org.junit.Rule Maven / Gradle / Ivy
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package org.junit;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Annotates fields that reference rules or methods that return a rule. A field must be public, not
* static, and a subtype of {@link org.junit.rules.TestRule} (preferred) or
* {@link org.junit.rules.MethodRule}. A method must be public, not static,
* and must return a subtype of {@link org.junit.rules.TestRule} (preferred) or
* {@link org.junit.rules.MethodRule}.
*
* The {@link org.junit.runners.model.Statement} passed
* to the {@link org.junit.rules.TestRule} will run any {@link Before} methods,
* then the {@link Test} method, and finally any {@link After} methods,
* throwing an exception if any of these fail. If there are multiple
* annotated {@link Rule}s 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 {@link org.junit.rules.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
* {@link org.junit.rules.TestRule}.
*
* @since 4.7
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface Rule {
}