The range defaults to JRE. OTHER as the higher border max , which allows usage of half open ranges. The value supplied via the matches attribute will be interpreted as a regular expression. As of JUnit Jupiter 5. Consequently, these annotations may be declared multiple times on a test interface, test class, or test method. Specifically, these annotations will be found if they are directly present, indirectly present, or meta-present on a given element.
A container or test may be enabled or disabled based on the value of the named environment variable from the underlying operating system via the EnabledIfEnvironmentVariable and DisabledIfEnvironmentVariable annotations. A container or test may be enabled or disabled based on the boolean return of a method via the EnabledIf and DisabledIf annotations.
The method is provided to the annotation via its name. If needed, the condition method can take a single parameter of type ExtensionContext.
Alternatively, the condition method can be located outside the test class. In this case, it has to be referenced by its fully qualified name as demonstrated in the following example.
Test classes and methods can be tagged via the Tag annotation. Those tags can later be used to filter test discovery and execution. Please refer to the Tags section for more information about tag support in the JUnit Platform. By default, test classes and methods will be ordered using an algorithm that is deterministic but intentionally nonobvious.
This ensures that subsequent runs of a test suite execute test classes and test methods in the same order, thereby allowing for repeatable builds. To control the order in which test methods are executed, annotate your test class or test interface with TestMethodOrder and specify the desired MethodOrderer implementation. You can implement your own custom MethodOrderer or use one of the following built-in MethodOrderer implementations. DisplayName : sorts test methods alphanumerically based on their display names see display name generation precedence rules.
MethodName : sorts test methods alphanumerically based on their names and formal parameter lists. OrderAnnotation : sorts test methods numerically based on values specified via the Order annotation. Random : orders test methods pseudo-randomly and supports configuration of a custom seed. Alphanumeric : sorts test methods alphanumerically based on their names and formal parameter lists; deprecated in favor of MethodOrderer.
MethodName , to be removed in 6. The following example demonstrates how to guarantee that test methods are executed in the order specified via the Order annotation. Just like for the orderer configured via the TestMethodOrder annotation, the supplied class has to implement the MethodOrderer interface. The default orderer will be used for all tests unless the TestMethodOrder annotation is present on an enclosing test class or test interface. For example, to use the MethodOrderer.
OrderAnnotation method orderer by default, you should set the configuration parameter to the corresponding fully qualified class name e. Similarly, you can specify the fully qualified name of any custom class that implements MethodOrderer.
Although test classes typically should not rely on the order in which they are executed, there are times when it is desirable to enforce a specific test class execution order. You may wish to execute test classes in a random order to ensure there are no accidental dependencies between test classes, or you may wish to order test classes to optimize build time as outlined in the following scenarios.
With parallel execution enabled, run longer tests first: "shortest test plan execution duration" mode. To configure test class execution order globally for the entire test suite, use the junit. The supplied class must implement the ClassOrderer interface. You can implement your own custom ClassOrderer or use one of the following built-in ClassOrderer implementations. ClassName : sorts test classes alphanumerically based on their fully qualified class names.
DisplayName : sorts test classes alphanumerically based on their display names see display name generation precedence rules. OrderAnnotation : sorts test classes numerically based on values specified via the Order annotation.
Random : orders test classes pseudo-randomly and supports configuration of a custom seed. For example, for the Order annotation to be honored on test classes , you should configure the ClassOrderer. OrderAnnotation class orderer using the configuration parameter with the corresponding fully qualified class name e. The configured ClassOrderer will be applied to all top-level test classes including static nested test classes and Nested test classes. To configure test class execution order locally for Nested test classes, declare the TestClassOrder annotation on the enclosing class for the Nested test classes you want to order, and supply a class reference to the ClassOrderer implementation you would like to use directly in the TestClassOrder annotation.
The configured ClassOrderer will be applied recursively to Nested test classes and their Nested test classes. Note that a local TestClassOrder declaration always overrides an inherited TestClassOrder declaration or a ClassOrderer configured globally via the junit. The following example demonstrates how to guarantee that Nested test classes are executed in the order specified via the Order annotation.
