Android：Espresso：按下返回按钮-NoActivityResumedException

Question

Android Studio 3.2

我要测试按返回按钮。 因此，这里是我的意式浓缩咖啡的测试：

base

但是测试失败：

@RunWith(AndroidJUnit4::class)
class AddTraderActivityTest {
    @get:Rule
    var addTraderActivity: IntentsTestRule<AddTraderActivity> = IntentsTestRule(AddTraderActivity::class.java)
 @Test
    fun backButton_press() {
        try {
            pressBack()
            fail("Should have thrown NoActivityResumedException")
        } catch (expected: NoActivityResumedException) 
        {}
    }