Spec
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package scalatest
Helper class used by code generated by the assert macro.
Helper class used by code generated by the assert macro.
A test function taking no arguments and returning an Outcome.
A test function taking no arguments and returning an Outcome.
For more detail and examples, see the relevant section in the
documentation for trait fixture.FlatSpec.
Returns an Alerter that during test execution will forward strings (and other objects) passed to its
apply method to the current reporter.
Returns an Alerter 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
Spec 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
print to the standard output. This method can be called safely by any thread.
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 a helpful error message
appended with the String obtained by invoking toString on the
specified clue as the exception's detail message.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
At this time, any other form of expression will just get a TestFailedException with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean
to be the default in tests. This makes === consistent between tests and production
code.
the boolean condition to assert
An objects whose toString method returns a message to include in a failure report.
NullArgumentException if message is null.
TestFailedException if the condition is false.
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.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
At this time, any other form of expression will get a TestFailedException with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean
to be the default in tests. This makes === consistent between tests and production
code.
the boolean condition to assert
TestFailedException if the condition is false.
Asserts that a given string snippet of code passes both the Scala parser and type checker.
Asserts that a given string snippet of code passes both the Scala parser and type checker.
You can use this to make sure a snippet of code compiles:
assertCompiles("val a: Int = 1")
Although assertCompiles is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string compiles, errors (i.e.,
snippets of code that do not compile) are reported as test failures at runtime.
the snippet of code that should compile
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Often when creating libraries you may wish to ensure that certain arrangements of code that
represent potential “user errors” do not compile, so that your library is more error resistant.
ScalaTest's Assertions trait includes the following syntax for that purpose:
assertDoesNotCompile("val a: String = \"a string")
Although assertDoesNotCompile is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string doesn't compile, errors (i.e.,
snippets of code that do compile) are reported as test failures at runtime.
Note that the difference between assertTypeError and assertDoesNotCompile is
that assertDoesNotCompile will succeed if the given code does not compile for any reason,
whereas assertTypeError will only succeed if the given code does not compile because of
a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile
will return normally but assertTypeError will throw a TestFailedException.
the snippet of code that should not type check
Assert that the value passed as expected equals the value passed as actual.
Assert that the value passed as expected equals the value passed as actual.
If the actual value equals the expected value
(as determined by ==), assertResult returns
normally. Else, assertResult throws a
TestFailedException whose detail message includes the expected and actual values.
the expected value
the actual value, which should equal the passed expected value
TestFailedException if the passed actual value does not equal the passed expected value.
Assert that the value passed as expected equals the value passed as actual.
Assert that the value passed as expected equals the value passed as actual.
If the actual equals the expected
(as determined by ==), assertResult returns
normally. Else, if actual is not equal to expected, assertResult throws a
TestFailedException whose detail message includes the expected and actual values, as well as the String
obtained by invoking toString on the passed clue.
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
TestFailedException if the passed actual value does not equal the passed expected value.
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Often when creating libraries you may wish to ensure that certain arrangements of code that
represent potential “user errors” do not compile, so that your library is more error resistant.
ScalaTest's Assertions trait includes the following syntax for that purpose:
assertTypeError("val a: String = 1")
Although assertTypeError is implemented with a macro that determines at compile time whether
the snippet of code represented by the passed string type checks, errors (i.e.,
snippets of code that do type check) are reported as test failures at runtime.
Note that the difference between assertTypeError and assertDoesNotCompile is
that assertDoesNotCompile will succeed if the given code does not compile for any reason,
whereas assertTypeError will only succeed if the given code does not compile because of
a type error. If the given code does not compile because of a syntax error, for example, assertDoesNotCompile
will return normally but assertTypeError will throw a TestFailedException.
the snippet of code that should not type check
Helper instance used by code generated by macro assertion.
Helper instance used by code generated by macro assertion.
Assume that a boolean condition, described in String
message, is true.
Assume that a boolean condition, described in String
message, is true.
If the condition is true, this method returns normally.
Else, it throws TestCanceledException with a helpful error message
appended with String obtained by invoking toString on the
specified clue as the exception's detail message.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
At this time, any other form of expression will just get a TestCanceledException with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean
to be the default in tests. This makes === consistent between tests and production
code.
the boolean condition to assume
An objects whose toString method returns a message to include in a failure report.
NullArgumentException if message is null.
TestCanceledException if the condition is false.
Assume that a boolean condition is true.
Assume that a boolean condition is true.
If the condition is true, this method returns normally.
Else, it throws TestCanceledException.
This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
At this time, any other form of expression will just get a TestCanceledException with message saying the given
expression was false. In the future, we will enhance this macro to give helpful error messages in more situations.
In ScalaTest 2.0, however, this behavior was sufficient to allow the === that returns Boolean
to be the default in tests. This makes === consistent between tests and production
code.
the boolean condition to assume
TestCanceledException if the condition is false.
Throws TestCanceledException, with the passed
Throwable cause, to indicate a test failed.
Throws TestCanceledException, with the passed
Throwable cause, to indicate a test failed.
The getMessage method of the thrown TestCanceledException
will return cause.toString.
a Throwable that indicates the cause of the cancellation.
NullArgumentException if cause is null
Throws TestCanceledException, with the passed
String message as the exception's detail
message and Throwable cause, to indicate a test failed.
Throws TestCanceledException, 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.
NullArgumentException if message or cause is null
Throws TestCanceledException, with the passed
String message as the exception's detail
message, to indicate a test was canceled.
Throws TestCanceledException, with the passed
String message as the exception's detail
message, to indicate a test was canceled.
A message describing the cancellation.
NullArgumentException if message is null
Throws TestCanceledException to indicate a test was canceled.
Throws TestCanceledException to indicate a test was canceled.
Executes this Suite, printing results to the standard output.
Executes this Suite, printing results to the standard output.
This method, which simply invokes the other overloaded form of execute with default parameter values,
is intended for use only as a mini-DSL for the Scala interpreter. It allows you to execute a Suite in the
interpreter with a minimum of finger typing:
scala> new SetSpec execute An empty Set - should have size 0 - should produce NoSuchElementException when head is invoked !!! IGNORED !!!
If you do ever want to invoke execute outside the Scala interpreter, it is best style to invoke it with
empty parens to indicate it has a side effect, like this:
// Use empty parens form in regular code (outside the Scala interpreter) (new ExampleSuite).execute()
Executes one or more tests in this Suite, printing results to the standard output.