In order to allow individual test methods to be executed in isolation and to avoid unexpected side effects due to mutable test instance state, JUnit creates a new instance of each test class before executing each test method see Test Classes and Methods.
This "per-method" test instance lifecycle is the default behavior in JUnit Jupiter and is analogous to all previous versions of JUnit. If you would prefer that JUnit Jupiter execute all test methods on the same test instance, annotate your test class with TestInstance Lifecycle.
When using this mode, a new test instance will be created once per test class. Thus, if your test methods rely on state stored in instance variables, you may need to reset that state in BeforeEach or AfterEach methods.
The "per-class" mode has some additional benefits over the default "per-method" mode. Specifically, with the "per-class" mode it becomes possible to declare BeforeAll and AfterAll on non-static methods as well as on interface default methods. The "per-class" mode therefore also makes it possible to use BeforeAll and AfterAll methods in Nested test classes.
If you are authoring tests using the Kotlin programming language, you may also find it easier to implement BeforeAll and AfterAll methods by switching to the "per-class" test instance lifecycle mode. If a test class or test interface is not annotated with TestInstance , JUnit Jupiter will use a default lifecycle mode. To change the default test instance lifecycle mode, set the junit. Lifecycle , ignoring case.
This can be supplied as a JVM system property, as a configuration parameter in the LauncherDiscoveryRequest that is passed to the Launcher , or via the JUnit Platform configuration file see Configuration Parameters for details. For example, to set the default test instance lifecycle mode to Lifecycle. Note, however, that setting the default test instance lifecycle mode via the JUnit Platform configuration file is a more robust solution since the configuration file can be checked into a version control system along with your project and can therefore be used within IDEs and your build software.
To set the default test instance lifecycle mode to Lifecycle. Nested tests give the test writer more capabilities to express the relationship among several groups of tests.
In this example, preconditions from outer tests are used in inner tests by defining hierarchical lifecycle methods for the setup code. For example, createNewStack is a BeforeEach lifecycle method that is used in the test class in which it is defined and in all levels in the nesting tree below the class in which it is defined.
The fact that setup code from outer tests is run before inner tests are executed gives you the ability to run all tests independently. You can even run inner tests alone without running the outer tests, because the setup code from the outer tests is always executed.
In all prior JUnit versions, test constructors or methods were not allowed to have parameters at least not with the standard Runner implementations. As one of the major changes in JUnit Jupiter, both test constructors and methods are now permitted to have parameters.
This allows for greater flexibility and enables Dependency Injection for constructors and methods. ParameterResolver defines the API for test extensions that wish to dynamically resolve parameters at runtime.
If a test class constructor, a test method , or a lifecycle method see Test Classes and Methods accepts a parameter, the parameter must be resolved at runtime by a registered ParameterResolver.
TestInfoParameterResolver : if a constructor or method parameter is of type TestInfo , the TestInfoParameterResolver will supply an instance of TestInfo corresponding to the current container or test as the value for the parameter.
The TestInfo can then be used to retrieve information about the current container or test such as the display name, the test class, the test method, and associated tags. The display name is either a technical name, such as the name of the test class or test method, or a custom name configured via DisplayName. The following demonstrates how to have TestInfo injected into a test constructor, BeforeEach method, and Test method.
RepetitionInfo can then be used to retrieve information about the current repetition and the total number of repetitions for the corresponding RepeatedTest. See Repeated Test Examples. The TestReporter can be used to publish additional data about the current test run.
In addition, some IDEs print report entries to stdout or display them in the user interface for test results. While not intended to be production-ready, it demonstrates the simplicity and expressiveness of both the extension model and the parameter resolution process. MyRandomParametersTest demonstrates how to inject random values into Test methods.
For real-world use cases, check out the source code for the MockitoExtension and the SpringExtension. When the type of the parameter to inject is the only condition for your ParameterResolver , you can use the generic TypeBasedParameterResolver base class. The supportsParameters method is implemented behind the scenes and supports parameterized types.
