android/support/wear/widget/util/AsyncViewActions.java

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.support.wear.widget.util;

import android.support.test.espresso.PerformException;
import android.support.test.espresso.UiController;
import android.support.test.espresso.ViewAction;
import android.support.test.espresso.util.HumanReadables;
import android.support.test.espresso.util.TreeIterables;
import android.view.View;

import org.hamcrest.Matchers;
import org.hamcrest.StringDescription;

import java.util.concurrent.TimeoutException;

public class AsyncViewActions {

    /** Perform action of waiting for a specific view id. */
    public static ViewAction waitForMatchingView(
            final org.hamcrest.Matcher<? extends View> viewMatcher, final long millis) {
        return new ViewAction() {
            @Override
            public void perform(UiController uiController, View view) {
                uiController.loopMainThreadUntilIdle();
                final long startTime = System.currentTimeMillis();
                final long endTime = startTime + millis;
                do {
                    for (View child : TreeIterables.breadthFirstViewTraversal(view)) {
                        // found matching view
                        if (viewMatcher.matches(child)) {
                            return;
                        }
                    }
                    uiController.loopMainThreadForAtLeast(100); // at least 3 frames
                } while (System.currentTimeMillis() < endTime);

                // timeout happens
                throw new PerformException.Builder()
                        .withActionDescription(this.getDescription())
                        .withViewDescription(HumanReadables.describe(view))
                        .withCause(new TimeoutException())
                        .build();
            }

            @Override
            public String getDescription() {
                return "Wait for view which matches " + StringDescription.asString(viewMatcher);
            }

            @Override
            public org.hamcrest.Matcher<View> getConstraints() {
                return Matchers.any(View.class);
            }
        };
    }
}