Package org.junit

Annotation Type Rule

@Retention(RUNTIME)
@Target({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 methods first, then fields. 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 after Rules defined by methods, i.e. the Statements returned by the former will be executed around those returned by the latter.

Usage

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.

Ordering

You can use order() if you want to have control over the order in which the Rules are applied.

 public class ThreeRules {
     @Rule(order = 0)
     public LoggingRule outer = new LoggingRule("outer rule");

     @Rule(order = 1)
     public LoggingRule middle = new LoggingRule("middle rule");

     @Rule(order = 2)
     public LoggingRule inner = new LoggingRule("inner rule");

     // ...
 }
 

Since:

4.7

Field Summary

Fields

Modifier and Type	Fields	Description
static int	DEFAULT_ORDER

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
int	order	Specifies the order in which rules are applied.

Field Detail

DEFAULT_ORDER

static final int DEFAULT_ORDER

Element Detail

order

int order

Specifies the order in which rules are applied. The rules with a higher value are inner.

Since:

4.13

Default:

-1