BeforeAll and AfterAll can either be declared on static methods in a test interface or on interface default methods if the test interface or test class is annotated with TestInstance Lifecycle. Here are some examples.
ExtendWith and Tag can be declared on a test interface so that classes that implement the interface automatically inherit its tags and extensions. Another possible application of this feature is to write tests for interface contracts. For example, you can write tests for how implementations of Object. In your test class you can then implement both contract interfaces thereby inheriting the corresponding tests.
JUnit Jupiter provides the ability to repeat a test a specified number of times by annotating a method with RepeatedTest and specifying the total number of repetitions desired. Each invocation of a repeated test behaves like the execution of a regular Test method with full support for the same lifecycle callbacks and extensions. The following example demonstrates how to declare a test named repeatedTest that will be automatically repeated 10 times. In addition to specifying the number of repetitions, a custom display name can be configured for each repetition via the name attribute of the RepeatedTest annotation.
Furthermore, the display name can be a pattern composed of a combination of static text and dynamic placeholders. The following placeholders are currently supported. Thus, the display names for individual repetitions of the previous repeatedTest example would be: repetition 1 of 10 , repetition 2 of 10 , etc.
If you would like the display name of the RepeatedTest method included in the name of each repetition, you can define your own custom pattern or use the predefined RepeatedTest.
In order to retrieve information about the current repetition and the total number of repetitions programmatically, a developer can choose to have an instance of RepetitionInfo injected into a RepeatedTest , BeforeEach , or AfterEach method. The RepeatedTestsDemo class at the end of this section demonstrates several examples of repeated tests. The repeatedTest method is identical to example from the previous section; whereas, repeatedTestWithRepetitionInfo demonstrates how to have an instance of RepetitionInfo injected into a test to access the total number of repetitions for the current repeated test.
The next two methods demonstrate how to include a custom DisplayName for the RepeatedTest method in the display name of each repetition. Since the beforeEach method is annotated with BeforeEach it will get executed before each repetition of each repeated test. When using the ConsoleLauncher with the unicode theme enabled, execution of RepeatedTestsDemo results in the following output to the console.
Parameterized tests make it possible to run a test multiple times with different arguments. They are declared just like regular Test methods but use the ParameterizedTest annotation instead.
In addition, you must declare at least one source that will provide the arguments for each invocation and then consume the arguments in the test method. The following example demonstrates a parameterized test that uses the ValueSource annotation to specify a String array as the source of arguments. When executing the above parameterized test method, each invocation will be reported separately.
For instance, the ConsoleLauncher will print output similar to the following. In order to use parameterized tests you need to add a dependency on the junit-jupiter-params artifact. Please refer to Dependency Metadata for details. Parameterized test methods typically consume arguments directly from the configured source see Sources of Arguments following a one-to-one correlation between argument source index and method parameter index see examples in CsvSource.
However, a parameterized test method may also choose to aggregate arguments from the source into a single object passed to the method see Argument Aggregation. Additional arguments may also be provided by a ParameterResolver e. Specifically, a parameterized test method must declare formal parameters according to the following rules. An aggregator is any parameter of type ArgumentsAccessor or any parameter annotated with AggregateWith. Arguments that implement java.
AutoCloseable or java. Closeable which extends java. AutoCloseable will be automatically closed after AfterEach methods and AfterEachCallback extensions have been called for the current parameterized test invocation. To prevent this from happening, set the autoCloseArguments attribute in ParameterizedTest to false. Out of the box, JUnit Jupiter provides quite a few source annotations. Each of the following subsections provides a brief overview and an example for each of them.
Please refer to the Javadoc in the org. ValueSource is one of the simplest possible sources. It lets you specify a single array of literal values and can only be used for providing a single argument per parameterized test invocation. For example, the following ParameterizedTest method will be invoked three times, with the values 1 , 2 , and 3 respectively.
In order to check corner cases and verify proper behavior of our software when it is supplied bad input , it can be useful to have null and empty values supplied to our parameterized tests. The following annotations serve as sources of null and empty values for parameterized tests that accept a single argument.
