ToastTest.java

package com.example.myapplication;

import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;
import android.util.Log;
import android.view.accessibility.AccessibilityEvent;

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

import androidx.test.core.app.ApplicationProvider;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import androidx.test.platform.app.InstrumentationRegistry;
import androidx.test.uiautomator.By;
import androidx.test.uiautomator.UiDevice;
import androidx.test.uiautomator.Until;

import static org.junit.Assert.assertTrue;

/**
 * Instrumented test, which will execute on an Android device.
 *
 * @see <a href=http://d.android.com/tools/testing>Testing documentation</a>
 */
@RunWith(AndroidJUnit4.class)
public class ToastTest {
    private static final String TAG = "TestAutomation";
    private static final long LAUNCH_TIMEOUT = 5000;
    private static final String PACKAGE_NAME = "com.example.myapplication";

    private final UiDevice device = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation());
    private boolean toastDisplayed;

    @Test
    public void testToast() {
        launchApp();
        assertTrue("Toast was not displayed", isToastDisplayed("toast test", () -> {
            device.findObject(By.res(PACKAGE_NAME + ":id/fab")).click();
        }));

    }

    private boolean isToastDisplayed(String text, Runnable action) {
        toastDisplayed = false;
        long startTimeMs = System.currentTimeMillis();
        Log.d(TAG, "isToastDisplayed: start waiting");
        InstrumentationRegistry.getInstrumentation().getUiAutomation()
                .setOnAccessibilityEventListener((event) -> {
                    Log.d(TAG, "isToastDisplayed: event");
                    if (event.getEventType() == AccessibilityEvent.TYPE_NOTIFICATION_STATE_CHANGED
                            && PACKAGE_NAME.equals(event.getPackageName().toString())
                            && event.getClassName().toString().contains(android.widget.Toast.class.getName())
                            && ("[" + text + "]").equals(event.getText().toString())
                    )
                    {
                        Log.d(TAG, "isToastDisplayed: TOAST");
                        toastDisplayed = true;
                    }
                    event.recycle();
                });
        action.run();
        while (!toastDisplayed && System.currentTimeMillis() - startTimeMs < 10000) {
            Log.d(TAG, "isToastDisplayed: sleep");
            SystemClock.sleep(500); }
        InstrumentationRegistry.getInstrumentation().getUiAutomation().setOnAccessibilityEventListener(null);
        return toastDisplayed;
    }

    private void launchApp() {
        Context context = ApplicationProvider.getApplicationContext();
        final Intent intent = context.getPackageManager().getLaunchIntentForPackage(PACKAGE_NAME);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
        context.startActivity(intent);
        device.wait(Until.hasObject(By.pkg(PACKAGE_NAME).depth(0)), LAUNCH_TIMEOUT);
    }
}