Executes one or more tests in this Suite, printing results to the standard output.
This method invokes run on itself, passing in values that can be configured via the parameters to this
method, all of which have default values. This behavior is convenient when working with ScalaTest in the Scala interpreter.
Here's a summary of this method's parameters and how you can use them:
The testName parameter
If you leave testName at its default value (of null), this method will pass None to
the testName parameter of run, and as a result all the tests in this suite will be executed. If you
specify a testName, this method will pass Some(testName) to run, and only that test
will be run. Thus to run all tests in a suite from the Scala interpreter, you can write:
scala> new ExampleSuite execute
(The above syntax actually invokes the overloaded parameterless form of execute, which calls this form with its default parameter values.)
To run just the test named "my favorite test" in a suite from the Scala interpreter, you would write:
scala> new ExampleSuite execute ("my favorite test")
Or:
scala> new ExampleSuite execute (testName = "my favorite test")
The configMap parameter
If you provide a value for the configMap parameter, this method will pass it to run. If not, the default value
of an empty Map will be passed. For more information on how to use a config map to configure your test suites, see
the config map section in the main documentation for this trait. Here's an example in which you configure
a run with the name of an input file:
scala> new ExampleSuite execute (configMap = Map("inputFileName" -> "in.txt")
The color parameter
If you leave the color parameter unspecified, this method will configure the reporter it passes to run to print
to the standard output in color (via ansi escape characters). If you don't want color output, specify false for color, like this:
scala> new ExampleSuite execute (color = false)
The durations parameter
If you leave the durations parameter unspecified, this method will configure the reporter it passes to run to
not print durations for tests and suites to the standard output. If you want durations printed, specify true for durations,
like this:
scala> new ExampleSuite execute (durations = true)
The shortstacks and fullstacks parameters
If you leave both the shortstacks and fullstacks parameters unspecified, this method will configure the reporter
it passes to run to not print stack traces for failed tests if it has a stack depth that identifies the offending
line of test code. If you prefer a short stack trace (10 to 15 stack frames) to be printed with any test failure, specify true for
shortstacks:
scala> new ExampleSuite execute (shortstacks = true)
For full stack traces, set fullstacks to true:
scala> new ExampleSuite execute (fullstacks = true)
If you specify true for both shortstacks and fullstacks, you'll get full stack traces.
The stats parameter
If you leave the stats parameter unspecified, this method will not fire RunStarting and either RunCompleted
or RunAborted events to the reporter it passes to run.
If you specify true for stats, this method will fire the run events to the reporter, and the reporter will print the
expected test count before the run, and various statistics after, including the number of suites completed and number of tests that
succeeded, failed, were ignored or marked pending. Here's how you get the stats:
scala> new ExampleSuite execute (stats = true)
To summarize, this method will pass to run:
testName - None if this method's testName parameter is left at its default value of null, else Some(testName).reporter - a reporter that prints to the standard outputstopper - a Stopper whose apply method always returns falsefilter - a Filter constructed with None for tagsToInclude and Set()
for tagsToExcludeconfigMap - the configMap passed to this methoddistributor - Nonetracker - a new TrackerNote: In ScalaTest, the terms "execute" and "run" basically mean the same thing and
can be used interchangably. The reason this method isn't named run is that it takes advantage of
default arguments, and you can't mix overloaded methods and default arguments in Scala. (If named run,
this method would have the same name but different arguments than the main run method that
takes seven arguments. Thus it would overload and couldn't be used with default argument values.)
Design note: This method has two "features" that may seem unidiomatic. First, the default value of testName is null.
Normally in Scala the type of testName would be Option[String] and the default value would
be None, as it is in this trait's run method. The null value is used here for two reasons. First, in
ScalaTest 1.5, execute was changed from four overloaded methods to one method with default values, taking advantage of
the default and named parameters feature introduced in Scala 2.8.
To not break existing source code, testName needed to have type String, as it did in two of the overloaded
execute methods prior to 1.5. The other reason is that execute has always been designed to be called primarily
from an interpeter environment, such as the Scala REPL (Read-Evaluate-Print-Loop). In an interpreter environment, minimizing keystrokes is king.
A String type with a null default value lets users type suite.execute("my test name") rather than
suite.execute(Some("my test name")), saving several keystrokes.
The second non-idiomatic feature is that shortstacks and fullstacks are all lower case rather than
camel case. This is done to be consistent with the Shell, which also uses those forms. The reason
lower case is used in the Shell is to save keystrokes in an interpreter environment. Most Unix commands, for
example, are all lower case, making them easier and quicker to type. In the ScalaTest
Shell, methods like shortstacks, fullstacks, and nostats, etc., are
designed to be all lower case so they feel more like shell commands than methods.
the name of one test to run.
a Map of key-value pairs that can be used by the executing Suite of tests.
a boolean that configures whether output is printed in color
a boolean that configures whether test and suite durations are printed to the standard output
a boolean that configures whether short stack traces should be printed for test failures
a boolean that configures whether full stack traces should be printed for test failures
a boolean that configures whether test and suite statistics are printed to the standard output
IllegalArgumentException if testName is defined, but no test with the specified test name
exists in this Suite
NullArgumentException if the passed configMap parameter is null.
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 and
any tests that are exluded by the passed FilterexpectedTestCount on every nested Suite contained in
nestedSuitesa 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.
NullArgumentException if cause is null
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.
NullArgumentException if message or cause is null
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.
NullArgumentException if message is null
Throws TestFailedException to indicate a test failed.
Throws TestFailedException to indicate a test failed.
Returns an Informer that during test execution will forward strings passed to its
apply method to the current reporter.
Returns an Informer that during test execution will forward strings 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 from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
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 ClassTag representing the type of the specified
type parameter.
the intercepted exception, if it is of the expected type
TestFailedException if the passed function does not complete abruptly with an exception
that's an instance of the specified type
passed expected value.
Returns a Documenter that during test execution will forward strings passed to its
apply method to the current reporter.
Returns a Documenter that during test execution will forward strings 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 from inside a scope,
it will forward the information to the current reporter immediately. If invoked from inside a test function,
it will record the information and forward it to the current reporter only after the test completed, as recordedEvents
of the test completed event, such as TestSucceeded. If invoked at any other time, it will print to the standard output.
This method can be called safely by any thread.