NullSource : provides a single null argument to the annotated ParameterizedTest method. EmptySource : provides a single empty argument to the annotated ParameterizedTest method for parameters of the following types: java.
String , java. List , java. Set , java. Map , primitive arrays e. You can also combine NullSource , EmptySource , and ValueSource to test a wider range of null , empty , and blank input.
The following example demonstrates how to achieve this for strings. Making use of the composed NullAndEmptySource annotation simplifies the above as follows. When omitted, the declared type of the first method parameter is used. The test will fail if it does not reference an enum type. Thus, the value attribute is required in the above example because the method parameter is declared as TemporalUnit , i. Changing the method parameter type to ChronoUnit allows you to omit the explicit enum type from the annotation as follows.
The annotation provides an optional names attribute that lets you specify which constants shall be used, like in the following example.
If omitted, all constants will be used. The EnumSource annotation also provides an optional mode attribute that enables fine-grained control over which constants are passed to the test method. For example, you can exclude names from the enum constant pool or specify regular expressions as in the following examples. MethodSource allows you to refer to one or more factory methods of the test class or external classes.
Factory methods within the test class must be static unless the test class is annotated with TestInstance Lifecycle. In addition, such factory methods must not accept any arguments.
Each factory method must generate a stream of arguments , and each set of arguments within the stream will be provided as the physical arguments for individual invocations of the annotated ParameterizedTest method.
Generally speaking this translates to a Stream of Arguments i. The "arguments" within the stream can be supplied as an instance of Arguments , an array of objects e. If you only need a single parameter, you can return a Stream of instances of the parameter type as demonstrated in the following example. If you do not explicitly provide a factory method name via MethodSource , JUnit Jupiter will search for a factory method that has the same name as the current ParameterizedTest method by convention.
This is demonstrated in the following example. Streams for primitive types DoubleStream , IntStream , and LongStream are also supported as demonstrated by the following example. If a parameterized test method declares multiple parameters, you need to return a collection, stream, or array of Arguments instances or object arrays as shown below see the Javadoc for MethodSource for further details on supported return types.
In addition, Arguments. An external, static factory method can be referenced by providing its fully qualified method name as demonstrated in the following example. CsvSource allows you to express argument lists as comma-separated values i. Each string provided via the value attribute in CsvSource represents a CSV line and results in one invocation of the parameterized test. Each line within a text block represents a CSV line and results in one invocation of the parameterized test.
Using a text block, the previous example can be implemented as follows. The default delimiter is a comma , , but you can use another character by setting the delimiter attribute. Alternatively, the delimiterString attribute allows you to use a String delimiter instead of a single character.
However, both delimiter attributes cannot be set simultaneously. CsvSource uses a single quote ' as its quote character. See the 'lemon, lime' value in the example above and in the table below. An empty, quoted value '' results in an empty String unless the emptyValue attribute is set; whereas, an entirely empty value is interpreted as a null reference.
By specifying one or more nullValues , a custom value can be interpreted as a null reference see the NIL example in the table below. An ArgumentConversionException is thrown if the target type of a null reference is a primitive type. Unless it starts with a quote character, leading and trailing whitespace in a CSV column is trimmed by default. This behavior can be changed by setting the ignoreLeadingAndTrailingWhitespace attribute to true.
CsvFileSource lets you use comma-separated value CSV files from the classpath or the local file system. Each line from a CSV file results in one invocation of the parameterized test. In contrast to the syntax used in CsvSource , CsvFileSource uses a double quote " as the quote character. See the "United States of America" value in the example above. An empty, quoted value "" results in an empty String unless the emptyValue attribute is set; whereas, an entirely empty value is interpreted as a null reference.
By specifying one or more nullValues , a custom value can be interpreted as a null reference. ArgumentsSource can be used to specify a custom, reusable ArgumentsProvider. Note that an implementation of ArgumentsProvider must be declared as either a top-level class or as a static nested class.
To support use cases like CsvSource , JUnit Jupiter provides a number of built-in implicit type converters. The conversion process depends on the declared type of each method parameter. For example, if a ParameterizedTest declares a parameter of type TimeUnit and the actual type supplied by the declared source is a String , the string will be automatically converted into the corresponding TimeUnit enum constant.
