Add view waiting function as test util

The added function |waitForView| repeatedly checks all views in a group
until either a view was found that matches the given matcher.
If this doesn't happen within a certain time or multiple views are
matched, it fails the test.

This simplifies UI tests by:
 - reducing flakiness, e.g. introduced due to animations
 - removing the need for sleeps or other timers.
 - reducing code duplication due to providing a central implementation

Upcoming CLs that would benefit greatly from this:
https://crrev.com/c/951588 and https://crrev.com/c/951764

Change-Id: Ibb6a0dcd2eb688467c4af1eaa82341f84e7e8bc6
Reviewed-on: https://chromium-review.googlesource.com/951688
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542172}

chrome/android/javatests/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferencesTest.java

@@ -36,6 +36,8 @@ import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.startsWith;
 
+import static org.chromium.chrome.test.util.ViewUtils.waitForView;
+
 import android.app.Activity;
 import android.app.Instrumentation;
 import android.content.Intent;
@@ -44,14 +46,11 @@ import android.support.annotation.IntDef;
 import android.support.annotation.Nullable;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.espresso.Espresso;
-import android.support.test.espresso.PerformException;
-import android.support.test.espresso.UiController;
-import android.support.test.espresso.ViewAction;
 import android.support.test.espresso.intent.Intents;
-import android.support.test.espresso.util.TreeIterables;
 import android.support.test.filters.SmallTest;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.ViewGroup;
 import android.widget.LinearLayout;
 
 import org.hamcrest.Matcher;
@@ -81,7 +80,6 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.concurrent.TimeoutException;
 
 /**
  * Tests for the "Save Passwords" settings screen.
@@ -333,39 +331,6 @@ public class SavePasswordsPreferencesTest {
             Thread.sleep(100);
     }
 
-    /**
-     * Waits until a view matching the given matcher appears. Times out if no view was found until
-     * the UI_UPDATING_TIMEOUT_MS expired.
-     * @param viewMatcher The matcher matching the view that should be waited for.
-     */
-    private void waitForView(Matcher<View> viewMatcher) {
-        Espresso.onView(isRoot()).perform(new ViewAction() {
-            @Override
-            public Matcher<View> getConstraints() {
-                return isRoot();
-            }
-
-            @Override
-            public String getDescription() {
-                return "wait for " + UI_UPDATING_TIMEOUT_MS + "ms to match "
-                        + viewMatcher.toString();
-            }
-
-            @Override
-            public void perform(UiController uiController, View root) {
-                final long start_time = System.currentTimeMillis();
-                do {
-                    for (View view : TreeIterables.breadthFirstViewTraversal(root))
-                        if (viewMatcher.matches(view)) return;
-                    uiController.loopMainThreadForAtLeast(100);
-                } while (System.currentTimeMillis() - start_time < UI_UPDATING_TIMEOUT_MS);
-                throw new PerformException.Builder()
-                        .withActionDescription(this.getDescription())
-                        .withCause(new TimeoutException())
-                        .build();
-            }
-        });
-    }
 
     /**
      * Ensure that resetting of empty passwords list works.
@@ -1590,12 +1555,15 @@ public class SavePasswordsPreferencesTest {
         ReauthenticationManager.setApiOverride(ReauthenticationManager.OVERRIDE_STATE_AVAILABLE);
         ReauthenticationManager.setScreenLockSetUpOverride(
                 ReauthenticationManager.OVERRIDE_STATE_AVAILABLE);
-        PreferencesTest.startPreferences(InstrumentationRegistry.getInstrumentation(),
-                SavePasswordsPreferences.class.getName());
+        final Preferences prefs =
+                PreferencesTest.startPreferences(InstrumentationRegistry.getInstrumentation(),
+                        SavePasswordsPreferences.class.getName());
 
         // Open the search and filter all but "Zeus".
         Espresso.onView(withSearchMenuIdOrText()).perform(click());
-        waitForView(withId(R.id.search_src_text));
+
+        Espresso.onView(isRoot()).check(
+                (root, e) -> waitForView((ViewGroup) root, withId(R.id.search_src_text)));
         Espresso.onView(withId(R.id.search_src_text))
                 .perform(click(), typeText("Zeu"), closeSoftKeyboard());
         InstrumentationRegistry.getInstrumentation().waitForIdleSync();
@@ -1632,7 +1600,10 @@ public class SavePasswordsPreferencesTest {
         InstrumentationRegistry.getInstrumentation().waitForIdleSync();
 
         // The search bar should still be open and still display the search query.
-        waitForView(allOf(withId(R.id.search_src_text), withText("Zeu")));
+        Espresso.onView(isRoot()).check(
+                (root, e)
+                        -> waitForView((ViewGroup) root,
+                                allOf(withId(R.id.search_src_text), withText("Zeu"))));
         Espresso.onView(withId(R.id.search_src_text)).check(matches(withText("Zeu")));
     }
 
