Refactor CaptionAppearanceFragment to improve maintainability (1/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 preview preference 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: Ie8acdcb8659606ce3faf6d5532cc73ee19024725

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

@@ -0,0 +1,104 @@
+/*
+ * 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 org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.view.View;
+import android.view.accessibility.CaptioningManager;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import com.android.internal.widget.SubtitleView;
+import com.android.settings.R;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.Spy;
+import org.mockito.junit.MockitoJUnit;
+import org.mockito.junit.MockitoRule;
+import org.robolectric.RobolectricTestRunner;
+
+import java.util.Locale;
+
+/** Tests for {@link CaptionHelper}. */
+@RunWith(RobolectricTestRunner.class)
+public class CaptionHelperTest {
+
+    @Rule
+    public final MockitoRule mMockitoRule = MockitoJUnit.rule();
+    @Mock
+    private CaptioningManager mCaptioningManager;
+    @Mock
+    private SubtitleView mSubtitleView;
+    @Mock
+    private View mPreviewWindow;
+    @Spy
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+    private CaptionHelper mCaptionHelper;
+
+    @Before
+    public void setUp() {
+        when(mContext.getSystemService(CaptioningManager.class)).thenReturn(mCaptioningManager);
+        mCaptionHelper = new CaptionHelper(mContext);
+    }
+
+    @Test
+    public void applyCaptionProperties_verifyAction() {
+        final float fontScale = 1.0f;
+        when(mCaptioningManager.getFontScale()).thenReturn(fontScale);
+        final int windowSize = 100;
+        when(mPreviewWindow.getWidth()).thenReturn(windowSize);
+        when(mPreviewWindow.getHeight()).thenReturn(windowSize);
+        final float textSize = CaptionHelper.LINE_HEIGHT_RATIO * windowSize * fontScale;
+
+        mCaptionHelper.applyCaptionProperties(mSubtitleView, mPreviewWindow, /* styleId= */ 0);
+
+        verify(mSubtitleView).setTextSize(textSize);
+        verify(mSubtitleView).setText(R.string.captioning_preview_characters);
+    }
+
+    @Test
+    public void applyCaptionProperties_withoutPreviewWindow_verifyAction() {
+        final float fontScale = 1.0f;
+        when(mCaptioningManager.getFontScale()).thenReturn(fontScale);
+        final float textSize = mContext.getResources().getDimension(
+                R.dimen.caption_preview_text_size) * fontScale;
+
+        mCaptionHelper.applyCaptionProperties(mSubtitleView, /* PreviewWindow= */ null,
+                /* styleId= */ 0);
+
+        verify(mSubtitleView).setTextSize(textSize);
+        verify(mSubtitleView).setText(R.string.captioning_preview_characters);
+    }
+
+    @Test
+    public void applyCaptionProperties_localeUS_verifyAction() {
+        when(mCaptioningManager.getLocale()).thenReturn(Locale.US);
+        final String text = mContext.getString(R.string.captioning_preview_characters);
+
+        mCaptionHelper.applyCaptionProperties(mSubtitleView, /* PreviewWindow= */ null,
+                /* styleId= */ 0);
+
+        verify(mSubtitleView).setText(text);
+    }
+}