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 fields that reference rules or methods that return a rule. A field must be public, not
10 * static, and a subtype of {@link org.junit.rules.TestRule} (preferred) or
11 * {@link org.junit.rules.MethodRule}. A method must be public, not static,
12 * and must return a subtype of {@link org.junit.rules.TestRule} (preferred) or
13 * {@link org.junit.rules.MethodRule}.
14 * <p>
15 * The {@link org.junit.runners.model.Statement} passed
16 * to the {@link org.junit.rules.TestRule} will run any {@link Before} methods,
17 * then the {@link Test} method, and finally any {@link After} methods,
18 * throwing an exception if any of these fail.  If there are multiple
19 * annotated {@link Rule}s on a class, they will be applied in order of fields first, then methods.
20 * However, if there are multiple fields (or methods) they will be applied in an order
21 * that depends on your JVM's implementation of the reflection API, which is
22 * undefined, in general. Rules defined by fields will always be applied
23 * before Rules defined by methods. You can use a {@link org.junit.rules.RuleChain} if you want
24 * to have control over the order in which the Rules are applied.
25 * <p>
26 * For example, here is a test class that creates a temporary folder before
27 * each test method, and deletes it after each:
28 * <pre>
29 * public static class HasTempFolder {
30 *     &#064;Rule
31 *     public TemporaryFolder folder= new TemporaryFolder();
32 *
33 *     &#064;Test
34 *     public void testUsingTempFolder() throws IOException {
35 *         File createdFile= folder.newFile(&quot;myfile.txt&quot;);
36 *         File createdFolder= folder.newFolder(&quot;subfolder&quot;);
37 *         // ...
38 *     }
39 * }
40 * </pre>
41 * <p>
42 * And the same using a method.
43 * <pre>
44 * public static class HasTempFolder {
45 *     private TemporaryFolder folder= new TemporaryFolder();
46 *
47 *     &#064;Rule
48 *     public TemporaryFolder getFolder() {
49 *         return folder;
50 *     }
51 *
52 *     &#064;Test
53 *     public void testUsingTempFolder() throws IOException {
54 *         File createdFile= folder.newFile(&quot;myfile.txt&quot;);
55 *         File createdFolder= folder.newFolder(&quot;subfolder&quot;);
56 *         // ...
57 *     }
58 * }
59 * </pre>
60 * <p>
61 * For more information and more examples, see
62 * {@link org.junit.rules.TestRule}.
63 *
64 * @since 4.7
65 */
66@Retention(RetentionPolicy.RUNTIME)
67@Target({ElementType.FIELD, ElementType.METHOD})
68public @interface Rule {
69
70}