Using Android UI Automator to test content on a secondary display

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I have a barebones app written to test support for multiple displays. My setup is a custom Android tablet running Android 8.1.0 (the "primary display") connected to a touchscreen (the "secondary display") via HDMI (to deliver video signal) and USB (to deliver touch events).

The app contains a single activity, which displays "Hello World!" on the primary display but also leverages DisplayManager and WindowManager to add a counter and two + / - buttons to the secondary display:

Running the app normally and interacting with the buttons on the secondary display works as expected.

Now, I want to use UI Automator to, say, click the + button and verify that the the counter records the correct value. This appears to be impossible. Does anyone know how I can do this?

Alternatively, if UI Automator is not the right tool for the job, but there is some other tool that will let me write end-to-end black box-style tests for apps that display content on a secondary display, I am happy to get recommendations.

Some things I've investigated

I've used the uiautomatorviewer tool to inspect the layout hierarchy of my app. Only the content on the primary display is visible with this tool:

enter image description here

I've used UiDevice.dumpWindowHierarchy() to get a text dump of everything on the device. Only the content on the primary device is dumped, though this includes information about system windows like the status bar and navigation bar.

I've used adb shell dumpsys window (with both the tokens and windows commands). This will show me information about the window that I've created on the secondary display, but I seem to have no way to access this window through Ui Automator:

Display #1
WindowToken{551f82f android.os.BinderProxy@87f65ac}:
  windows=[Window{e40e275 u0 com.example.stackoverflow}]
  windowType=2038 hidden=false hasVisible=true

Window #10 Window{20ac4ce u0 com.example.stackoverflow}:
  mDisplayId=1 mSession=Session{91fdd93 8079:u0a10089} mClient=android.os.BinderProxy@a3e65c9
  mOwnerUid=10089 mShowToOwnerOnly=true package=com.example.stackoverflow appop=SYSTEM_ALERT_WINDOW
  mAttrs=WM.LayoutParams{(0,0)(fillxfill) sim=#20 ty=2038 fl=#1280480 colorMode=0}
  Requested w=1280 h=800 mLayoutSeq=908
  mBaseLayer=121000 mSubLayer=0 mAnimLayer=121000+0=121000 mLastLayer=121000
  mToken=WindowToken{a42e219 android.os.BinderProxy@a3e65c9}
  ...

Relevant code samples

Adding the content to the secondary display (in my Activity's onResume() method):

DisplayManager manager = (DisplayManager) getApplicationContext().getSystemService(Context.DISPLAY_SERVICE);
Display display = manager.getDisplays(DisplayManager.DISPLAY_CATEGORY_PRESENTATION)[0];
Context displayContext = getApplicationContext().createDisplayContext(display);
WindowManager windowManager = (WindowManager) displayContext.getSystemService(Context.WINDOW_SERVICE);

LinearLayout root = new LinearLayout(displayContext);
WindowManager.LayoutParams params = createLayoutParams();
windowManager.addView(root, params);

View.inflate(root.getContext(), R.layout.overlay, root);
root.findViewById(R.id.minus).setOnClickListener(v -> decrementCounter());
root.findViewById(R.id.plus).setOnClickListener(v -> incrementCounter());

I'm using the Application context instead of the Activity context so that the content on the secondary display is not dependent on the lifetime of the Activity that creates it. Theoretically I could navigate to other activities and this content would remain on the secondary display and remain interactive.

Creating the LayoutParams object:

private WindowManager.LayoutParams createLayoutParams() {
    return new WindowManager.LayoutParams(
            ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT,
            0, 0,
            WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
            0,
            PixelFormat.OPAQUE
    );
}
android-uiautomator ui-automation android
1 Answers

There is Espresso which works for testing your app. The good thing is, you don't have choose which to use. You can use them both. Espresso is running in separate thread and it is really fast comparing to other test frameworks. Use both of them in your tests.

Espresso tests state expectations, interactions, and assertions clearly without the distraction of boilerplate content, custom infrastructure, or messy implementation details getting in the way.

Espresso tests run optimally fast! It lets you leave your waits, syncs, sleeps, and polls behind while it manipulates and asserts on the application UI when it is at rest.

This is Espresso's Multiprocess and this is the Cheat Sheet for Espresso.

Use Espresso with ActivityTestRule

The following section describes how to create a new Espresso test in the JUnit 4 style and use ActivityTestRule to reduce the amount of boilerplate code you need to write. By using ActivityTestRule, the testing framework launches the activity under test before each test method annotated with @Test and before any method annotated with @Before. The framework handles shutting down the activity after the test finishes and all methods annotated with @After are run.

package com.example.android.testing.espresso.BasicSample;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;

import androidx.test.rule.ActivityTestRule;
import androidx.test.runner.AndroidJUnit4;

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

    private String stringToBetyped;

    @Rule
    public ActivityTestRule<MainActivity> activityRule
            = new ActivityTestRule<>(MainActivity.class);

    @Before
    public void initValidString() {
        // Specify a valid string.
        stringToBetyped = "Espresso";
    }

    @Test
    public void changeText_sameActivity() {
        // Type text and then press the button.
        onView(withId(R.id.editTextUserInput))
                .perform(typeText(stringToBetyped), closeSoftKeyboard());
        onView(withId(R.id.changeTextBt)).perform(click());

        // Check that the text was changed.
        onView(withId(R.id.textToBeChanged))
                .check(matches(withText(stringToBetyped)));
    }
}

And if you want to learn more, here is the testing documentation

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