DataUsageSummaryPreferenceTest converted to JUnit

There are couple of newly explored concepts in this CL, which will
hopefully be useful for migrating other tests in the future as well. In
broad strokes, the changes to this file cover:

Android build file species the preferences library, in order to access
PreferenceViewHolder.createInstanceForTests.
Resource ids in JUnit tests differ from the Settings apk. This is true
not only of strings but also views and layouts. Helper functions added
to main class to access the layouts needed by the test.
Shadow activities are not needed to view layouts, the context can be
used.
Context startActivity can be mocked and verified in order to capture and
examine the intent created by the library under test.

Bug: 175389659
Test: atest -c DataUsageSummaryPreferenceTest
Change-Id: Ib8cb87f0299c47a32c3f5d3af7edb20592b727ec

src/com/android/settings/datausage/DataUsageSummaryPreference.java

@@ -32,6 +32,7 @@ import android.text.style.AbsoluteSizeSpan;
 import android.util.AttributeSet;
 import android.view.View;
 import android.widget.Button;
+import android.widget.LinearLayout;
 import android.widget.ProgressBar;
 import android.widget.TextView;
 
@@ -156,24 +157,24 @@ public class DataUsageSummaryPreference extends Preference {
     public void onBindViewHolder(PreferenceViewHolder holder) {
         super.onBindViewHolder(holder);
 
-        ProgressBar bar = (ProgressBar) holder.findViewById(R.id.determinateBar);
+        ProgressBar bar = getProgressBar(holder);
         if (mChartEnabled && (!TextUtils.isEmpty(mStartLabel) || !TextUtils.isEmpty(mEndLabel))) {
             bar.setVisibility(View.VISIBLE);
-            holder.findViewById(R.id.label_bar).setVisibility(View.VISIBLE);
+            getLabelBar(holder).setVisibility(View.VISIBLE);
             bar.setProgress((int) (mProgress * 100));
-            ((TextView) holder.findViewById(android.R.id.text1)).setText(mStartLabel);
-            ((TextView) holder.findViewById(android.R.id.text2)).setText(mEndLabel);
+            (getLabel1(holder)).setText(mStartLabel);
+            (getLabel2(holder)).setText(mEndLabel);
         } else {
             bar.setVisibility(View.GONE);
-            holder.findViewById(R.id.label_bar).setVisibility(View.GONE);
+            getLabelBar(holder).setVisibility(View.GONE);
         }
 
         updateDataUsageLabels(holder);
 
-        TextView usageTitle = (TextView) holder.findViewById(R.id.usage_title);
-        TextView carrierInfo = (TextView) holder.findViewById(R.id.carrier_and_update);
-        Button launchButton = (Button) holder.findViewById(R.id.launch_mdp_app_button);
-        TextView limitInfo = (TextView) holder.findViewById(R.id.data_limits);
+        TextView usageTitle = getUsageTitle(holder);
+        TextView carrierInfo = getCarrierInfo(holder);
+        Button launchButton = getLaunchButton(holder);
+        TextView limitInfo = getDataLimits(holder);
 
         if (mWifiMode && mSingleWifi) {
             updateCycleTimeText(holder);
@@ -187,7 +188,7 @@ public class DataUsageSummaryPreference extends Preference {
         } else if (mWifiMode) {
             usageTitle.setText(R.string.data_usage_wifi_title);
             usageTitle.setVisibility(View.VISIBLE);
-            TextView cycleTime = (TextView) holder.findViewById(R.id.cycle_left_time);
+            TextView cycleTime = getCycleTime(holder);
             cycleTime.setText(mUsagePeriod);
             carrierInfo.setVisibility(View.GONE);
             limitInfo.setVisibility(View.GONE);
@@ -235,7 +236,7 @@ public class DataUsageSummaryPreference extends Preference {
     }
 
     private void updateDataUsageLabels(PreferenceViewHolder holder) {
-        TextView usageNumberField = (TextView) holder.findViewById(R.id.data_usage_view);
+        TextView usageNumberField = getDataUsed(holder);
 
         final Formatter.BytesResult usedResult = Formatter.formatBytes(getContext().getResources(),
                 mDataplanUse, Formatter.FLAG_CALCULATE_ROUNDED | Formatter.FLAG_IEC_UNITS);
@@ -250,11 +251,10 @@ public class DataUsageSummaryPreference extends Preference {
                 TextUtils.expandTemplate(template, usageNumberText, usedResult.units);
         usageNumberField.setText(usageText);
 
-        final MeasurableLinearLayout layout =
-                (MeasurableLinearLayout) holder.findViewById(R.id.usage_layout);
+        final MeasurableLinearLayout layout = getLayout(holder);
 
         if (mHasMobileData && mNumPlans >= 0 && mDataplanSize > 0L) {
-            TextView usageRemainingField = (TextView) holder.findViewById(R.id.data_remaining_view);
+            TextView usageRemainingField = getDataRemaining(holder);
             long dataRemaining = mDataplanSize - mDataplanUse;
             if (dataRemaining >= 0) {
                 usageRemainingField.setText(
@@ -276,7 +276,7 @@ public class DataUsageSummaryPreference extends Preference {
     }
 
     private void updateCycleTimeText(PreferenceViewHolder holder) {
-        TextView cycleTime = (TextView) holder.findViewById(R.id.cycle_left_time);
+        TextView cycleTime = getCycleTime(holder);
 
         // Takes zero as a special case which value is never set.
         if (mCycleEndTimeMs == CYCLE_TIME_UNINITIAL_VALUE) {
@@ -362,9 +362,68 @@ public class DataUsageSummaryPreference extends Preference {
     }
 
     @VisibleForTesting
-    long getHistoricalUsageLevel() {
+    protected long getHistoricalUsageLevel() {
         final DataUsageController controller = new DataUsageController(getContext());
         return controller.getHistoricalUsageLevel(NetworkTemplate.buildTemplateWifiWildcard());
     }
 
+    @VisibleForTesting
+    protected TextView getUsageTitle(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.usage_title);
+    }
+
+    @VisibleForTesting
+    protected TextView getCycleTime(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.cycle_left_time);
+    }
+
+    @VisibleForTesting
+    protected TextView getCarrierInfo(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.carrier_and_update);
+    }
+
+    @VisibleForTesting
+    protected TextView getDataLimits(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.data_limits);
+    }
+
+    @VisibleForTesting
+    protected TextView getDataUsed(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.data_usage_view);
+    }
+
+    @VisibleForTesting
+    protected TextView getDataRemaining(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(R.id.data_remaining_view);
+    }
+
+    @VisibleForTesting
+    protected Button getLaunchButton(PreferenceViewHolder holder) {
+        return (Button) holder.findViewById(R.id.launch_mdp_app_button);
+    }
+
+    @VisibleForTesting
+    protected LinearLayout getLabelBar(PreferenceViewHolder holder) {
+        return (LinearLayout) holder.findViewById(R.id.label_bar);
+    }
+
+    @VisibleForTesting
+    protected TextView getLabel1(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(android.R.id.text1);
+    }
+
+    @VisibleForTesting
+    protected TextView getLabel2(PreferenceViewHolder holder) {
+        return (TextView) holder.findViewById(android.R.id.text2);
+    }
+
+    @VisibleForTesting
+    protected ProgressBar getProgressBar(PreferenceViewHolder holder) {
+        return (ProgressBar) holder.findViewById(R.id.determinateBar);
+    }
+
+    @VisibleForTesting
+    protected MeasurableLinearLayout getLayout(PreferenceViewHolder holder) {
+        return (MeasurableLinearLayout) holder.findViewById(R.id.usage_layout);
+    }
 }