1 package org.junit.rules; 2 3 import org.junit.Rule; 4 import org.junit.runners.model.FrameworkMethod; 5 import org.junit.runners.model.Statement; 6 7 /** 8 * A MethodRule is an alteration in how a test method is run and reported. 9 * Multiple {@link MethodRule}s can be applied to a test method. The 10 * {@link Statement} that executes the method is passed to each annotated 11 * {@link Rule} in turn, and each may return a substitute or modified 12 * {@link Statement}, which is passed to the next {@link Rule}, if any. For 13 * examples of how this can be useful, see these provided MethodRules, 14 * or write your own: 15 * 16 * <ul> 17 * <li>{@link ErrorCollector}: collect multiple errors in one test method</li> 18 * <li>{@link ExpectedException}: make flexible assertions about thrown exceptions</li> 19 * <li>{@link ExternalResource}: start and stop a server, for example</li> 20 * <li>{@link TemporaryFolder}: create fresh files, and delete after test</li> 21 * <li>{@link TestName}: remember the test name for use during the method</li> 22 * <li>{@link TestWatchman}: add logic at events during method execution</li> 23 * <li>{@link Timeout}: cause test to fail after a set time</li> 24 * <li>{@link Verifier}: fail test if object state ends up incorrect</li> 25 * </ul> 26 * 27 * Note that {@link MethodRule} has been replaced by {@link TestRule}, 28 * which has the added benefit of supporting class rules. 29 * 30 * @since 4.7 31 */ 32 public interface MethodRule { 33 /** 34 * Modifies the method-running {@link Statement} to implement an additional 35 * test-running rule. 36 * 37 * @param base The {@link Statement} to be modified 38 * @param method The method to be run 39 * @param target The object on which the method will be run. 40 * @return a new statement, which may be the same as {@code base}, 41 * a wrapper around {@code base}, or a completely new Statement. 42 */ apply(Statement base, FrameworkMethod method, Object target)43 Statement apply(Statement base, FrameworkMethod method, Object target); 44 } 45