Initial commit for Settings component test

Test: Tested on local device
Bug: 178765084
Change-Id: I3b8f36daa31b0a44e788fe4c84f94d48653ee037

tests/componenttests/src/com/android/settings/testutils/UiUtils.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2020 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 com.android.settings.testutils;
+
+import android.app.Activity;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+import androidx.test.runner.lifecycle.ActivityLifecycleMonitorRegistry;
+import androidx.test.runner.lifecycle.Stage;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.function.Supplier;
+
+public class UiUtils {
+
+    public static void waitUntilCondition(long timeoutInMillis, Supplier<Boolean> condition) {
+        long start = System.nanoTime();
+        while (System.nanoTime() - start < (timeoutInMillis * 1000000)) {
+            try {
+                //Eat NPE from condition because there's a concurrency issue that when calling
+                //findViewById when the view hierarchy is still rendering, it sometimes encounter
+                //null views that may exist few milliseconds before, and causes a NPE.
+                if (condition.get()) {
+                    return;
+                }
+            } catch (NullPointerException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    public static boolean waitForActivitiesInStage(long timeoutInMillis, Stage stage) {
+        final Collection<Activity> activities = new ArrayList<>();
+        waitUntilCondition(Constants.ACTIVITY_LAUNCH_WAIT_TIMEOUT, () -> {
+            InstrumentationRegistry.getInstrumentation().runOnMainSync(() -> activities.addAll(
+                    ActivityLifecycleMonitorRegistry.getInstance().getActivitiesInStage(
+                            Stage.RESUMED)));
+            return activities.size() > 0;
+        });
+
+        return activities.size() > 0;
+    }
+}