@@ -1673,7 +1644,9 @@ public class SavePasswordsPreferencesTest {
         InstrumentationRegistry.getInstrumentation().removeMonitor(monitor);
         Espresso.onView(withContentDescription(R.string.abc_action_bar_up_description))
                 .perform(click()); // Go back to the search list.
-        waitForView(withId(R.id.search_src_text));
+        Espresso.onView(isRoot()).check(
+                (root, e) -> waitForView((ViewGroup) root, withId(R.id.search_src_text)));
+
         Assert.assertEquals(1, viewed_after_search_delta.getDelta());
 
         preferences.finish();

chrome/test/android/BUILD.gn

@@ -54,6 +54,7 @@ android_library("chrome_java_test_support") {
     "javatests/src/org/chromium/chrome/test/util/ChromeSigninUtils.java",
     "javatests/src/org/chromium/chrome/test/util/ChromeTabUtils.java",
     "javatests/src/org/chromium/chrome/test/util/DisableInTabbedMode.java",
+    "javatests/src/org/chromium/chrome/test/util/ViewUtils.java",
     "javatests/src/org/chromium/chrome/test/util/FullscreenTestUtils.java",
     "javatests/src/org/chromium/chrome/test/util/InfoBarTestAnimationListener.java",
     "javatests/src/org/chromium/chrome/test/util/InfoBarUtil.java",
@@ -96,6 +97,7 @@ android_library("chrome_java_test_support") {
     "//third_party/android_tools:android_support_design_java",
     "//third_party/android_tools:android_support_v7_appcompat_java",
     "//third_party/android_tools:android_support_v7_recyclerview_java",
+    "//third_party/hamcrest:hamcrest_core_java",
     "//third_party/jsr-305:jsr_305_javalib",
     "//third_party/junit",
     "//third_party/ub-uiautomator:ub_uiautomator_java",

chrome/test/android/javatests/src/org/chromium/chrome/test/util/ViewUtils.java

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.test.util;
+
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+import android.support.annotation.IntDef;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.hamcrest.Matcher;
+
+import org.chromium.content.browser.test.util.Criteria;
+import org.chromium.content.browser.test.util.CriteriaHelper;
+
+import java.lang.annotation.Retention;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Collection of utilities helping to clarify expectations on views in tests.
+ */
+public class ViewUtils {
+    @Retention(SOURCE)
+    @IntDef(flag = true, value = {VIEW_VISIBLE, VIEW_INVISIBLE, VIEW_GONE, VIEW_NULL})
+    public @interface ExpectedViewState {}
+    public static final int VIEW_VISIBLE = 1;
+    public static final int VIEW_INVISIBLE = 1 << 1;
+    public static final int VIEW_GONE = 1 << 2;
+    public static final int VIEW_NULL = 1 << 3;
+
+    private static class ExpectedViewCriteria extends Criteria {
+        private final Matcher<View> mViewMatcher;
+        private final @ExpectedViewState int mViewState;
+        private final ViewGroup mRootView;
+
+        ExpectedViewCriteria(
+                Matcher<View> viewMatcher, @ExpectedViewState int viewState, ViewGroup rootView) {
+            mViewMatcher = viewMatcher;
+            mViewState = viewState;
+            mRootView = rootView;
+        }
+
+        @Override
+        public boolean isSatisfied() {
+            List<View> matchedViews = new ArrayList<>();
+            findMatchingChildren(mRootView, matchedViews);
+            if (matchedViews.size() > 1) {
+                updateFailureReason("Multiple views matched: " + mViewMatcher.toString());
+                return false;
+            }
+            return matchedViews.size() == 0 ? hasViewExpectedState(null)
+                                            : hasViewExpectedState(matchedViews.get(0));
+        }
+
+        private void findMatchingChildren(ViewGroup root, List<View> matchedViews) {
+            for (int i = 0; i < root.getChildCount(); i++) {
+                View view = root.getChildAt(i);
+                if (mViewMatcher.matches(view)) matchedViews.add(view);
+                if (view instanceof ViewGroup) {
+                    findMatchingChildren((ViewGroup) view, matchedViews);
+                }
+            };
+        }
+
+        private boolean hasViewExpectedState(View view) {
+            if (view == null) {
+                updateFailureReason("No matching view was found!");
+                return (mViewState & VIEW_NULL) != 0;
+            }
+            switch (view.getVisibility()) {
+                case View.VISIBLE:
+                    updateFailureReason("Found view is unexpectedly visible!");
+                    return (mViewState & VIEW_VISIBLE) != 0;
+                case View.INVISIBLE:
+                    updateFailureReason("Found view is unexpectedly invisible!");
+                    return (mViewState & VIEW_INVISIBLE) != 0;
+                case View.GONE:
+                    updateFailureReason("Found view is unexpectedly gone!");
+                    return (mViewState & VIEW_GONE) != 0;
+            }
+            assert false; // Not Reached.
+            return false;
+        }
+    }
+
+    private ViewUtils() {}
+
+    /**
+     * Waits until a view matching the given matches any of the given {@link ExpectedViewState}s.
+     * Fails if the matcher applies to multiple views. Times out if no view was found while waiting
+     * up to
+     * {@link CriteriaHelper#DEFAULT_MAX_TIME_TO_POLL} milliseconds.
+     * @param root The view group to search in.
+     * @param viewMatcher The matcher matching the view that should be waited for.
+     * @param viewState State that the matching view should be in. If multiple states are passed,
+     *                  the waiting will stop if at least one applies.
+     */
+    public static void waitForView(
+            ViewGroup root, Matcher<View> viewMatcher, @ExpectedViewState int viewState) {
+        CriteriaHelper.pollUiThread(new ExpectedViewCriteria(viewMatcher, viewState, root));
+    }
+
+    /**
+     * Waits until a visible view matching the given matcher appears. Fails if the matcher applies
+     * to multiple views.  Times out if no view was found while waiting up to
+     * {@link CriteriaHelper#DEFAULT_MAX_TIME_TO_POLL} milliseconds.
+     * @param root The view group to search in.
+     * @param viewMatcher The matcher matching the view that should be waited for.
+     */
+    public static void waitForView(ViewGroup root, Matcher<View> viewMatcher) {
+        waitForView(root, viewMatcher, VIEW_VISIBLE);
+    }
+}