An immutable IndexedSeq of this Suite object's nested Suites.
An immutable IndexedSeq of this Suite object's nested Suites. If this Suite contains no nested Suites,
this method returns an empty IndexedSeq. This trait's implementation of this method returns an empty List.
Returns a Notifier that during test execution will forward strings (and other objects) passed to its
apply method to the current reporter.
Returns a Notifier 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
Spec 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
print to the standard output. This method can be called safely by any thread.
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 FunSpec
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
TestPendingException if the passed block of code completes abruptly with an Exception or AssertionError
The fully qualified class name of the rerunner to rerun this suite.
The fully qualified class name of the rerunner to rerun this suite. This implementation will look at this.getClass and see if it is either an accessible Suite, or it has a WrapWith annotation. If so, it returns the fully qualified class name wrapped in a Some, or else it returns None.
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:
runNestedSuitesrunTestsIf 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 runTestss. 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 Args for this run
a Status object that indicates when all tests and nested suites started by this method have completed, and whether or not a failure occurred.
Run zero to many of this Suite's nested Suites.
Run zero to many of this Suite's nested Suites.
If the passed distributor is None, this trait's
implementation of this method invokes run on each
nested Suite in the List obtained by invoking nestedSuites.
If a nested Suite's run
method completes abruptly with an exception, this trait's implementation of this
method reports that the Suite aborted and attempts to run the
next nested Suite.
If the passed distributor is defined, this trait's implementation
puts each nested Suite
into the Distributor contained in the Some, in the order in which the
Suites appear in the List returned by nestedSuites, passing
in a new Tracker obtained by invoking nextTracker on the Tracker
passed to this method.
Implementations of this method are responsible for ensuring SuiteStarting events
are fired to the Reporter before executing any nested Suite, and either SuiteCompleted
or SuiteAborted after executing any nested Suite.
the Args for this run
a Status object that indicates when all nested suites started by this method have completed, and whether or not a failure occurred.
NullArgumentException if any passed parameter is null.
Run a test.
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.)
the name of one test to execute.
the Args for this run
a Status object that indicates when the test started by this method has completed, and whether or not it failed .
Run zero to many of this Spec's tests.
Run zero to many of this Spec's tests.
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 Args for this run
a Status object that indicates when all tests started by this method have completed, and whether or not a failure occurred.
Suite style name.
A string ID for this Suite that is intended to be unique among all suites reported during a run.
A string ID for this Suite that is intended to be unique among all suites reported during a run.
This trait's
implementation of this method returns the fully qualified name of this object's class.
Each suite reported during a run will commonly be an instance of a different Suite class,
and in such cases, this default implementation of this method will suffice. However, in special cases
you may need to override this method to ensure it is unique for each reported suite. For example, if you write
a Suite subclass that reads in a file whose name is passed to its constructor and dynamically
creates a suite of tests based on the information in that file, you will likely need to override this method
in your Suite subclass, perhaps by appending the pathname of the file to the fully qualified class name.
That way if you run a suite of tests based on a directory full of these files, you'll have unique suite IDs for
each reported suite.
The suite ID is intended to be unique, because ScalaTest does not enforce that it is unique. If it is not unique, then you may not be able to uniquely identify a particular test of a particular suite. This ability is used, for example, to dynamically tag tests as having failed in the previous run when rerunning only failed tests.
this Suite object's ID.
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 Reports to pass to the suiteStarting, suiteCompleted,
and suiteAborted methods of the Reporter.
this Suite object's suite name.
A Map whose keys are String names of tagged tests and whose associated values are
the Set of tags for the test.
A Map whose keys are String names of tagged tests and whose associated values are
the Set of tags for the test. If this Spec 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 test for which a tag annotation is discovered through reflection.
In addition, this trait's implementation will also auto-tag tests with class level annotations.
For example, if you annotate @Ignore at the class level, all test methods in the class will be auto-annotated with
org.scalatest.Ignore.
Provides a TestData instance for the passed test name, given the passed config map.
Provides a TestData instance for the passed test name, given the passed config map.
This method is used to obtain a TestData instance to pass to withFixture(NoArgTest)
and withFixture(OneArgTest) and the beforeEach and afterEach methods
of trait BeforeAndAfterEach.
the name of the test for which to return a TestData instance
the config map to include in the returned TestData
a TestData instance for the specified test, which includes the specified config map
An immutable Set of test names.
An immutable Set of test names. If this Spec 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 Spec:
import org.scalatest.Spec
class StackSpec extends Spec {
object `A Stack` {
object `(when not empty)` {
def `must allow me to pop` {}
}
object `(when not full)` {
def `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"
Returns a user friendly string for this suite, composed of the
simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite
contains nested suites, the result of invoking toString on each
of the nested suites, separated by commas and surrounded by parentheses.
Returns a user friendly string for this suite, composed of the
simple name of the class (possibly simplified further by removing dollar signs if added by the Scala interpeter) and, if this suite
contains nested suites, the result of invoking toString on each
of the nested suites, separated by commas and surrounded by parentheses.
a user-friendly string for this suite
Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException
indicating no exception is thrown.
Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new RuntimeException
indicating no exception is thrown.
This method is intended to be used in the Scala interpreter to eliminate large stack traces when trying out ScalaTest assertions and
matcher expressions. It is not intended to be used in regular test code. If you want to ensure that a bit of code throws an expected
exception, use intercept, not trap. Here's an example interpreter session without trap:
scala> import org.scalatest._ import org.scalatest._ scala> import Matchers._ import Matchers._ scala> val x = 12 a: Int = 12 scala> x shouldEqual 13 org.scalatest.exceptions.TestFailedException: 12 did not equal 13 at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:449) at org.scalatest.Assertions$.newAssertionFailedException(Assertions.scala:1203) at org.scalatest.Assertions$AssertionsHelper.macroAssertTrue(Assertions.scala:417) at .<init>(<console>:15) at .<clinit>(<console>) at .<init>(<console>:7) at .<clinit>(<console>) at $print(<console>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:731) at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:980) at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:570) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:601) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565) at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745) at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790) at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702) at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566) at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573) at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135) at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822) at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83) at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96) at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105) at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
That's a pretty tall stack trace. Here's what it looks like when you use trap:
scala> trap { x shouldEqual 13 }
res1: Throwable = org.scalatest.exceptions.TestFailedException: 12 did not equal 13
Much less clutter. Bear in mind, however, that if no exception is thrown by the
passed block of code, the trap method will create a new NormalResult
(a subclass of Throwable made for this purpose only) and return that. If the result was the Unit value, it
will simply say that no exception was thrown:
scala> trap { x shouldEqual 12 }
res2: Throwable = No exception was thrown.
