如何等到吐司完成？仅在 toast 隐藏 prev 测试后才开始第二次测试

Question

这里是我的 Espresso 测试：

@RunWith(AndroidJUnit4::class)
class AddTraderActivityNetworkTest {
    private val context = InstrumentationRegistry.getInstrumentation().getContext()
    private lateinit var mockServer: MockWebServer

    @Rule
    @JvmField
    var addTraderIntentTestRule: IntentsTestRule<AddTraderActivity> = IntentsTestRule(AddTraderActivity::class.java)

    @Before
    fun setup() {
        mockServer = MockWebServer()
        mockServer.start(8081)
    }

    @Test
    fun buttonStart_click_clientError_showToast() {
        mockServer.enqueue(MockResponse()
                .setResponseCode(400))

        onView(withId(R.id.baseTextInputEditText))
                .perform(typeText(BASE_TEST))
        onView(withId(R.id.quoteTextInputEditText))
                .perform(typeText(QUOTE_TEST))
        onView(withId(R.id.startButton))
                .perform(click())
        onView(withText(R.string.client_error)).inRoot(ToastMatcher())
                .check(matches(isDisplayed()))
    }

    @Test
    fun buttonStart_click_clientError_traderNotFound_showToast() {
        mockServer.enqueue(MockResponse()
                .setResponseCode(404)
                .setBody(FileUtil.getStringFromFile(context, "trader_404_not_add.json")))

        onView(withId(R.id.baseTextInputEditText))
                .perform(typeText(BASE_TEST))
        onView(withId(R.id.quoteTextInputEditText))
                .perform(typeText(QUOTE_TEST))
        onView(withId(R.id.startButton))
                .perform(click())
        onView(withText(R.string.trader_not_added)).inRoot(ToastMatcher())
                .check(matches(isDisplayed()))
    }

当统计所有这些测试时，其中一个肯定会失败并显示消息：

androidx.test.espresso.NoMatchingViewException: No views in hierarchy found matching: with string from resource id: <2131623975>[client_error] value: Client Error

View Hierarchy:
+>LinearLayout{id=-1, visibility=VISIBLE, width=566, height=149, has-focus=false, has-focusable=false, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, layout-params=WM.LayoutParams{(0,192)(wrapxwrap) gr=#51 ty=2005 fl=#1000098 fmt=-3 wanim=0x1030004}, tag=null, root-is-layout-requested=false, has-input-connection=false, x=0.0, y=0.0, child-count=1}
|
+->AppCompatTextView{id=16908299, res-name=message, visibility=VISIBLE, width=416, height=83, has-focus=false, has-focusable=false, has-window-focus=false, is-clickable=false, is-enabled=true, is-focused=false, is-focusable=false, is-layout-requested=false, is-selected=false, layout-params=android.widget.LinearLayout$LayoutParams@b08322e, tag=null, root-is-layout-requested=false, has-input-connection=false, x=75.0, y=33.0, text=Trader not added, input-type=0, ime-target=false, has-links=false}
|
at dalvik.system.VMStack.getThreadStackTrace(Native Method)
at java.lang.Thread.getStackTrace(Thread.java:580)
at androidx.test.espresso.base.DefaultFailureHandler.getUserFriendlyError(DefaultFailureHandler.java:96)
at androidx.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:59)
at androidx.test.espresso.ViewInteraction.waitForAndHandleInteractionResults(ViewInteraction.java:316)
at androidx.test.espresso.ViewInteraction.check(ViewInteraction.java:300)
at com.myproject.activity.AddTraderActivityNetworkTest.buttonStart_click_clientError_showToast(AddTraderActivityNetworkTest.kt:64)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at androidx.test.internal.runner.junit4.statement.RunBefores.evaluate(RunBefores.java:80)
at androidx.test.internal.runner.junit4.statement.RunAfters.evaluate(RunAfters.java:61)
at androidx.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:531)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)

发生这种情况是因为新测试已开始，但之前测试的 toast 仍未隐藏。结果，我收到错误消息，找不到带有消息的吐司：

androidx.test.espresso.NoMatchingViewException: No views in hierarchy found matching: with string from resource id: <2131623975>[client_error] value: Client Error

问题是： 我怎么能等到 toast 被隐藏并且只有在开始第二次测试之后？

Answer 1

这是一个 java 中的函数，用于在 x 毫秒内显示 Toast

private Toast myToast;

private void showToast(int ms) {

    myToast = Toast.makeText(this, "Your message", Toast.LENGTH_LONG);

    new Handler().postDelayed(new Runnable() {

        @Override
        public void run() {
            myToast.cancel(); // do this to be sure Toast is gone
            // here you can start your new test or set a flag to say Toast is finish
        }
    }, ms);
}