Espresso - Custom find view got uncaught NoMatchingViewException - without IdlingResource

Question

Here, I want a custom find view function: if with a given Matcher can NOT found the view in 10 seconds, return a boolean false, otherwise return the view. Note, I dont want use IdlingResource. My code is as below:

AiFinder.java

package BaseOpration;
import android.support.test.espresso.NoMatchingViewException;
import android.support.test.espresso.ViewAssertion;
import android.support.test.espresso.ViewInteraction;
import android.view.View;

import org.hamcrest.Matcher;
import static android.support.test.espresso.Espresso.onView;

/**
 * Created by Real on 2018/3/14.
 */

public class AiFinder {

    public static Object findElement(Matcher<View> matcher){
        int times = 0;
        while(times < Configer.timeOut){
            try{
                return onView(matcher);
            }
            catch (NoMatchingViewException ex){
                try {
                    System.out.printf("Retrying...");
                    Thread.sleep(1000);
                } catch (Exception e) {
//                    e.printStackTrace();
                    System.out.printf("111");
                }
                times += 1;
            }
        }
        return false;
    }

    public static void checkMatch(Object element, ViewAssertion assertion){
        if(element instanceof Boolean){
            try {
                throw new Exception("Can not find the view");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        else{
            ViewInteraction e = (ViewInteraction) element;
            e.check(assertion);
        }
    }
}

and my test code:

    @Test
    public void testLogin() throws Exception{
        onView(withId(R.id.tv_main_username)).perform(click());
        onView(withId(R.id.et_username)).perform(clearText(), replaceText("xxx"), closeSoftKeyboard());
        onView(withId(R.id.et_password)).perform(clearText(), replaceText("xxxx"), closeSoftKeyboard());
        onView(withId(R.id.bt_user_login)).perform(click());
        Object userName = AiFinder.findElement(withId(R.id.tv_main_username));
        AiFinder.checkMatch(userName, matches(withText("Hello")));
    }

Actually, I see it enters the username and password and after click the login button it gives the output:

$ adb shell am instrument -w -r   -e debug false -e class **.**.AutomationEspressoTest#testLogin **.**.test/android.support.test.runner.AndroidJUnitRunner
Client not ready yet..
Started running tests

android.support.test.espresso.NoMatchingViewException: No views in hierarchy found matching: with id: **.**:id/tv_main_username

View Hierarchy:
.............

at dalvik.system.VMStack.getThreadStackTrace(Native Method)
at java.lang.Thread.getStackTrace(Thread.java:595)
at android.support.test.espresso.base.DefaultFailureHandler.getUserFriendlyError(DefaultFailureHandler.java:92)
at android.support.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:56)
at android.support.test.espresso.ViewInteraction.runSynchronouslyOnUiThread(ViewInteraction.java:184)
at android.support.test.espresso.ViewInteraction.check(ViewInteraction.java:158)
at BaseOpration.AiFinder.checkMatch(AiFinder.java:49)
at com.hongfans.rearview.AutomationEspressoTest.testLogin(AutomationEspressoTest.java:63)
at java.lang.reflect.Method.invoke(Native Method)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55)
at android.support.test.rule.ActivityTestRule$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:1904)

Tests ran to completion.

Shouldn't it try to find the view every 1 second? And if failed(because I shut down the network), give me a tag false, and raise the Exception("Can not find the view")? Hope someone can help me out(if I have made any code mistaken). Much Appreciate in advance.:)

Answer 1

Actually onView itself will not search for a view - it will just prepare a ViewInteraction object that can be used by check and perform methods. In your case, instead of:

try {
    return onView(matcher);
}
...

It could be:

try {
    onView(matcher).check(matches(isDisplayed());
    return true;
}
...

However, a better approach would be to use an idling resource waiting for your view to appear. Please check this for more insight - Android test with Espresso IdlingResource