If the passed block of code results in a value other than Unit, the NormalResult's toString will print the value:
scala> trap { "Dude!" }
res3: Throwable = No exception was thrown. Instead, result was: "Dude!"
Although you can access the result value from the NormalResult, its type is Any and therefore not
very convenient to use. It is not intended that trap be used in test code. The sole intended use case for trap is decluttering
Scala interpreter sessions by eliminating stack traces when executing assertion and matcher expressions.
Executes the block of code passed as the second parameter, and, if it
completes abruptly with a ModifiableMessage exception,
prepends the "clue" string passed as the first parameter to the beginning of the detail message
of that thrown exception, then rethrows it.
Executes the block of code passed as the second parameter, and, if it
completes abruptly with a ModifiableMessage exception,
prepends the "clue" string passed as the first parameter to the beginning of the detail message
of that thrown exception, then rethrows it. If clue does not end in a white space
character, one space will be added
between it and the existing detail message (unless the detail message is
not defined).
This method allows you to add more information about what went wrong that will be reported when a test fails. Here's an example:
withClue("(Employee's name was: " + employee.name + ")") {
intercept[IllegalArgumentException] {
employee.getTask(-1)
}
}
If an invocation of intercept completed abruptly with an exception, the resulting message would be something like:
(Employee's name was Bob Jones) Expected IllegalArgumentException to be thrown, but no exception was thrown
NullArgumentException if the passed clue is null
Run the passed test function in the context of a fixture established by this method.
Run the passed test function in the context of a fixture established by this method.
This method should set up the fixture needed by the tests of the
current suite, invoke the test function, and if needed, perform any clean
up needed after the test completes. Because the NoArgTest function
passed to this method takes no parameters, preparing the fixture will require
side effects, such as reassigning instance vars in this Suite or initializing
a globally accessible external database. If you want to avoid reassigning instance vars
you can use fixture.Suite.
This trait's implementation of runTest invokes this method for each test, passing
in a NoArgTest whose apply method will execute the code of the test.
This trait's implementation of this method simply invokes the passed NoArgTest function.
the no-arg test function to run with a fixture
Facilitates a “behavior-driven” style of development (BDD), in which tests are methods, optionally nested inside singleton objects defining textual scopes.
Specallows you to define tests as methods, which saves one function literal per test compared to style classes that represent tests as functions. Fewer function literals translates into faster compile times and fewer generated class files, which can help minimize build times. As a result, usingSpeccan be a good choice in large projects where build times are a concern as well as when generating large numbers of tests programatically via static code generators.Here's an example
Spec:package org.scalatest.examples.spec import org.scalatest.Spec class SetSpec extends Spec { object `A Set` { object `when empty` { def `should have size 0` { assert(Set.empty.size === 0) } def `should produce NoSuchElementException when head is invoked` { intercept[NoSuchElementException] { Set.empty.head } } } } }A
Speccan contain scopes and tests. You define a scope with a nested singleton object, and a test with a method. The names of both scope objects and test methods must be expressed in back ticks and contain at least one space character.A space placed in backticks is encoded by the Scala compiler as
$u0020, as illustrated here:Specuses reflection to discover scope objects and test methods. During discovery,Specwill consider any nested singleton object whose name includes$u0020a scope object, and any method whose name includes$u0020a test method. It will ignore any singleton objects or methods that do not include a$u0020character. Thus,Specwould not consider the following singleton object a scope object:object `Set` { // Not discovered, because no space character }You can make such a scope discoverable by placing a space at the end, like this:
object `Set ` { // Discovered, because of the trailing space character }Rather than performing this discovery during construction, when instance variables used by scope objects may as yet be uninitialized,
Specperforms discovery lazily, the first time a method needing the results of discovery is invoked. For example, methodsrun,runTests,tags,expectedTestCount,runTest, andtestNamesall ensure that scopes and tests have already been discovered prior to doing anything else. Discovery is performed, and the results recorded, only once for eachSpecinstance.A scope names, or gives more information about, the subject (class or other entity) you are specifying and testing. In the previous example,
`A Set`is the subject under specification and test. With each test name you provide a string (the test text) that specifies one bit of behavior of the subject, and a block of code (the body of the test method) that verifies that behavior.When you execute a
Spec, it will sendFormatters in the events it sends to theReporter. ScalaTest's built-in reporters will report these events in such a way that the output is easy to read as an informal specification of the subject being tested. For example, were you to runSetSpecfrom within the Scala interpreter:You would see:
Or, to run just the test named
A Set when empty should have size 0, you could pass that test's name, or any unique substring of the name, such as"size 0"or even just"0". Here's an example:You can also pass to
executea config map of key-value pairs, which will be passed down into suites and tests, as well as other parameters that configure the run itself. For more information on running in the Scala interpreter, see the documentation for the ScalaTest shell.The
executemethod invokes arunmethod that takes two parameters. Thisrunmethod, which actually executes the suite, will usually be invoked by a test runner, such asrun,tools.Runner, a build tool, or an IDE.The test methods shown in this example are parameterless. This is recommended even for test methods with obvious side effects. In production code you would normally declare no-arg, side-effecting methods as empty-paren methods, and call them with empty parentheses, to make it more obvious to readers of the code that they have a side effect. Whether or not a test method has a side effect, however, is a less important distinction than it is for methods in production code. Moreover, test methods are not normally invoked directly by client code, but rather through reflection by running the
Suitethat contains them, so a lack of parentheses on an invocation of a side-effecting test method would not normally appear in any client code. Given the empty parentheses do not add much value in the test methods case, the recommended style is to simply always leave them off.Note: The approach of using backticks around test method names to make it easier to write descriptive test names was inspired by the
SimpleSpectest framework, originally created by Coda Hale.Ignored tests
To support the common use case of temporarily disabling a test in a
