Add test to verify no crash on selecting brightness level.

Add UI test to launch Settings->Display->Brightness level and Settings
app does not crash.

Change-Id: I526f44961bd0efbcacde334affbe2b7a93da0ce3
Fix: 36647069
Test: make SettingsTests
diff --git a/tests/app/src/com/android/settings/DisplaySettingsTest.java b/tests/app/src/com/android/settings/DisplaySettingsTest.java
new file mode 100644
index 0000000..888b7fd
--- /dev/null
+++ b/tests/app/src/com/android/settings/DisplaySettingsTest.java
@@ -0,0 +1,57 @@
+/*
+ * 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 com.android.settings;
+
+import static android.support.test.espresso.Espresso.onView;
+import static android.support.test.espresso.action.ViewActions.click;
+import static android.support.test.espresso.matcher.ViewMatchers.withText;
+
+import android.app.Instrumentation;
+import android.content.Context;
+import android.content.Intent;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+import android.support.test.uiautomator.UiDevice;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class DisplaySettingsTest {
+
+    private Instrumentation mInstrumentation;
+    private Context mContext;
+    private UiDevice mDevice;
+
+    @Before
+    public void setUp() {
+        mInstrumentation = InstrumentationRegistry.getInstrumentation();
+        mContext = mInstrumentation.getTargetContext();
+        mDevice = UiDevice.getInstance(mInstrumentation);
+    }
+
+    @Test
+    public void launchBrightnessLevel_shouldNotCrash() {
+        mInstrumentation.startActivitySync(
+                new Intent(mContext, DisplaySettings.class));
+        onView(withText(mContext.getString(R.string.brightness))).perform(click());
+        // should not crash
+        mDevice.pressBack(); // dismiss the brightness dialog
+    }
+}