我的方法是创建自己的ActivityTestRule,所以我只是从这个类中复制了整个代码,并将其命名为MyActivityTestRule.

在仪器测试的情况下,规则还需要有关我们如何开始活动的信息.我更愿意自己推出它而不是为我做环境.例如：

@Rule
    public MyActivityTestRule<ActivityToStartWith> activityRule = new MyActivityTestRule<>(
           ActivityToStartWith.class,true,false
    );

所以我也在@Before注释方法中启动我的活动：

@Before
    public void setUp() throws Exception {
        activityRule.launchActivity(new Intent());
    }

并在@After注释方法中进行清理：

@After
    public void tearDown() throws Exception {
        cleanUpDataBaseAfterTest();
        returnToStartingActivity(activityRule);
    }

这些方法 – setUp(),tearDown()是每次测试运行之前/之后调用的必要条件 – 以确保测试开始期间的应用程序状态是正确的.

在MyActivityTestRule中,到目前为止我做了一些修改.首先是应用方法的变更来自：

@Override
    public Statement apply(final Statement base,Description description) {
       return new ActivityStatement(super.apply(base,description));
    }

这对我来说是个未知的事情,因为放在ActivityTestRule中的ActivityStatement具有super.apply方法,所以它还在UiThreadStatement中包装了测试语句：

public class UiThreadStatement extends Statement {
    private final Statement mBase;
    private final boolean mRunOnUiThread;

    public UiThreadStatement(Statement base,boolean runOnUiThread) {
        mBase = base;
        mRunOnUiThread = runOnUiThread;
    }

    @Override
    public void evaluate() throws Throwable {
        if (mRunOnUiThread) {
            final AtomicReference<Throwable> exceptionRef = new AtomicReference<>();
            getInstrumentation().runOnMainSync(new Runnable() {
                public void run() {
                    try {
                        mBase.evaluate();
                    } catch (Throwable throwable) {
                        exceptionRef.set(throwable);
                    }
                }
            });
            Throwable throwable = exceptionRef.get();
            if (throwable != null) {
                throw throwable;
            }
        } else {
            mBase.evaluate();
        }
    }
}

不管我对我的测试做什么我永远不能创建case mRunOnUiThread布尔值为true.如果在我的测试用例中,将出现带有注释@UiThreadTest的测试 – 或者这就是我从代码中理解的内容.它永远不会发生,我不使用任何类似的东西所以我决定忽略这个UiThreadStatement并将MyActivityTestRule更改为：

@Override
    public Statement apply(final Statement base,Description description) {
       return new ActivityStatement(base);
    }

我的测试用例没有任何问题.感谢我留下的所有东西 – 包围mBase.evaluate()的是：

private class ActivityStatement extends Statement {

    private final Statement mBase;

    public ActivityStatement(Statement base) {
        mBase = base;
    }

    @Override
    public void evaluate() throws Throwable {
        try {
            if (mLaunchActivity) {
                mActivity = launchActivity(getActivityIntent());
            }
            mBase.evaluate();
        } finally {
            finishActivity();
            afterActivityFinished();
        }
    }
}

通常,只有在ActivityTestRule的第3个参数中设置构造函数值true时才会调用launchActivity.但我自己在setUp()中启动测试,所以它永远不会发生.

根据我的理解,mBase.evaluate()在@Test注释方法中运行我的代码.它还会在throwable被抛出期间停止测试用例.这意味着我可以抓住它并重新启动它 – 就像在那里提出的那样：
How to Re-run failed JUnit tests immediately?

好吧,我做了类似的事情：

public class ActivityRetryStatement extends Statement {

        private final Statement mBase;
        private final int MAX_RUNS = 2;

        public ActivityRetryStatement(Statement base) {
            mBase = base;
        }

        @Override
        public void evaluate() throws Throwable {

            Throwable throwable = null;

            for (int i = 0; i < MAX_RUNS; i++) {

                try {
                    mBase.evaluate();
                    // if you reach this lane that means evaluate passed
                    // and you don't need to do the next run
                    break;
                } catch (Throwable t) {

                    // save first throwable if occurred
                    if (throwable == null) {
                        throwable = t;
                    }

                    // my try that didn't work
                    launchActivity(testInitialIntent);
                    // I've returned test to starting screen but
                    // mBase.envaluate() didn't make it run again

                    // it would be cool now to:
                    // - invoke @After
                    // - finish current activity
                    // - invoke @Before again and start activity
                    // - mBase.evaluate() should restart @Test on activity started again by @Before
                } 
            }

            finishActivity();
            afterActivityFinished();

            // if 1st try fail but 2nd passes inform me still that there was error
            if (throwable != null) {
                throw throwable;
            }
        }
    }

因此,catch块中的那些注释是我不知道该怎么做的部分.我尝试在setUp()中使用的intent上执行launchActivity,以便第一次运行测试.但是mBase.evaluate()并没有让它做出反应(测试用例没有再次发生) – 没有发生任何事情它不会真的拯救我,我认为.我在@SetUp中缺少一些启动,它没有被再次调用.我真的想找到一种方法如何正确地重新启动整个测试生命周期@Before @Test @After再次.也许有人从代码中调用Instrumentation或TestRunner.

有关如何做到的任何想法？