Disable the usage summary when there's no usage data.

- when the preference is initialized, check for the network's overall
total usage. If there is no data available, disable launching the detail
page.

Change-Id: Ie81a5471de134bac63dedd3c39f4afe44201efe5
Fixes: 74451774
Fixes: 35855928
Test: make RunSettingsRoboTests

tests/robotests/src/com/android/settings/datausage/DataUsagePreferenceTest.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2018 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.datausage;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+import android.content.Context;
+import android.content.Intent;
+import android.net.NetworkTemplate;
+
+import com.android.settings.testutils.SettingsRobolectricTestRunner;
+import com.android.settingslib.net.DataUsageController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RuntimeEnvironment;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+public class DataUsagePreferenceTest {
+
+    @Mock
+    private DataUsageController mController;
+
+    private Context mContext;
+    private DataUsagePreference mPreference;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        mContext = RuntimeEnvironment.application;
+        mPreference = spy(new DataUsagePreference(mContext, null /* attrs */));
+        doReturn(mController).when(mPreference).getDataUsageController();
+
+    }
+
+    @Test
+    public void setTemplate_noDataUsage_shouldDisablePreference() {
+        doReturn(0L).when(mController).getHistoriclUsageLevel(any(NetworkTemplate.class));
+
+        mPreference.setTemplate(
+                NetworkTemplate.buildTemplateMobileWildcard(), 5 /* subId */, null /* services */);
+
+        verify(mPreference).setEnabled(false);
+        verify(mPreference).setIntent(null);
+    }
+
+    @Test
+    public void setTemplate_hasDataUsage_shouldNotDisablePreference() {
+        doReturn(200L).when(mController).getHistoriclUsageLevel(any(NetworkTemplate.class));
+
+        mPreference.setTemplate(
+                NetworkTemplate.buildTemplateMobileWildcard(), 5 /* subId */, null /* services */);
+
+        verify(mPreference, never()).setEnabled(false);
+        verify(mPreference).setIntent(any(Intent.class));
+    }
+}