In addition to implicit conversion from strings to the target types listed in the above table, JUnit Jupiter also provides a fallback mechanism for automatic conversion from a String to a given target type if the target type declares exactly one suitable factory method or a factory constructor as defined below.
The name of the method can be arbitrary and need not follow any particular convention. Note that the target type must be declared as either a top-level class or as a static nested class. For example, in the following ParameterizedTest method, the Book argument will be created by invoking the Book. Instead of relying on implicit argument conversion you may explicitly specify an ArgumentConverter to use for a certain parameter using the ConvertWith annotation like in the following example.
Note that an implementation of ArgumentConverter must be declared as either a top-level class or as a static nested class. If the converter is only meant to convert one type to another, you can extend TypedArgumentConverter to avoid boilerplate type checks. Explicit argument converters are meant to be implemented by test and extension authors. Thus, junit-jupiter-params only provides a single explicit argument converter that may also serve as a reference implementation: JavaTimeArgumentConverter.
It is used via the composed annotation JavaTimeConversionPattern. By default, each argument provided to a ParameterizedTest method corresponds to a single method parameter.
Consequently, argument sources which are expected to supply a large number of arguments can lead to large method signatures. In such cases, an ArgumentsAccessor can be used instead of multiple parameters. Using this API, you can access the provided arguments through a single argument passed to your test method.
In addition, type conversion is supported as discussed in Implicit Conversion. An instance of ArgumentsAccessor is automatically injected into any parameter of type ArgumentsAccessor. To use a custom aggregator, implement the ArgumentsAggregator interface and register it via the AggregateWith annotation on a compatible parameter in the ParameterizedTest method.
The result of the aggregation will then be provided as an argument for the corresponding parameter when the parameterized test is invoked.
Note that an implementation of ArgumentsAggregator must be declared as either a top-level class or as a static nested class. The following example demonstrates this in action with a custom CsvToPerson annotation.
By default, the display name of a parameterized test invocation contains the invocation index and the String representation of all arguments for that specific invocation. Each of them is preceded by the parameter name unless the argument is only available via an ArgumentsAccessor or ArgumentAggregator , if present in the bytecode for Java, test code must be compiled with the -parameters compiler flag.
However, you can customize invocation display names via the name attribute of the ParameterizedTest annotation like in the following example. When executing the above method using the ConsoleLauncher you will see output similar to the following. Please note that name is a MessageFormat pattern. Thus, a single quote ' needs to be represented as a doubled single quote '' in order to be displayed.
When using MethodSource or ArgumentSource , you can give names to arguments. This name will be used if the argument is included in the invocation display name, like in the example below. Each invocation of a parameterized test has the same lifecycle as a regular Test method.
For example, BeforeEach methods will be executed before each invocation. You may at will mix regular Test methods and ParameterizedTest methods within the same test class. You may use ParameterResolver extensions with ParameterizedTest methods. However, method parameters that are resolved by argument sources need to come first in the argument list.
Since a test class may contain regular tests as well as parameterized tests with different parameter lists, values from argument sources are not resolved for lifecycle methods e.
BeforeEach and test class constructors. A TestTemplate method is not a regular test case but rather a template for test cases. As such, it is designed to be invoked multiple times depending on the number of invocation contexts returned by the registered providers. Thus, it must be used in conjunction with a registered TestTemplateInvocationContextProvider extension.
Each invocation of a test template method behaves like the execution of a regular Test method with full support for the same lifecycle callbacks and extensions. Both describe methods that implement test cases.
These test cases are static in the sense that they are fully specified at compile time, and their behavior cannot be changed by anything happening at runtime. Assumptions provide a basic form of dynamic behavior but are intentionally rather limited in their expressiveness. In addition to these standard tests a completely new kind of test programming model has been introduced in JUnit Jupiter.
