From a given set of test classes, the Categories runner runs only the classes and methods that are annotated with either the category given with the @IncludeCategory annotation, or a subtype of that category. Either classes or interfaces can be used as categories. Subtyping works, so if you say @IncludeCategory(SuperClass.class), a test marked @Category({SubClass.class}) will be run.

You can also exclude categories by using the @ExcludeCategory annotation

Example:

public interface FastTests { /* category marker */ } public interface SlowTests { /* category marker */ } public class A { @Test public void a() { fail(); } @Category(SlowTests.class) @Test public void b() { } } @Category({SlowTests.class, FastTests.class}) public class B { @Test public void c() { } } @RunWith(Categories.class) @IncludeCategory(SlowTests.class) @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite public class SlowTestSuite { // Will run A.b and B.c, but not A.a } @RunWith(Categories.class) @IncludeCategory(SlowTests.class) @ExcludeCategory(FastTests.class) @SuiteClasses( { A.class, B.class }) // Note that Categories is a kind of Suite public class SlowTestSuite { // Will run A.b, but not A.a or B.c }

You can use categories with either maven-surefire-plugin (for unit tests) or maven-failsafe-plugin (for integration tests). Using either plugin, you can configure a list of categories to include or exclude. Without using either option, all tests will be executed by default.

<build> <plugins> <plugin> <artifactId>maven-surefire-plugin</artifactId> <configuration> <groups>com.example.FastTests,com.example.RegressionTests</groups> </configuration> </plugin> </plugins> </build>

Similarly, to exclude a certain list of categories, you would use the <excludedGroups/> configuration element.

Gradle's test task allows the specification of the JUnit categories you want to include and exclude.

test { useJUnit { includeCategories 'org.gradle.junit.CategoryA' excludeCategories 'org.gradle.junit.CategoryB' } } 

SBT's junit-interface allows the specification of JUnit categories via --include-categories=<CLASSES> and --exclude-categories=<CLASSES>.

Categories are used to add metadata on the tests.

The frequently encountered categories usages are about:

• The type of automated tests: UnitTests, IntegrationTests, SmokeTests, RegressionTests, PerformanceTests ...
• How quick the tests execute: SlowTests, QuickTests
• In which part of the ci build the tests should be executed: NightlyBuildTests
• The state of the test: UnstableTests, InProgressTests

This is also used to add project specific metadata like which feature of a project is covered by the test.

See usages of Junit Categories on github hosted projects