使用一个活动来测试Espresso中的所有案例

Question

我想使用Espresso使用IdlingResource来测试我的Android项目，根据ActivityTestRule，默认情况下每个Test方法应该启动一次Activity。但是，我想使用相同的活动测试案例。我尝试将launchActivity设置为false，但结果是NullPointerException。

@LargeTest
@RunWith(AndroidJUnit4.class)
public class VideoViewPlayingTest {

    @Rule
    public MainActivityTestRule mRule = new MainActivityTestRule(MainActivity.class, true, false);


    private BaseIdleResource mResource;

    @Before
    public void setUp() {
        mResource = new BaseIdleResource(mRule.getActivity());
        Espresso.registerIdlingResources(mResource);
    }

    @After
    public void tearDown() {
        Espresso.unregisterIdlingResources(mResource);
    }



    @Test
    public void controllerViewKeepShowing() {
        onView(withId(R.id.videoView)).perform(click());
        ViewInteraction linearLayout = onView(
                withId(R.id.controller_view));
        linearLayout.check(matches(isCompletelyDisplayed()));
    }


    @Test
    public void playButtonShowWhenControllerViewShow() {
        onView(withId(R.id.videoView)).perform(click());
        ViewInteraction pauseButton = onView(
                withId(R.id.pause));
        pauseButton.check(matches(isCompletelyDisplayed()));
    }
}

错误讯息：

    java.lang.NullPointerException
    at android.support.test.espresso.core.deps.guava.base.Preconditions.checkNotNull(Preconditions.java:210)
    at android.support.test.espresso.core.deps.guava.collect.SingletonImmutableList.<init>(SingletonImmutableList.java:40)
    at android.support.test.espresso.core.deps.guava.collect.ImmutableList.copyOf(ImmutableList.java:293)
    at android.support.test.espresso.Espresso.unregisterIdlingResources(Espresso.java:127)
    at com.hustunique.sample.VideoViewPlayingTest.tearDown(VideoViewPlayingTest.java:61)
    at java.lang.reflect.Method.invoke(Native Method)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:33)
    at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55)
    at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:270)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runners.Suite.runChild(Suite.java:128)
    at org.junit.runners.Suite.runChild(Suite.java:27)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
    at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
    at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
    at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1985)

我该如何解决这个问题？