# JUnit 测试监听器– JUnit `RunListener`示例 > 原文： [https://howtodoinjava.com/junit/how-to-add-listner-in-junit-testcases/](https://howtodoinjava.com/junit/how-to-add-listner-in-junit-testcases/) 监听器通常可以帮助监听我们感兴趣的事件。 这可能有几个原因。 例如，我们添加了监听器以添加特定的日志，在 Java GUI 编程中处理 UI 事件等。 JUnit 还支持通过`RunListener`类执行测试时添加监听器。 该监听器可用于从改进日志记录到测试特定逻辑的各种目的。 ## 1\. JUnit `RunListener`示例 #### 1.1 JUnit 测试类 我们仅在下面举例说明两个测试类。 我们将监视为这些类编写的测试而打印的日志。 ```java package com.howtodoinjava.junit; import junit.framework.Assert; import org.junit.Test; public class TestFeatureOne { @Test public void testFirstFeature() { Assert.assertTrue(true); } } ``` ```java package com.howtodoinjava.junit; import junit.framework.Assert; import org.junit.Ignore; import org.junit.Test; public class TestFeatureTwo { @Test public void testSecondFeature() { Assert.assertTrue(true); } @Test @Ignore public void testSecondFeatureIngored() { Assert.assertTrue(true); } } ``` #### 1.2 JUnit 测试监听器 让我们编写运行监听器。 该监听器将扩展 JUnit 提供的`RunListener`类。 > 我们可以完全不包含任何方法来覆盖任何数量的方法`RunListener`类。 ```java package com.howtodoinjava.junit.suite; import org.junit.runner.Description; import org.junit.runner.Result; import org.junit.runner.notification.Failure; import org.junit.runner.notification.RunListener; public class ExecutionListener extends RunListener { /** * Called before any tests have been run. * */ public void testRunStarted(Description description) throws java.lang.Exception { System.out.println("Number of tests to execute : " + description.testCount()); } /** * Called when all tests have finished * */ public void testRunFinished(Result result) throws java.lang.Exception { System.out.println("Number of tests executed : " + result.getRunCount()); } /** * Called when an atomic test is about to be started. * */ public void testStarted(Description description) throws java.lang.Exception { System.out.println("Starting execution of test case : "+ description.getMethodName()); } /** * Called when an atomic test has finished, whether the test succeeds or fails. * */ public void testFinished(Description description) throws java.lang.Exception { System.out.println("Finished execution of test case : "+ description.getMethodName()); } /** * Called when an atomic test fails. * */ public void testFailure(Failure failure) throws java.lang.Exception { System.out.println("Execution of test case failed : "+ failure.getMessage()); } /** * Called when a test will not be run, generally because a test method is annotated with Ignore. * */ public void testIgnored(Description description) throws java.lang.Exception { System.out.println("Execution of test case ignored : "+ description.getMethodName()); } } ``` ## 2\. JUnit 监听器执行 现在，让我们运行测试并观察监听器的输出。 ```java package com.howtodoinjava.junit.suite; import org.junit.runner.JUnitCore; import com.howtodoinjava.junit.TestFeatureOne; import com.howtodoinjava.junit.TestFeatureTwo; public class ExecuteWithRunListener { public static void main(String[] args) { JUnitCore runner = new JUnitCore(); <strong>//Adding listener here</strong> runner.addListener(new ExecutionListener()); runner.run(TestFeatureOne.class, TestFeatureTwo.class); } } ``` 程序输出。 ```java Number of tests to execute : 3 Starting execution of test case : testFirstFeature Finished execution of test case : testFirstFeature Starting execution of test case : testSecondFeature Finished execution of test case : testSecondFeature Execution of test case ignored : testSecondFeatureIngored Number of tests executed : 2 ``` 显然，添加监听器可通过改进的日志记录支持对测试执行提供额外的控制。 学习愉快！