Refactor CaptionAppearanceFragment to improve maintainability (5/n)

Root cause: There is a bunch of different logic of preferences in CaptionAppearanceFragment. It’s hard to implement new features and hard to maintain and hard to be testable.
Solution: Move out custom perference visiblity logic of CaptionAppearanceFragment into controllers to reduce the complexity of the relationship between preference and fragment.

Bug: 197695932
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.accessibility
Change-Id: I53d4ca3809031587f8d6853b427774fd322a71d8

tests/robotests/src/com/android/settings/accessibility/CaptionCustomControllerTest.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2022 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.accessibility;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.provider.Settings;
+import android.view.accessibility.CaptioningManager.CaptionStyle;
+
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+import androidx.test.core.app.ApplicationProvider;
+
+import com.android.settings.core.BasePreferenceController;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+import org.robolectric.RobolectricTestRunner;
+
+/** Tests for {@link CaptionCustomController}. */
+@RunWith(RobolectricTestRunner.class)
+public class CaptionCustomControllerTest {
+
+    private static final String PREF_KEY = "custom";
+
+    @Rule
+    public final MockitoRule mMockitoRule = MockitoJUnit.rule();
+    @Mock
+    private PreferenceScreen mScreen;
+    @Mock
+    private AccessibilitySettingsContentObserver mAccessibilitySettingsContentObserver;
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+    private ContentResolver mContentResolver;
+    private CaptionCustomController mController;
+    private Preference mPreference;
+
+    @Before
+    public void setUp() {
+        mContentResolver = mContext.getContentResolver();
+        mController = new CaptionCustomController(mContext, PREF_KEY,
+                mAccessibilitySettingsContentObserver);
+        mPreference = new Preference(mContext);
+        when(mScreen.findPreference(mController.getPreferenceKey())).thenReturn(mPreference);
+    }
+
+    @Test
+    public void getAvailabilityStatus_shouldReturnAvailable() {
+        assertThat(mController.getAvailabilityStatus())
+                .isEqualTo(BasePreferenceController.AVAILABLE);
+    }
+
+
+    @Test
+    public void displayPreference_byDefault_shouldIsInvisible() {
+        mController.displayPreference(mScreen);
+
+        assertThat(mPreference.isVisible()).isFalse();
+    }
+
+    @Test
+    public void displayPreference_customValue_shouldIsVisible() {
+        Settings.Secure.putInt(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_CAPTIONING_PRESET, CaptionStyle.PRESET_CUSTOM);
+
+        mController.displayPreference(mScreen);
+
+        assertThat(mPreference.isVisible()).isTrue();
+    }
+
+    @Test
+    public void onStart_registerSpecificContentObserverForSpecificKeys() {
+        mController.onStart();
+
+        verify(mAccessibilitySettingsContentObserver).register(mContentResolver);
+    }
+
+    @Test
+    public void onStop_unregisterContentObserver() {
+        mController.onStop();
+
+        verify(mAccessibilitySettingsContentObserver).unregister(mContentResolver);
+    }
+}