org.junit
Annotation Type Rule


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

Annotates fields that reference rules or methods that return a rule. A field must be public, not static, and a subtype of TestRule (preferred) or MethodRule. A method must be public, not static, and must return a subtype of TestRule (preferred) or MethodRule.

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 multiple 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. You can use a RuleChain if you want to have control over the order in which the Rules are applied.

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.

Since:
4.7



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