Spec, with the good intention of resurrecting the test at a later time, you can annotate the test method with@Ignore. For example, to temporarily disable the test method with the name`should have size zero", just annotate it with@Ignore, like this:package org.scalatest.examples.spec.ignore import org.scalatest._ class SetSpec extends Spec { object `A Set` { object `when empty` { @Ignore def `should have size 0` { assert(Set.empty.size === 0) } def `should produce NoSuchElementException when head is invoked` { intercept[NoSuchElementException] { Set.empty.head } } } } }If you run this version ofSetSpecwith: It will run only the second test and report that the first test was ignored: If you wish to temporarily ignore an entire suite of tests, you can annotate the test class with@Ignore, like this:package org.scalatest.examples.spec.ignoreall import org.scalatest._ @Ignore class SetSpec extends Spec { object `A Set` { object `when empty` { def `should have size 0` { assert(Set.empty.size === 0) } def `should produce NoSuchElementException when head is invoked` { intercept[NoSuchElementException] { Set.empty.head } } } } }When you mark a test class with a tag annotation, ScalaTest will mark each test defined in that class with that tag. Thus, marking theSetSpecin the above example with the@Ignoretag annotation means that both tests in the class will be ignored. If you run the aboveSetSpecin the Scala interpreter, you'll see: Note that marking a test class as ignored won't prevent it from being discovered by ScalaTest. Ignored classes will be discovered and run, and all their tests will be reported as ignored. This is intended to keep the ignored class visible, to encourage the developers to eventually fix and “un-ignore” it. If you want to prevent a class from being discovered at all, use theDoNotDiscoverannotation instead. == Informers ==One of the objects to
Spec'srunmethod is aReporter, 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 theReporteras the suite runs. Most often the reporting done by default bySpec's methods will be sufficient, but occasionally you may wish to provide custom information to theReporterfrom a test. For this purpose, anInformerthat will forward information to the currentReporteris provided via theinfoparameterless method. You can pass the extra information to theInformervia one of itsapplymethods. TheInformerwill then pass the information to theReportervia anInfoProvidedevent. Here's an example in which theInformerreturned byinfois used implicitly by theGiven,When, andThenmethods of traitGivenWhenThen:package org.scalatest.examples.spec.info import collection.mutable import org.scalatest._ class SetSpec extends Spec with GivenWhenThen { object `A mutable Set` { def `should allow an element to be added` { Given("an empty mutable Set") val set = mutable.Set.empty[String] When("an element is added") set += "clarity" Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains("clarity")) info("That's all folks!") } } }If you run this
Specfrom the interpreter, you will see the following output:scala> new SetSpec execute A mutable Set - should allow an element to be added + Given an empty mutable Set + When an element is added + Then the Set should have size 1 + And the Set should contain the added element + That's all folks!Documenters
Specalso provides amarkupmethod that returns aDocumenter, which allows you to send to theReportertext formatted in Markdown syntax. You can pass the extra information to theDocumentervia itsapplymethod. TheDocumenterwill then pass the information to theReportervia anMarkupProvidedevent. Here's an exampleSpecthat usesmarkup:package org.scalatest.examples.spec.markup import collection.mutable import org.scalatest._ class SetSpec extends Spec with GivenWhenThen { markup { """ Mutable Set ----------- A set is a collection that contains no duplicate elements. To implement a concrete mutable set, you need to provide implementations of the following methods: def contains(elem: A): Boolean def iterator: Iterator[A] def += (elem: A): this.type def -= (elem: A): this.type If you wish that methods like `take`, `drop`, `filter` return the same kind of set, you should also override: def empty: This It is also good idea to override methods `foreach` and `size` for efficiency. """ } object `A mutable Set` { def `should allow an element to be added` { Given("an empty mutable Set") val set = mutable.Set.empty[String] When("an element is added") set += "clarity" Then("the Set should have size 1") assert(set.size === 1) And("the Set should contain the added element") assert(set.contains("clarity")) markup("This test finished with a **bold** statement!") } } }Although all of ScalaTest's built-in reporters will display the markup text in some form, the HTML reporter will format the markup information into HTML. Thus, the main purpose ofmarkupis to add nicely formatted text to HTML reports. Here's what the aboveSetSpecwould look like in the HTML reporter:infoandmarkupduring tests, and sends the recorded text in therecordedEventsfield of test completion events likeTestSucceededandTestFailed. This allows string reporters (like the standard out reporter) to showinfoandmarkuptext after the test name in a color determined by the outcome of the test. For example, if the test fails, string reporters will show theinfoandmarkuptext in red. If a test succeeds, string reporters will show theinfoandmarkuptext in green. While this approach helps the readability of reports, it means that you can't useinfoto get status updates from long running tests. To get immediate (i.e., non-recorded) notifications from tests, you can usenote(aNotifier) andalert(anAlerter). Here's an example showing the differences:package org.scalatest.examples.spec.note import collection.mutable import org.scalatest._ class SetSpec extends Spec { object `A mutable Set` { def `should allow an element to be added` { info("info is recorded") markup("markup is *also* recorded") note("notes are sent immediately") alert("alerts are also sent immediately") val set = mutable.Set.empty[String] set += "clarity" assert(set.size === 1) assert(set.contains("clarity")) } } }Becausenoteandalertinformation is sent immediately, it will appear before the test name in string reporters, and its color will be unrelated to the ultimate outcome of the test:notetext will always appear in green,alerttext will always appear in yellow. Here's an example: In summary, useinfoandmarkupfor text that should form part of the specification output. Usenoteandalertto send status notifications. (Because the HTML reporter is intended to produce a readable, printable specification,infoandmarkuptext will appear in the HTML report, butnoteandalerttext will not.) == Pending tests == A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later. To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. The test can also include some code that sends more information about the behavior to the reporter when the tests run. At the end of the test, it can call methodpending, which will cause it to complete abruptly withTestPendingException. Because tests in ScalaTest can be designated as pending withTestPendingException, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (The code of a pending test is executed just like any other test.) However, because the test completes abruptly withTestPendingException, the test will be reported as pending, to indicate the actual test, and possibly the functionality, has not yet been implemented. You can mark a test as pending