This new kind of test is a dynamic test which is generated at runtime by a factory method that is annotated with TestFactory. In contrast to Test methods, a TestFactory method is not itself a test case but rather a factory for test cases. Thus, a dynamic test is the product of a factory. DynamicContainer instances are composed of a display name and a list of dynamic child nodes, enabling the creation of arbitrarily nested hierarchies of dynamic nodes.
DynamicTest instances will be executed lazily, enabling dynamic and even non-deterministic generation of test cases. Any Stream returned by a TestFactory will be properly closed by calling stream. As with Test methods, TestFactory methods must not be private or static and may optionally declare parameters to be resolved by ParameterResolvers. A DynamicTest is a test case generated at runtime. It is composed of a display name and an Executable. Executable is a FunctionalInterface which means that the implementations of dynamic tests can be provided as lambda expressions or method references.
The following DynamicTestsDemo class demonstrates several examples of test factories and dynamic tests. The first method returns an invalid return type. Since an invalid return type cannot be detected at compile time, a JUnitException is thrown when it is detected at runtime. The next six methods are very simple examples that demonstrate the generation of a Collection , Iterable , Iterator , array, or Stream of DynamicTest instances. Most of these examples do not really exhibit dynamic behavior but merely demonstrate the supported return types in principle.
However, dynamicTestsFromStream and dynamicTestsFromIntStream demonstrate how easy it is to generate dynamic tests for a given set of strings or a range of input numbers. The next method is truly dynamic in nature.
Although the non-deterministic behavior of generateRandomNumberOfTests is of course in conflict with test repeatability and should thus be used with care, it serves to demonstrate the expressiveness and power of dynamic tests. For demonstration purposes, the dynamicNodeSingleTest method generates a single DynamicTest instead of a stream, and the dynamicNodeSingleContainer method generates a nested hierarchy of dynamic tests utilizing DynamicContainer.
The JUnit Platform provides TestSource , a representation of the source of a test or container used to navigate to its location by IDEs and build tools. The TestSource for a dynamic test or dynamic container can be constructed from a java. URI which can be supplied via the DynamicTest. Foo bar java. String, java. Please refer to the Javadoc for DiscoverySelectors.
The Timeout annotation allows one to declare that a test, test factory, test template, or lifecycle method should fail if its execution time exceeds a given duration. The time unit for the duration defaults to seconds but is configurable. Contrary to the assertTimeoutPreemptively assertion, the execution of the annotated method proceeds in the main thread of the test.
If the timeout is exceeded, the main thread is interrupted from another thread. This is done to ensure interoperability with frameworks such as Spring that make use of mechanisms that are sensitive to the currently running thread — for example, ThreadLocal transaction management.
To apply the same timeout to all test methods within a test class and all of its Nested classes, you can declare the Timeout annotation at the class level. It will then be applied to all test, test factory, and test template methods within that class and its Nested classes unless overridden by a Timeout annotation on a specific method or Nested class.
Please note that Timeout annotations declared at the class level are not applied to lifecycle methods. Declaring Timeout on a TestFactory method checks that the factory method returns within the specified duration but does not verify the execution time of each individual DynamicTest generated by the factory. Please use assertTimeout or assertTimeoutPreemptively for that purpose.
If Timeout is present on a TestTemplate method — for example, a RepeatedTest or ParameterizedTest — each invocation will have the given timeout applied to it. The following configuration parameters can be used to specify global timeouts for all methods of a certain category unless they or an enclosing test class is annotated with Timeout :.
More specific configuration parameters override less specific ones. For example, junit. The space between the number and the unit may be omitted.
Specifying no unit is equivalent to using seconds. When dealing with asynchronous code, it is common to write tests that poll while waiting for something to happen before performing any assertions.
In some cases you can rewrite the logic to use a CountDownLatch or another synchronization mechanism, but sometimes that is not possible — for example, if the subject under test sends a message to a channel in an external message broker and assertions cannot be performed until the message has been successfully sent through the channel. By configuring a timeout for an asynchronous test that polls, you can ensure that the test does not execute indefinitely.
