1package org.junit;
2
3import java.lang.annotation.ElementType;
4import java.lang.annotation.Retention;
5import java.lang.annotation.RetentionPolicy;
6import java.lang.annotation.Target;
7
8/**
9 * Annotates static fields that contain rules. Such a field must be public,
10 * static, and a subtype of {@link org.junit.rules.TestRule}.
11 * The {@link org.junit.runners.model.Statement} passed
12 * to the {@link org.junit.rules.TestRule} will run any {@link BeforeClass} methods,
13 * then the entire body of the test class (all contained methods, if it is
14 * a standard JUnit test class, or all contained classes, if it is a
15 * {@link org.junit.runners.Suite}), and finally any {@link AfterClass} methods.
16 *
17 * The statement passed to the {@link org.junit.rules.TestRule} will never throw an exception,
18 * and throwing an exception from the {@link org.junit.rules.TestRule} will result in undefined
19 * behavior.  This means that some {@link org.junit.rules.TestRule}s, such as
20 * {@link org.junit.rules.ErrorCollector},
21 * {@link org.junit.rules.ExpectedException},
22 * and {@link org.junit.rules.Timeout},
23 * have undefined behavior when used as {@link ClassRule}s.
24 *
25 * If there are multiple
26 * annotated {@link ClassRule}s on a class, they will be applied in an order
27 * that depends on your JVM's implementation of the reflection API, which is
28 * undefined, in general.
29 *
30 * For example, here is a test suite that connects to a server once before
31 * all the test classes run, and disconnects after they are finished:
32 *
33 * <pre>
34 *
35 * &#064;RunWith(Suite.class)
36 * &#064;SuiteClasses({A.class, B.class, C.class})
37 * public class UsesExternalResource {
38 * 	public static Server myServer= new Server();
39 *
40 * 	&#064;ClassRule
41 * 	public static ExternalResource resource= new ExternalResource() {
42 * 		&#064;Override
43 * 		protected void before() throws Throwable {
44 * 			myServer.connect();
45 * 		};
46 *
47 * 		&#064;Override
48 * 		protected void after() {
49 * 			myServer.disconnect();
50 * 		};
51 * 	};
52 * }
53 * </pre>
54 *
55 * For more information and more examples, see {@link org.junit.rules.TestRule}.
56 */
57@Retention(RetentionPolicy.RUNTIME)
58@Target({ElementType.FIELD})
59public @interface ClassRule {
60}
61