New feature “Text and reading options” for SetupWizard, Wallpaper, and Settings (4/n).

- Extending the interface of AppGridView to be flexible. It will be used
in the TextReadingPreferenceFragment.
  1. Add a new attribute "appCounts" into the view.
  2. Default app counts as 6 if not set the attribute.

Bug: 211503117
Test: make -j64 RunSettingsRoboTests ROBOTEST_FILTER=AppGridViewTest
Change-Id: I94a5f1d037551f6faba0300a176feb11fba1f203

tests/robotests/src/com/android/settings/display/AppGridViewTest.java

@@ -18,26 +18,39 @@ package com.android.settings.display;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
 
 import android.content.Context;
+import android.content.Intent;
 import android.content.pm.ActivityInfo;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
 import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
 import android.util.IconDrawableFactory;
 
+import com.android.settings.R;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
+import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
 
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Tests for {@link AppGridView}.
+ */
 @RunWith(RobolectricTestRunner.class)
 public class AppGridViewTest {
 
@@ -87,4 +100,72 @@ public class AppGridViewTest {
         assertThat(entry1.compareTo(entry2)).isEqualTo(0);
         assertThat(entry1.compareTo(entry3)).isNotEqualTo(0);
     }
+
+    @Test
+    public void noAppCountAttribute_matchListSize() {
+        final int appCountFromSystem = 8;
+        setUpResolveInfos(appCountFromSystem);
+
+        final AppGridView appGridView = new AppGridView(mContext, /* attrs= */ null);
+
+        assertThat(appGridView.getAdapter().getCount()).isEqualTo(/* expected= */ 6);
+    }
+
+    @Test
+    public void setAppCountAttribute_matchListSize() {
+        final int appCountFromSystem = 8;
+        final int appCountFromAttr = 7;
+        setUpResolveInfos(appCountFromSystem);
+
+        final AppGridView appGridView =
+                new AppGridView(mContext, createAttributeSet(appCountFromAttr));
+
+        assertThat(appGridView.getAdapter().getCount()).isEqualTo(appCountFromAttr);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void setAppCountAttribute_belowLowerBound_matchListSize() {
+        final int appCountFromSystem = 9;
+        final int appCountFromAttr = -1; // The num is just for the test.
+        setUpResolveInfos(appCountFromSystem);
+
+        new AppGridView(mContext, createAttributeSet(appCountFromAttr));
+    }
+
+    @Test
+    public void setAppCountAttribute_aboveUpperBound_matchListSize() {
+        final int appCountFromSystem = 10;
+        final int appCountFromAttr = 15;
+        setUpResolveInfos(appCountFromSystem);
+
+        final AppGridView appGridView =
+                new AppGridView(mContext, createAttributeSet(appCountFromAttr));
+
+        assertThat(appGridView.getAdapter().getCount()).isEqualTo(appCountFromSystem);
+    }
+
+    private AttributeSet createAttributeSet(int appCount) {
+        return Robolectric.buildAttributeSet()
+                .addAttribute(R.attr.appCount, String.valueOf(appCount))
+                .build();
+    }
+
+    private void setUpResolveInfos(int appCount) {
+        when(mContext.getPackageManager().queryIntentActivities(
+                any(Intent.class), anyInt()))
+                .thenReturn(createFakeResolveInfos(appCount));
+    }
+
+    private List<ResolveInfo> createFakeResolveInfos(int count) {
+        final List<ResolveInfo> list = new ArrayList<>();
+
+        for (int i = 0; i < count; i++) {
+            final ResolveInfo info = new ResolveInfo();
+            info.nonLocalizedLabel = String.valueOf(i);
+
+            list.add(info);
+        }
+
+        return list;
+    }
 }