org.junit

Annotation Type Rule

@Retention(value=RUNTIME)
@Target(value={FIELD,METHOD})
public @interface Rule

Annotates fields that contain rules or methods that return a rule. A field must be public, not static, and a subtype of TestRule. A method must be public, not static and must return a subtype of TestRule. The Statement passed to the TestRule will run any Before methods, then the Test method, and finally any After methods, throwing an exception if any of these fail. If there are multiple annotated Rules on a class, they will be applied in order of fields first, then methods. However, if there are mutliple fields (or methods) they will be applied in an order that depends on your JVM's implementation of the reflection API, which is undefined, in general. Rules defined by fields will always be applied before Rules defined by methods. For example, here is a test class that creates a temporary folder before each test method, and deletes it after each:

 public static class HasTempFolder {
        @Rule
        public TemporaryFolder folder= new TemporaryFolder();

        @Test
        public void testUsingTempFolder() throws IOException {
                File createdFile= folder.newFile("myfile.txt");
                File createdFolder= folder.newFolder("subfolder");
                // ...
     }
 }
 

And the same using a method.

 public static class HasTempFolder {
  private TemporaryFolder folder= new TemporaryFolder();

  @Rule
  public TemporaryFolder getFolder() {
      return folder;
     }

  @Test
  public void testUsingTempFolder() throws IOException {
      File createdFile= folder.newFile("myfile.txt");
      File createdFolder= folder.newFolder("subfolder");
      // ...
     }
 }
 

For more information and more examples, see TestRule. Note: for backwards compatibility, this annotation may also mark fields or methods of type MethodRule, which will be honored. However, this is a deprecated interface and feature.

Since:

4.7