inSpecby using "{ pending }" as the body of the test method, like this:package org.scalatest.examples.spec.pending import org.scalatest._ class SetSpec extends Spec { object `A Set` { object `when empty` { def `should have size 0` { pending } def `should produce NoSuchElementException when head is invoked` { intercept[NoSuchElementException] { Set.empty.head } } } } }(Note: “pending” is the body of the test. Thus the test contains just one statement, an invocation of thependingmethod, which throwsTestPendingException.) If you run this version ofSetSpecwith: It will run both tests, but report that test "should have size 0" is pending. You'll see: == Tagging tests == ASpec's tests may be classified into groups by tagging them with string names. When executing aSpec, 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 inSpecs, simply define a new Java annotation that itself is annotated with theorg.scalatest.TagAnnotationannotation. (Currently, for annotations to be visible in Scala programs via Java reflection, the annotations themselves must be written in Java.) For example, to create tags namedSlowTestandDbTest, you would write in Java:package org.scalatest.examples.spec.tagging; import java.lang.annotation.*; import org.scalatest.TagAnnotation; @TagAnnotation @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD, ElementType.TYPE}) public @interface SlowTest {} @TagAnnotation @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD, ElementType.TYPE}) public @interface DbTest {}Given these annotations, you could tagSpectests like this:package org.scalatest.examples.spec.tagging import org.scalatest.Spec class SetSpec extends Spec { object `A Set` { object `when empty` { @SlowTest def `should have size 0` { assert(Set.empty.size === 0) } @SlowTest @DbTest def `should produce NoSuchElementException when head is invoked` { intercept[NoSuchElementException] { Set.empty.head } } } } }Therunmethod takes aFilter, whose constructor takes an optionalSet[String]calledtagsToIncludeand aSet[String]calledtagsToExclude. IftagsToIncludeisNone, all tests will be run except those those with tags listed in thetagsToExcludeSet. IftagsToIncludeis defined, only tests with tags mentioned in thetagsToIncludeset, and not mentioned intagsToExclude, will be run. A tag annotation also allows you to tag all the tests of aSpecin one stroke by annotating the class. For more information and examples, see the documentation for classTag. == Shared fixtures == A test fixture is composed of the objects and other artifacts (files, sockets, database connections, etc.) tests use to do their work. When multiple tests need to work with the same fixtures, it is important to try and avoid duplicating the fixture code across those tests. The more code duplication you have in your tests, the greater drag the tests will have on refactoring the actual production code. ScalaTest recommends three techniques to eliminate such code duplication: - Refactor using Scala - OverridewithFixture- Mix in a before-and-after trait Each technique is geared towards helping you reduce code duplication without introducing instancevars, shared mutable objects, or other dependencies between tests. Eliminating shared mutable state across tests will make your test code easier to reason about and more amenable for parallel test execution. The following sections describe these techniques, including explaining the recommended usage for each. But first, here's a table summarizing the options:withFixturewhen most or all tests need the same fixture.withFixture(NoArgTest)withFixture(OneArgTest)instead)withFixture(OneArgTest)BeforeAndAfterBeforeAndAfterEachpackage org.scalatest.examples.spec.getfixture import org.scalatest.Spec import collection.mutable.ListBuffer class ExampleSpec extends Spec { def fixture = new { val builder = new StringBuilder("ScalaTest is ") val buffer = new ListBuffer[String] } object `Testing ` { def `should be easy` { val f = fixture f.builder.append("easy!") assert(f.builder.toString === "ScalaTest is easy!") assert(f.buffer.isEmpty) f.buffer += "sweet" } def `should be fun` { val f = fixture f.builder.append("fun!") assert(f.builder.toString === "ScalaTest is fun!") assert(f.buffer.isEmpty) } } }The “f.” in front of each use of a fixture object provides a visual indication of which objects are part of the fixture, but if you prefer, you can import the the members with “import f._” and use the names directly. If you need to configure fixture objects differently in different tests, you can pass configuration into the get-fixture method. For example, you could pass in an initial value for a mutable fixture object as a parameter to the get-fixture method. ==== Instantiating fixture-context objects ==== An alternate technique that is especially useful when different tests need different combinations of fixture objects is to define the fixture objects as instance variables of fixture-context objects whose instantiation forms the body of tests. Like get-fixture methods, fixture-context objects are only appropriate if you don't need to clean up the fixtures after using them. To use this technique, you define instance variables intialized with fixture objects in traits and/or classes, then in each test instantiate an object that contains just the fixture objects needed by the test. Traits allow you to mix together just the fixture objects needed by each test, whereas classes allow you to pass data in via a constructor to configure the fixture objects. Here's an example in which fixture objects are partitioned into two traits and each test just mixes together the traits it needs:package org.scalatest.examples.spec.fixturecontext import collection.mutable.ListBuffer import org.scalatest.Spec class ExampleSpec extends Spec { trait Builder { val builder = new StringBuilder("ScalaTest is ") } trait Buffer { val buffer = ListBuffer("ScalaTest", "is") } object `Testing ` { // This test needs the StringBuilder fixture def `should be productive` { new Builder { builder.append("productive!") assert(builder.toString === "ScalaTest is productive!") } } } object `Test code` { // This test needs the ListBuffer[String] fixture def `should be readable` { new Buffer { buffer += ("readable!") assert(buffer === List("ScalaTest", "is", "readable!")) } } // This test needs both the StringBuilder and ListBuffer def `should be clear and concise` { new Builder with Buffer { builder.append("clear!") buffer += ("concise!") assert(builder.toString === "ScalaTest is clear!") assert(buffer === List("ScalaTest", "is", "concise!")) } } } }==== OverridingwithFixture(NoArgTest)==== Although the get-fixture method and fixture-context object approaches take care of setting up a fixture at the beginning of each test, they don't address the problem of cleaning up a fixture at the end of the test. If you just need to perform a side-effect at the beginning or end of a test, and don't need to actually pass any fixture objects into the test, you can overridewithFixture(NoArgTest), one of ScalaTest's lifecycle methods defined in traitSuite. TraitSuite's implementation ofrunTestpasses a no-arg test function towithFixture(NoArgTest). It iswithFixture's responsibility to invoke that test function.Suite's implementation ofwithFixturesimply invokes the function, like this:// Default implementation in trait Suite protected def withFixture(test: NoArgTest) = { test() }You can, therefore, overridewithFixtureto perform setup before and/or cleanup after invoking the test function. If you have cleanup to perform, you should invoke the test function inside atryblock and perform the cleanup in afinallyclause, in case an exception propagates back throughwithFixture. (If a test fails because of an exception, the test function invoked by withFixture will result in a [[org.scalatest.FailedFailed]] wrapping the exception. Nevertheless, best practice is to perform cleanup in a finally clause just in case an exception occurs.) ThewithFixturemethod is designed to be stacked, and to enable this, you should always call thesuperimplementation ofwithFixture, and let it invoke the test function rather than invoking the test function directly. In other words, instead of writing “test()”, you should write “super.withFixture(test)”, like this:// Your implementation override def withFixture(test: NoArgTest) = { // Perform setup try super.withFixture(test) // Invoke the test function finally { // Perform cleanup } }Here's an example in whichwithFixture(NoArgTest)is used to take a snapshot of the working directory if a test fails, and and send that information to the reporter:package org.scalatest.examples.spec.noargtest import java.io.File import org.scalatest._ class ExampleSpec extends Spec { override def withFixture(test: NoArgTest) = { super.withFixture(test) match { case failed: Failed => val currDir = new File(".") val fileNames = currDir.list() info("Dir snapshot: " + fileNames.mkString(", ")) failed case other => other } } object `This test` { def `should succeed` { assert(1 + 1 === 2) } def `should fail` { assert(1 + 1 === 3) } } }Running this version ofExampleSuitein the interpreter in a directory with two files,hello.txtandworld.txtwould give the following output:scala> new ExampleSuite execute ExampleSuite: This test - should fail *** FAILED *** 2 did not equal 3 (:33)
+ Dir snapshot: hello.txt, world.txt
- should succeed
Note that theNoArgTestpassed towithFixture, in addition to anapplymethod that executes the test, also includes the test name and the config map passed torunTest. Thus you can also use the test name and configuration objects in yourwithFixtureimplementation. ==== Calling loan-fixture methods ==== If you need to both pass a fixture object into a test and perform cleanup at the end of the test, you'll need to use the loan pattern. If different tests need different fixtures that require cleanup, you can implement the loan pattern directly by writing loan-fixture methods. A loan-fixture method takes a function whose body forms part or all of a test's code. It creates a fixture, passes it to the test code by invoking the function, then cleans up the fixture after the function returns. The following example shows three tests that use two fixtures, a database and a file. Both require cleanup after, so each is provided via a loan-fixture method. (In this example, the database is simulated with aStringBuffer.)package org.scalatest.examples.spec.loanfixture import java.util.concurrent.ConcurrentHashMap object DbServer { // Simulating a database server type Db = StringBuffer private val databases = new ConcurrentHashMap[String, Db] def createDb(name: String): Db = { val db = new StringBuffer databases.put(name, db) db } def removeDb(name: String) { databases.remove(name) } } import org.scalatest.Spec import DbServer._ import java.util.UUID.randomUUID import java.io._ class ExampleSpec extends Spec { def withDatabase(testCode: Db => Any) { val dbName = randomUUID.toString val db = createDb(dbName) // create the fixture try { db.append("ScalaTest is ") // perform setup testCode(db) // "loan" the fixture to the test } finally removeDb(dbName) // clean up the fixture } def withFile(testCode: (File, FileWriter) => Any) { val file = File.createTempFile("hello", "world") // create the fixture val writer = new FileWriter(file) try { writer.write("ScalaTest is ") // set up the fixture testCode(file, writer) // "loan" the fixture to the test } finally writer.close() // clean up the fixture } object `Testing ` { // This test needs the file fixture def `should be productive` { withFile { (file, writer) => writer.write("productive!") writer.flush() assert(file.length === 24) } } } object `Test code` { // This test needs the database fixture def `should be readable` { withDatabase { db => db.append("readable!") assert(db.toString === "ScalaTest is readable!") } } // This test needs both the file and the database def `should be clear and concise` { withDatabase { db => withFile { (file, writer) => // loan-fixture methods compose db.append("clear!") writer.write("concise!") writer.flush() assert(db.toString === "ScalaTest is clear!") assert(file.length === 21) } } } } }As demonstrated by the last test, loan-fixture methods compose. Not only do loan-fixture methods allow you to give each test the fixture it needs, they allow you to give a test multiple fixtures and clean everything up afterwards. Also demonstrated in this example is the technique of giving each test its own "fixture sandbox" to play in. When your fixtures involve external side-effects, like creating files or databases, it is a good idea to give each file or database a unique name as is done in this example. This keeps tests completely isolated, allowing you to run them in parallel if desired. ==== OverridingwithFixture(OneArgTest)==== If all or most tests need the same fixture, you can avoid some of the boilerplate of the loan-fixture method approach by using afixture.Specand overridingwithFixture(OneArgTest). Each test in afixture.Spectakes a fixture as a parameter, allowing you to pass the fixture into the test. You must indicate the type of the fixture parameter by specifyingFixtureParam, and implement awithFixturemethod that takes aOneArgTest. ThiswithFixturemethod is responsible for invoking the one-arg test function, so you can perform fixture set up before, and clean up after, invoking and passing the fixture into the test function. To enable the stacking of traits that definewithFixture(NoArgTest), it is a good idea to letwithFixture(NoArgTest)invoke the test function instead of invoking the test function directly. To do so, you'll need to convert theOneArgTestto aNoArgTest. You can do that by passing the fixture object to thetoNoArgTestmethod ofOneArgTest. In other words, instead of writing “test(theFixture)”, you'd delegate responsibility for invoking the test function to thewithFixture(NoArgTest)method of the same instance by writing: Here's a complete example:package org.scalatest.examples.spec.oneargtest import org.scalatest.fixture import java.io._ class ExampleSpec extends fixture.Spec { case class FixtureParam(file: File, writer: FileWriter) def withFixture(test: OneArgTest) = { // create the fixture val file = File.createTempFile("hello", "world") val writer = new FileWriter(file) val theFixture = FixtureParam(file, writer) try { writer.write("ScalaTest is ") // set up the fixture withFixture(test.toNoArgTest(theFixture)) // "loan" the fixture to the test } finally writer.close() // clean up the fixture } object `Testing ` { def `should be easy` { f: FixtureParam => f.writer.write("easy!") f.writer.flush() assert(f.file.length === 18) } def `should be fun` { f: FixtureParam => f.writer.write("fun!") f.writer.flush() assert(f.file.length === 17) } } }In this example, the tests actually required two fixture objects, aFileand aFileWriter. In such situations you can simply define theFixtureParamtype to be a tuple containing the objects, or as is done in this example, a case class containing the objects. For more information on thewithFixture(OneArgTest)technique, see the documentation forfixture.Spec. ==== Mixing inBeforeAndAfter==== In all the shared fixture examples shown so far, the activities of creating, setting up, and cleaning up the fixture objects have been performed during the test. This means that if an exception occurs during any of these activities, it will be reported as a test failure. Sometimes, however, you may want setup to happen before the test starts, and cleanup after the test has completed, so that if an exception occurs during setup or cleanup, the entire suite aborts and no more tests are attempted. The simplest way to accomplish this in ScalaTest is to mix in traitBeforeAndAfter. With this trait you can denote a bit of code to run before each test withbeforeand/or after each test each test withafter, like this:package org.scalatest.examples.spec.beforeandafter import org.scalatest.Spec import org.scalatest.BeforeAndAfter import collection.mutable.ListBuffer class ExampleSpec extends Spec with BeforeAndAfter { val builder = new StringBuilder val buffer = new ListBuffer[String] before { builder.append("ScalaTest is ") } after { builder.clear() buffer.clear() } object `Testing ` { def `should be easy` { builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(buffer.isEmpty) buffer += "sweet" } def `should be fun` { builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(buffer.isEmpty) } } }Note that the only waybeforeandaftercode can communicate with test code is via some side-effecting mechanism, commonly by reassigning instancevars or by changing the state of mutable objects held from instancevals (as in this example). If using instancevars or mutable objects held from instancevals you wouldn't be able to run tests in parallel in the same instance of the test class unless you synchronized access to the shared, mutable state. This is why ScalaTest'sParallelTestExecutiontrait extendsOneInstancePerTest. By running each test in its own instance of the class, each test has its own copy of the instance variables, so you don't need to synchronize. If you mixedParallelTestExecutioninto theExampleSuiteabove, the tests would run in parallel just fine without any synchronization needed on the mutableStringBuilderandListBuffer[String]objects. AlthoughBeforeAndAfterprovides a minimal-boilerplate way to execute code before and after tests, it isn't designed to enable stackable traits, because the order of execution would be non-obvious. If you want to factor out before and after code that is common to multiple test suites, you should use traitBeforeAndAfterEachinstead, as shown later in the next section, composing fixtures by stacking traits. == Composing fixtures by stacking traits == In larger projects, teams often end up with several different fixtures that test classes need in different combinations, and possibly initialized (and cleaned up) in different orders. A good way to accomplish this in ScalaTest is to factor the individual fixtures into traits that can be composed using the stackable trait pattern. This can be done, for example, by placingwithFixturemethods in several traits, each of which callsuper.withFixture. Here's an example in which theStringBuilderandListBuffer[String]fixtures used in the previous examples have been factored out into two stackable fixture traits namedBuilderandBuffer:package org.scalatest.examples.spec.composingwithfixture import org.scalatest._ import collection.mutable.ListBuffer trait Builder extends SuiteMixin { this: Suite => val builder = new StringBuilder abstract override def withFixture(test: NoArgTest) = { builder.append("ScalaTest is ") try super.withFixture(test) // To be stackable, must call super.withFixture finally builder.clear() } } trait Buffer extends SuiteMixin { this: Suite => val buffer = new ListBuffer[String] abstract override def withFixture(test: NoArgTest) = { try super.withFixture(test) // To be stackable, must call super.withFixture finally buffer.clear() } } class ExampleSpec extends Spec with Builder with Buffer { object `Testing ` { def `should be easy` { builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(buffer.isEmpty) buffer += "sweet" } def `should be fun` { builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(buffer.isEmpty) buffer += "clear" } } }By mixing in both theBuilderandBuffertraits,ExampleSpecgets both fixtures, which will be initialized before each test and cleaned up after. The order the traits are mixed together determines the order of execution. In this case,Builderis “super” toBuffer. If you wantedBufferto be “super” toBuilder, you need only switch the order you mix them together, like this: And if you only need one fixture you mix in only that trait: Another way to create stackable fixture traits is by extending theBeforeAndAfterEachand/orBeforeAndAfterAlltraits.BeforeAndAfterEachhas abeforeEachmethod that will be run before each test (like JUnit'ssetUp), and anafterEachmethod that will be run after (like JUnit'stearDown). Similarly,BeforeAndAfterAllhas abeforeAllmethod that will be run before all tests, and anafterAllmethod that will be run after all tests. Here's what the previously shown example would look like if it were rewritten to use theBeforeAndAfterEachmethods instead ofwithFixture:package org.scalatest.examples.spec.composingbeforeandaftereach import org.scalatest._ import org.scalatest.BeforeAndAfterEach import collection.mutable.ListBuffer trait Builder extends BeforeAndAfterEach { this: Suite => val builder = new StringBuilder override def beforeEach() { builder.append("ScalaTest is ") super.beforeEach() // To be stackable, must call super.beforeEach } override def afterEach() { try super.afterEach() // To be stackable, must call super.afterEach finally builder.clear() } } trait Buffer extends BeforeAndAfterEach { this: Suite => val buffer = new ListBuffer[String] override def afterEach() { try super.afterEach() // To be stackable, must call super.afterEach finally buffer.clear() } } class ExampleSpec extends Spec with Builder with Buffer { object `Testing ` { def `should be easy` { builder.append("easy!") assert(builder.toString === "ScalaTest is easy!") assert(buffer.isEmpty) buffer += "sweet" } def `should be fun` { builder.append("fun!") assert(builder.toString === "ScalaTest is fun!") assert(buffer.isEmpty) buffer += "clear" } } }To get the same ordering aswithFixture, place yoursuper.beforeEachcall at the end of eachbeforeEachmethod, and thesuper.afterEachcall at the beginning of eachafterEachmethod, as shown in the previous example. It is a good idea to invokesuper.afterEachin atryblock and perform cleanup in afinallyclause, as shown in the previous example, because this ensures the cleanup code is performed even ifsuper.afterEachthrows an exception. The difference between stacking traits that extendBeforeAndAfterEachversus traits that implementwithFixtureis that setup and cleanup code happens before and after the test inBeforeAndAfterEach, but at the beginning and end of the test inwithFixture. Thus if awithFixturemethod completes abruptly with an exception, it is considered a failed test. By contrast, if any of thebeforeEachorafterEachmethods ofBeforeAndAfterEachcomplete abruptly, it is considered an aborted suite, which will result in aSuiteAbortedevent. == Shared tests == BecauseSpecrepresents tests as methods, you cannot share or otherwise dynamically generate tests. Instead, use static code generation if you want to generate tests in aSpec. In other words, write a program that statically generates the entire source file of aSpecsubclass.