This technique can be used to implement "poll until" logic very easily. When stepping through your code in a debug session, a fixed timeout limit may influence the result of the test, e. JUnit Jupiter supports the junit. The default mode is enabled. A VM runtime is considered to run in debug mode when one of its input parameters starts with -agentlib:jdwp. By default, JUnit Jupiter tests are run sequentially in a single thread. To enable parallel execution, set the junit.
Please note that enabling this property is only the first step required to execute tests in parallel. If enabled, test classes and methods will still be executed sequentially by default. Whether or not a node in the test tree is executed concurrently is controlled by its execution mode. The following two modes are available. Force execution in the same thread used by the parent. For example, when used on a test method, the test method will be executed in the same thread as any BeforeAll or AfterAll methods of the containing test class.
You can change the default by setting the junit. Alternatively, you can use the Execution annotation to change the execution mode for the annotated element and its subelements if any which allows you to activate parallel execution for individual test classes, one by one. The default execution mode is applied to all nodes of the test tree with a few notable exceptions, namely test classes that use the Lifecycle.
In the former case, test authors have to ensure that the test class is thread-safe; in the latter, concurrent execution might conflict with the configured execution order. In addition, you can configure the default execution mode for top-level classes by setting the junit. By combining both configuration parameters, you can configure classes to run in parallel but their methods in the same thread:. The opposite combination will run all methods within one class in parallel, but top-level classes will run sequentially:.
The following diagram illustrates how the execution of two top-level test classes A and B with two test methods per class behaves for all four combinations of junit. If the junit. Properties such as the desired parallelism and the maximum pool size can be configured using a ParallelExecutionConfigurationStrategy.
The JUnit Platform provides two implementations out of the box: dynamic and fixed. Alternatively, you may implement a custom strategy. To select a strategy, set the junit. Uses the mandatory junit. Allows you to specify a custom ParallelExecutionConfigurationStrategy implementation via the mandatory junit.
We can create a new test class by simply creating a public class. Its source looks as follows:. JUnit 4 requires that all test classes are public. Before we continue, I want to warn you about the problems found from this class.
This test class has three problems:. This means that if a test method fails, we have to read the source code of the test method before we know what the problem is. This is a waste of time. In other words, our test methods cannot fail. Third , our test methods write information to System.
It is OK to use System. I use this approach here because I want to demonstrate when our test methods are run and writing information to System. Additional Reading:. We just wrote our first test methods. What is software testing. To use JUnit 5 you have to make the libraries available for your test code. Jump to the section which is relevant to you, for example read the Maven part, if you are using Maven as build system.
Configure the maven-surefire-plugin and maven-failsafe-plugin to be at version 2. Once you have done this, you can start using JUnit5 in your Maven project for writing unit tests. Right-click your pom file, select Maven Update Project and select your project. This triggers an update of your project settings and dependencies. To use JUnit 5 with the Gradle build system, ensure you use at least Gradle 6. Modify your build. Your build file may contain more dependencies. If you are not using a build system and the JUnit library is not part of the classpath of your project during the creation of a new test, Eclipse prompts you to add it.
A JUnit test is a method contained in a class which is only used for testing. This is called a Test class. To mark a method as a test method, annotate it with the Test annotation. This method executes the code under test. You can use assert methods, provided by JUnit or another assert framework, to check an expected result versus the actual result. Such statement are called asserts or assert statements. Assert statements typically allow to define messages which are shown if the test fails.
You should provide here meaningful messages to make it easier for the user to identify and fix the problem. This is especially true if someone looks at the problem, who did not write the code under test or the test code. Build tools like Maven use a pattern to decide if a class is a test classes or not. The following is the list of classes Maven considers automatically during its build:.
Therefore, it is common practice to use the Test or Tests suffix at the end of test classes names. Typical, unit tests are created in a separate source folder to keep the test code separate from the real code. The standard convention from the Maven and Gradle build tools is to use:. JUnit 5 allows to use static imports for its assertStatements to make the test code short and easy to read. Static imports are a Java feature that allows fields and methods defined in a class as public static to be used without specifying the class in which the field is defined.
JUnit assert statements are typically defined as public static to allow the developer to write short test statements. The following snippet demonstrates an assert statement with and without static imports.
