Junit TestRule

作者：範宗雲来源：原创发布时间：2015-04-13 归档：junit

环境： JDK 7 Maven 3 Junit 4.11 Eclipse Luna

TestRule

		    import org.junit.rules.TestRule;
			import org.junit.runner.Description;
			import org.junit.runners.model.Statement;
			
			public class LoggerRule implements TestRule {
			
				@Override
				public Statement apply(final Statement base, final Description description) {
					return new Statement() {
						@Override
						public void evaluate() throws Throwable {
							String method = description.getMethodName();
							Logger.debug("---> " + method + " run before");
							base.evaluate();
							Logger.debug("---> " + method + " run after");
						}
					};
				}
			
			}

@Rule

		    import org.junit.Rule;
			import org.junit.Test;
			import org.junit.rules.TestRule;
			
			public class RuleUsageTest {
			
				@Rule
				public TestRule loggerRule = new LoggerRule();
				
				@Test
				public void testMethod() {
					System.out.println("---> testMethod is running");
				}
				
			}

TestRule 类似于拦截器的作用, 它允许你在测试用例执行前后添加一些额外的操作。@Rule 要求必须为 public 修饰符修饰, 且不能是静态以及类型必须为 TestRule 类型。RuleUsageTest --> Run As JUnit Test 执行结果：

---> testMethod run before
---> testMethod is running
---> testMethod run after

看起来用 @Before, @After, @BeforeClass, @AfterClass 也可以实现同样的效果。但如果测试有多处需要用到同样的逻辑, 使用 TestRule 可以避免重复编写同样的逻辑代码。

@ClassRule

		    public class ATest {
			
				@Test
				public void testAMethod() {
					System.out.println("---> testAMethod is running");
				}
				
			}

		    public class BTest {
			
				@Test
				public void testBMethod() {
					System.out.println("---> testBMethod is running");
				}
				
			}

		    @RunWith(Suite.class)
			@SuiteClasses({ATest.class, BTest.class})
			public class CTestSuite {
			
				@ClassRule
				public static TestRule rule = new TestRule() {
					@Override
					public Statement apply(final Statement base, Description description) {
						return new Statement() {
							@Override
							public void evaluate() throws Throwable {
								Logger.debug("---> run junit test before");
								base.evaluate();
								Logger.debug("---> run junit test after");
							}
						};
					}
				};
				
			}

@ClassRule 要求必须为 public static TestRule 修饰。CTestSuite --> Run As JUnit Test 执行结果：

---> run junit test before
---> testAMethod is running
---> testBMethod is running
---> run junit test after

RuleChain

		    import org.junit.Rule;
			import org.junit.Test;
			import org.junit.rules.RuleChain;
			import org.junit.rules.TestRule;
			import org.junit.runner.Description;
			import org.junit.runners.model.Statement;
			
			public class RuleChainUsageTest {
			
				@Rule
				public TestRule chain = RuleChain.outerRule(new LoggerRule()).around(
					new TestRule() {
						@Override
						public Statement apply(final Statement base, Description description) {
							return new Statement() {
								@Override
								public void evaluate() throws Throwable {
									System.out.println("------------------------------");
									base.evaluate();
									System.out.println("------------------------------");
								}
							};
						}
					}
				);
				
				@Test
				public void testMethod() {
					System.out.println("---> testMethod is running");
				}
				
			}

RuleChainUsageTest --> Run As JUnit Test 执行结果：

---> testMethod run before
------------------------------
---> testMethod is running
------------------------------
---> testMethod run after

示例代码下载

junit-rule.zip