TestWatchman/TestWatcher Rules

• 从4.9版本开始TestWatcher替代TestWatchman,它实现的是TestRule接口而不是MethodRule --http://junit.org/javadoc/latest/org/junit/rules/TestWatcher.html
• JUnit从4.7开始采用TestWatchman,它使用的是MethodRule接口，现在已经不建议使用
• TestWatcher(还有已经不建议使用的TestWatchman)是为记下测试行动规则的基类，并不需修改它。例如，这个类将保留每个通过和未通过测试的日志

TestWatcher为子类提供了四个事件方法以监控测试方法在运行过程中的状态，一般它可以作为信息记录使用。如果TestWatcher作为@ClassRule注解字段，则该测试类在运行之前（调用所有的@BeforeClass注解方法之前）会调用starting()方法；当所有@AfterClass注解方法调用结束后，succeeded()方法会被调用；若@AfterClass注解方法中出现异常，则failed()方法会被调用；最后，finished()方法会被调用；所有这些方法的Description是Runner对应的Description。如果TestWatcher作为@Rule注解字段，则在每个测试方法运行前（所有的@Before注解方法运行前）会调用starting()方法；当所有@After注解方法调用结束后，succeeded()方法会被调用；若@After注解方法中跑出异常，则failed()方法会被调用；最后，finished()方法会被调用；所有Description的实例是测试方法的Description实例。

    package com.junit.learning;
    import org.junit.After;
    import org.junit.AssumptionViolatedException;
    import org.junit.Before;
    import org.junit.Rule;
    import org.junit.Test;
    import org.junit.rules.TestRule;
    import org.junit.rules.TestWatcher;
    import org.junit.runner.Description;
    import org.junit.runners.model.Statement;

    import static org.assertj.core.api.Assertions.assertThat;

    public class WatchmanMethodTest {

        private static String watchedLog = "";

        @Rule
        public TestRule watchman = new TestWatcher() {
            @Override
            public Statement apply(Statement base, Description description) {
                return super.apply(base, description);
            }

            @Override
            protected void succeeded(Description description) {
                watchedLog += description.getDisplayName() + " " + "success!\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void failed(Throwable e, Description description) {
                watchedLog += description.getDisplayName() + " " + e.getClass().getSimpleName() + "\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void skipped(AssumptionViolatedException e, Description description) {
                watchedLog += description.getDisplayName() + " " + e.getClass().getSimpleName() + "\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void starting(Description description) {
                super.starting(description);
                System.out.println("starting");
            }

            @Override
            protected void finished(Description description) {
                super.finished(description);
                System.out.println("finished");
            }
        };

        @Before
        public void before() {
            System.out.println("before");
        }

        @After
        public void after() {
            System.out.println("after");
        }

        @Test
        public void fails() {
            System.out.println("fails");
            assertThat(1).isEqualTo(2);
        }

        @Test
        public void succeeds() {
            System.out.println("success");
        }
    }

执行结果:

    starting
    before
    success
    after
    succeeds(com.junit.learning.WatchmanTest) success!
    finished

    starting
    before
    fails
    after
    succeeds(com.junit.learning.WatchmanTest) success!
    fails(com.junit.learning.WatchmanTest) AssertionError
    finished

    package com.junit.learning;

    import org.assertj.core.api.exception.RuntimeIOException;
    import org.junit.AfterClass;
    import org.junit.AssumptionViolatedException;
    import org.junit.BeforeClass;
    import org.junit.ClassRule;
    import org.junit.Test;
    import org.junit.rules.TestRule;
    import org.junit.rules.TestWatcher;
    import org.junit.runner.Description;
    import org.junit.runners.model.Statement;

    import static org.assertj.core.api.Assertions.assertThat;

    public class WatchmanClassTest {

        private static String watchedLog ="";

        @ClassRule
        public static TestRule watchman = new TestWatcher() {
            @Override
            public Statement apply(Statement base, Description description) {
                return super.apply(base, description);
            }

            @Override
            protected void succeeded(Description description) {
                watchedLog += description.getDisplayName() + " " + "success!\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void failed(Throwable e, Description description) {
                watchedLog += description.getDisplayName() + " " + e.getClass().getSimpleName() + "\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void skipped(AssumptionViolatedException e, Description description) {
                watchedLog += description.getDisplayName() + " " + e.getClass().getSimpleName() + "\n";
                System.out.println(watchedLog);
            }

            @Override
            protected void starting(Description description) {
                super.starting(description);
                System.out.println("starting");
            }

            @Override
            protected void finished(Description description) {
                super.finished(description);
                System.out.println("finished");
            }
        };

        @BeforeClass
        public static void before(){
            System.out.println("before");
        }

        @AfterClass
        public static void after(){
            System.out.println("after");
            throw new RuntimeIOException("");
        }

        @Test
        public void fails() {
            System.out.println("fails");
            assertThat(1).isEqualTo(2);
        }

        @Test
        public void succeeds() {
            System.out.println("success");
        }
    }

运行结果如下:

    success
    fails
    starting
    before
    after
    com.junit.learning.WatchmanClassTest RuntimeIOException
    finished