JUnit 5 comes with multiple assert statements, which allows you to test your code under test. Simple assert statements like the following allow to check for true, false or equality. All of them are static methods from the org. Messages can be created via lambda expressions, to avoid the overhead in case the construction of the message is expensive. Testing that certain exceptions are thrown are be done with the org.
You define the expected Exception class and provide code that should throw the exception. This lets you define which part of the test should throw the exception. The test will still fail if an exception is thrown outside of this scope. If an assert fails in a test, JUnit will stop executing the test and additional asserts are not checked.
In case you want to ensure that all asserts are checked you can assertAll. In this grouped assertion all assertions are executed, even after a failure. The error messages get also grouped together. This assert fails the method if the timeout is exceeded. If you want your tests to cancel after the timeout period is passed you can use the assertTimeoutPreemptively method.
Such a test might be flacky, in case the test server is busy, the test execution might take longer and therefore such a test might fails from time to time. The Disabled or Disabled "Why disabled" annotation marks a test to be disabled. This is useful when the underlying code has been changed and the test case has not yet been adapted of if the test demonstrates an incorrect behavior in the code which has not yet been fixed. It is best practice to provide the optional description, why the test is disabled.
Alternatively you can use Assumptions. For example, the following disables a test on Linux:. You can also write an extension for ExtendWith which defines conditions under which a test should run. JUnit 5 supports the creation of dynamic tests via code. You can also run tests with a set of different input values with parameterized tests. Dynamic test methods are annotated with TestFactory and allow to create multiple tests of type DynamicTest with your code.
They can return:. Methods annotated with BeforeEach and AfterEach are not called for dynamic tests. In the following example we define a method to return a Stream of DynamicTest instances. Junit5 also supports parameterized tests. To use them you have to add the junit-jupiter-params package as a test dependencies. The function has to be static and must return either a Collection, an Iterator, a Stream or an Array.
On execution the test method gets called once for every entry in the data source. Lets you define an array of test values. Permissible types are String , int , long , or double. Lets you pass Enum constants as test class. With the optional attribute names you can choose which constants should be used. Otherwise all attributes are used. Specifies a class that provides the test data.
The referenced class has to implement the ArgumentsProvider interface. JUnit tries to automatically convert the source strings to match the expected arguments of the test method. If you need explicit conversion you can specify a converter with the ConvertWith annotation. To define your own converter you have to implement the ArgumentConverter interface. In the following example we use the abstract SimpleArgumentConverter base class. The Nested annotation can be used to annotate inner classes which also contain tests.
This allows to group tests and have additional BeforeEach method, and one AfterEach methods. When you add nested test classes to our test class, the following rules must be followed:.
The nested test classes are annotated with Nested annotation so that the runtime can recognize the nested test classes. JUnit runs test methods is a deterministic but unpreditable order MethodSorters.
You can use the TestMethodOrder on the class to control the execution order of the tests, via:. TestMethodOrder MethodOrderer. Custom implementation - Implement your own MethodOrderer via the orderMethods method, which allows you to call context.
The TempDir annotations allows to annotate non-private fields or method parameters in a test method of type Path or File. It will also remove the temporary files are each test. At this time of writing you can use the milestone release of 5. Create a package named com. In the src folder, create the following class in the com.
Select that you want to create a new JUnit test from the list. In the following wizard ensure that the New JUnit Jupiter test flag is selected. The source folder should select the test directory. The result of the tests are displayed in the JUnit view. In our example one test should be successful and one test should show an error. This error is indicated by a red bar. The test is failing, because our multiplier class is currently not working correctly.
It does a division instead of multiplication. Fix the bug and re-run the test to get a green bar. After a few minutes you should have created a new project, a new class and a new unit test. If you feel like it, lets improve the tests a bit and write one grouped test.
The initialization of MyClass happens in every test, move the initialization to a BeforeEach method. Define a new test method which checks both condition at the same time with assertAll statement. Change the condition to make both tests fail, run the test and ensure that both are executed. The wizard should also have create the package com. Remove the generated classes from it.
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