSuite
s can in turn have their own nestedSuite
s, and so on. Large test suites can be organized, therefore, as a tree of nestedSuite
s. This trait'srun
method, in addition to invoking its test methods, invokesrun
on each of its nestedSuite
s.A
List
of aSuite
's nestedSuite
s can be obtained by invoking itsnestedSuites
method. If you wish to create aSuite
that serves as a container for nestedSuite
s, whether or not it has test methods of its own, simply overridenestedSuites
to return aList
of the nestedSuite
s. Because this is a common use case, ScalaTest provides a convenienceSuperSuite
class, which takes aList
of nestedSuite
s as a constructor parameter. Here's an example:If you now run
AlphabetSuite
, for example from the interpreter:You will see reports printed to the standard output that indicate nested suites—
ASuite
,BSuite
, andCSuite
—were run.Note that
Runner
can discoverSuite
s automatically, so you need not necessarily specifySuperSuite
s explicitly. See the documentation forRunner
for more information.Shared fixtures
A test fixture is objects or other artifacts (such as files, sockets, database connections, etc.) used by tests to do their work. If a fixture is used by only one test method, then the definitions of the fixture objects can be local to the method, such as the objects assigned to
sum
anddiff
in the previousMySuite
examples. If multiple methods need to share an immutable fixture, one approach is to assign them to instance variables. Here's a (very contrived) example, in which the object assigned toshared
is used by multiple test methods:In some cases, however, shared mutable fixture objects may be changed by test methods such that they need to be recreated or reinitialized before each test. Shared resources such as files or database connections may also need to be created and initialized before, and cleaned up after, each test. JUnit 3 offers methods
setUp
andtearDown
for this purpose. In ScalaTest, you can use theBeforeAndAfterEach
trait, which will be described later, to implement an approach similar to JUnit'ssetUp
andtearDown
, however, this approach usually involves reassigningvar
s between tests. Before going that route, you may wish to consider some approaches that avoidvar
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 method that needs the fixture, storing the fixture object or objects in local variables. Here's an example:If different tests in the same
Suite
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 method requires the same set of mutable fixture objects, one other approach you can take is make them simplyval
s and mix in traitOneInstancePerTest
. If you mix inOneInstancePerTest
, each test will be run in its own instance of theSuite
, 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 theBeforeAndAfterEach
trait.BeforeAndAfterEach
'sbeforeEach
method will be run before, and itsafterEach
method after, each test (like JUnit'ssetUp
andtearDown
methods, respectively). For example, you could create a temporary file before each test, and delete it afterwords, like this:In this example, the instance variable
reader
is avar
, so it can be reinitialized between tests by thebeforeEach
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: overridingwithFixture(NoArgTest)
. To execute each test,Suite
's implementation of therunTest
method wraps an invocation of the appropriate test method in a no-arg function.runTest
passes that test function to thewithFixture(NoArgTest)
method, which is responsible for actually running the test by invoking the function.Suite
's implementation ofwithFixture(NoArgTest)
simply invokes the function, like this: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 inBeforeAndAfterEach
, like this:If you prefer to keep your test classes immutable, one final variation is to use the
FixtureSuite
trait from theorg.scalatest.fixture
package. Tests in anorg.scalatest.fixture.FixtureSuite
can have a fixture object passed in as a parameter. You must indicate the type of the fixture object by defining theFixture
type member and define awithFixture
method that takes a one-arg test function. (AFixtureSuite
has two overloadedwithFixture
methods, therefore, one that takes aOneArgTest
and the other, inherited fromSuite
, that takes aNoArgTest
.) Inside thewithFixture(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, aFixtureSuite
will pass a function that invokes the code of a test towithFixture(OneArgTest)
. YourwithFixture(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 thewithFixture(OneArgTest)
method of aFixtureSuite
, like this:It is worth noting that the only difference in the test code between the mutable
BeforeAndAfterEach
approach shown previously and the immutableFixtureSuite
approach shown here is that two of theFixtureSuite
's test methods take aFileReader
as a parameter. Otherwise the test code is identical. One benefit of the explicit parameter is that, as demonstrated by thetestWithoutAFixture
method, aFixtureSuite
test method need not take the fixture. (Tests that don't take a fixture as a parameter are passed to thewithFixture
that takes aNoArgTest
, shown previously.) So you can have some tests that take a fixture, and others that don't. In this case, theFixtureSuite
provides documentation indicating which test methods use the fixture and which don't, whereas theBeforeAndAfterEach
approach does not.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 thebeforeAll
andafterAll
methods ofBeforeAndAfterAll
. See the documentation forBeforeAndAfterAll
for an example.The config map
In some cases you may need to pass information to a suite of tests. For example, perhaps a suite of tests needs to grab information from a file, and you want to be able to specify a different filename during different runs. You can accomplish this in ScalaTest by passing the filename in the config map of key-value pairs, which is passed to
run
as aMap[String, Any]
. The values in the config map are called "config objects," because they can be used to configure suites, reporters, and tests.You can specify a string config object is via the ScalaTest
Runner
, either via the command line or ScalaTest's ant task. (See the documentation for Runner for information on how to specify config objects on the command line.) The config map is passed torun
,runNestedSuites
,runTests
, andrunTest
, so one way to access it in your suite is to override one of those methods. If you need to use the config map inside your tests, you can use one of the traits in theorg.scalatest.fixture
package. (See the documentation forFixtureSuite
for instructions on how to access the config map in tests.)Tagging tests
A
Suite
's tests may be classified into groups by tagging them with string names. When executing aSuite
, groups of tests can optionally be included and/or excluded. In this trait's implementation, tags are indicated by annotations attached to the test method. To create a new tag type to use inSuite
s, simply define a new Java annotation that itself is annotated with theorg.scalatest.TagAnnotation
annotation. (Currently, for annotations to be visible in Scala programs via Java reflection, the annotations themselves must be written in Java.) For example, to create a tag namedSlowAsMolasses
, to use to mark slow tests, you would write in Java: