A sister class to org.scalatest.FunSpec
that isolates tests by running each test in its own
instance of the test class, and for each test, only executing the path leading to that test.
Implementation trait for class path.FunSpec
, which is
a sister class to org.scalatest.FunSpec
that isolates
tests by running each test in its own instance of the test class,
and for each test, only executing the path leading to that test.
Implementation trait for class path.FunSpec
, which is
a sister class to org.scalatest.FunSpec
that isolates
tests by running each test in its own instance of the test class,
and for each test, only executing the path leading to that test.
path.FunSpec
is a class, not a trait,
to minimize compile time given there is a slight compiler overhead to
mixing in traits compared to extending classes. If you need to mix the
behavior of path.FunSpec
into some other class, you can use this
trait instead, because class path.FunSpec
does nothing more than
extend this trait and add a nice toString
implementation.
See the documentation of the class for a detailed
overview of path.FunSpec
.
A sister class to
org.scalatest.FunSpec
that isolates tests by running each test in its own instance of the test class, and for each test, only executing the path leading to that test.Class
path.FunSpec
behaves similarly to classorg.scalatest.FunSpec
, except that tests are isolated based on their path. The purpose ofpath.FunSpec
is to facilitate writing specification-style tests for mutable objects in a clear, boilerpate-free way. To test mutable objects, you need to mutate them. Using a path class, you can make a statement in text, then implement that statement in code (including mutating state), and nest and combine these test/code pairs in any way you wish. Each test will only see the side effects of code that is in blocks that enclose the test. Here's an example:Note that the above class is organized by writing a bit of specification text that opens a new block followed by, at the top of the new block, some code that "implements" or "performs" what is described in the text. This is repeated as the mutable object (here, a
ListBuffer
), is prepared for the enclosed tests. For example:Or:
Note also that although each test mutates the
ListBuffer
, none of the other tests observe those side effects:This kind of isolation of tests from each other is a consequence of running each test in its own instance of the test class, and can also be achieved by simply mixing
OneInstancePerTest
into a regularorg.scalatest.FunSpec
. However,path.FunSpec
takes isolation one step further: a test in apath.FunSpec
does not observe side effects performed outside tests in earlier blocks that do not enclose it. Here's an example:Running the full
ExampleSpec
, shown above, in the Scala interpeter would give you:scala> import org.scalatest._ import org.scalatest._ scala> run(new ExampleSpec) ExampleSpec: A ListBuffer - should be empty when created when 1 is appended - should contain 1 when 2 is appended - should contain 1 and 2 when 2 is removed - should contain only 1 again when 3 is appended - should contain 1, 2, and 3 when 88 is appended - should contain 1 and 88 - should have size 0 when created
Note: class
path.FunSpec
's approach to isolation was inspired in part by the specsy framework, written by Esko Luontola.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, then the definitions of the fixture objects can be local to the method. If multiple tests need to share an immutable fixture, you can simply assign them to instance variables. If multiple tests need to share mutable fixture objects or
var
s, there's one and only one way to do it in apath.FunSpec
: place the mutable objects lexically before the test. Any mutations needed by the test must be placed lexically before and/or after the test. As used here, "Lexically before" means that the code needs to be executed during construction of that test's instance of the test class to reach the test (or put another way, the code is along the "path to the test.") "Lexically after" means that the code needs to be executed to exit the constructor after the test has been executed.The reason lexical placement is the one and only one way to share fixtures in a
path.FunSpec
is because all of its lifecycle methods are overridden and declaredfinal
. Thus you can't overridewithFixture
, because it isfinal
, or mix inBeforeAndAfter
orBeforeAndAfterEach
, because both overriderunTest
, which isfinal
in apath.FunSpec
. In short:path.FunSpec
, if you need some code to execute before a test, place that code lexically before the test. If you need some code to execute after a test, place that code lexically after the test.The reason the life cycle methods are final, by the way, is to prevent users from attempting to combine a
path.FunSpec
's approach to isolation with other ways ScalaTest provides to share fixtures or execute tests, because doing so could make the resulting test code hard to reason about. Apath.FunSpec
's execution model is a bit magical, but because it executes in one and only one way, users should be able to reason about the code. To help you visualize how apath.FunSpec
is executed, consider the following variant ofExampleSpec
that includes print statements:Running the above version of
ExampleSpec
in the Scala interpreter will give you output similar to:Note that each test is executed in order of appearance in the
path.FunSpec
, and that only thoseprintln
statements residing in blocks that enclose the test being run are executed. Anyprintln
statements in blocks that do not form the "path" to a test are not executed in the instance of the class that executes that test.== How it executes == To provide its special brand of test isolation,
However, an empty scope (a scope that contains no tests or nested scopes) is also a leaf node: The tests will be executed sequentially, in the order of appearance. The first test (or empty scope, if that is first) will be executed when a class that mixes inpath.FunSpec
executes quite differently from its sister class inorg.scalatest
. Anorg.scalatest.FunSpec
registers tests during construction and executes them whenrun
is invoked. Anorg.scalatest.path.FunSpec
, by contrast, runs each test in its own instance while that instance is being constructed. During construction, it registers not the tests to run, but the results of running those tests. Whenrun
is invoked on apath.FunSpec
, it reports the registered results and does not run the tests again. Ifrun
is invoked a second or third time, in fact, apath.FunSpec
will each time report the same results registered during construction. If you want to run the tests of apath.FunSpec
anew, you'll need to create a new instance and invokerun
on that. Apath.FunSpec
will create one instance for each "leaf" node it contains. The main kind of leaf node is a test, such as:path.FunSpec
is instantiated. Only the first test will be executed during this initial instance, and of course, only the path to that test. Then, the first time the client uses the initial instance (by invoking one ofrun
,expectedTestsCount
,tags
, ortestNames
on the instance), the initial instance will, before doing anything else, ensure that any remaining tests are executed, each in its own instance. To ensure that the correct path is taken in each instance, and to register its test results, the initialpath.FunSpec
instance must communicate with the other instances it creates for running any subsequent leaf nodes. It does so by setting a thread-local variable prior to creating each instance (a technique suggested by Esko Luontola). Each instance ofpath.FunSpec
checks the thread-local variable. If the thread-local is not set, it knows it is an initial instance and therefore executes every block it encounters until it discovers, and executes the first test (or empty scope, if that's the first leaf node). It then discovers, but does not execute the next leaf node, or discovers there are no other leaf nodes remaining to execute. It communicates the path to the next leaf node, if any, and the result of running the test it did execute, if any, back to the initial instance. The initial instance repeats this process until all leaf nodes have been executed and all test results registered. == Ignored tests == You mark a test as ignored in anorg.scalatest.path.FunSpec
in the same manner as in anorg.scalatest.FunSpec
. Please see the Ignored tests section in its documentation for more information. Note that a separate instance will be created for an ignored test, and the path to the ignored test will be executed in that instance, but the test function itself will not be executed. Instead, aTestIgnored
event will be fired. == Informers == You output information usingInformer
s in anorg.scalatest.path.FunSpec
in the same manner as in anorg.scalatest.FunSpec
. Please see the Informers section in its documentation for more information. == Pending tests == You mark a test as pending in anorg.scalatest.path.FunSpec
in the same manner as in anorg.scalatest.FunSpec
. Please see the Pending tests section in its documentation for more information. Note that a separate instance will be created for a pending test, and the path to the ignored test will be executed in that instance, as well as the test function (up until it completes abruptly with aTestPendingException
). == Tagging tests == You can place tests into groups by tagging them in anorg.scalatest.path.FunSpec
in the same manner as in anorg.scalatest.FunSpec
. Please see the Tagging tests section in its documentation for more information. Note that one difference between this class and its sister classorg.scalatest.FunSpec
is that because tests are executed at construction time, rather than each time run is invoked, anorg.scalatest.path.FunSpec
will always execute all non-ignored tests. Whenrun
is invoked on apath.FunSpec
, if some tests are excluded based on tags, the registered results of running those tests will not be reported. (But those tests will have already run and the results registered.) By contrast, because anorg.scalatest.FunSpec
only executes tests afterrun
has been called, and at that time the tags to include and exclude are known, only tests selected by the tags will be executed. In short, in anorg.scalatest.FunSpec
, tests not selected by the tags to include and exclude specified for the run (via theFilter
passed torun
) will not be executed. In anorg.scalatest.path.FunSpec
, by contrast, all non-ignored tests will be executed, each during the construction of its own instance, and tests not selected by the tags to include and exclude specified for a run will not be reported. (One upshot of this is that if you have tests that you want to tag as being slow so you can sometimes exclude them during a run, you probably don't want to put them in apath.FunSpec
. Because in apath.Freespec
the slow tests will be run regardless, with only their registered results not being reported if you exclude slow tests during a run.) == Shared tests == You can factor out shared tests in anorg.scalatest.path.FunSpec
in the same manner as in anorg.scalatest.FunSpec
. Please see the Shared tests section in its documentation for more information. == Nested suites == Nested suites are not allowed in apath.FunSpec
. Because apath.FunSpec
executes tests eagerly at construction time, registering the results of those test runs and reporting them later whenrun
is invoked, the order of nested suites versus test runs would be different in aorg.scalatest.path.FunSpec
than in anorg.scalatest.FunSpec
. Inorg.scalatest.FunSpec
's implementation ofrun
, nested suites are executed then tests are executed. Aorg.scalatest.path.FunSpec
with nested suites would execute these in the opposite order: first tests then nested suites. To help makepath.FunSpec
code easier to reason about by giving readers of one less difference to think about, nested suites are not allowed. If you want to add nested suites to apath.FunSpec
, you can instead wrap them all in aSuites
object. They will be executed in the order of appearance (unless a Distributor is passed, in which case they will execute in parallel). == Durations == Many ScalaTest events include a duration that indicates how long the event being reported took to execute. For example, aTestSucceeded
event provides a duration indicating how long it took for that test to execute. ASuiteCompleted
event provides a duration indicating how long it took for that entire suite of tests to execute. In the test completion events fired by apath.FunSpec
(TestSucceeded
,TestFailed
, orTestPending
), the durations reported refer to the time it took for the tests to run. This time is registered with the test results and reported along with the test results each timerun
is invoked. By contrast, the suite completion events fired for apath.FunSpec
represent the amount of time it took to report the registered results. (These events are not fired bypath.FunSpec
, but instead by the entity that invokesrun
on thepath.FunSpec
.) As a result, the total time for running the tests of apath.FunSpec
, calculated by summing the durations of all the individual test completion events, may be greater than the duration reported for executing the entire suite.