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Testing TTML Style Resolution Implementation in SmartTube

This test suite validates the TTML (Timed Text Markup Language) rendering utilities in ExoPlayer, focusing on style resolution and inheritance mechanisms. The tests verify how different TTML styles are merged and applied in various scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of TTML style resolution scenarios including:

Empty style handling
Single referential style resolution
Multiple style inheritance and merging
Inline style handling with referential styles
Style attribute preservation and override behavior

Implementation Analysis

The testing approach uses JUnit with AndroidJUnit4 runner for Android-specific color handling. Tests employ a systematic pattern of creating style combinations and verifying attribute inheritance, using Truth assertions for clear test validation.

Each test case isolates specific style resolution scenarios, from basic null handling to complex multi-style merging.

Technical Details

Testing Framework:

JUnit 4 with AndroidJUnit4 runner
Google Truth assertion library
Android graphics Color utilities
HashMap for global style management

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases with clear purpose
Comprehensive edge case coverage
Helper methods for test data setup
Consistent assertion patterns
Clear test naming conventions

yuliskov/smarttube

exoplayer-amzn-2.10.6/library/core/src/test/java/com/google/android/exoplayer2/text/ttml/TtmlRenderUtilTest.java

            
/*
 * Copyright (C) 2016 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.google.android.exoplayer2.text.ttml;

import static android.graphics.Color.BLACK;
import static android.graphics.Color.RED;
import static android.graphics.Color.YELLOW;
import static com.google.android.exoplayer2.text.ttml.TtmlRenderUtil.resolveStyle;
import static com.google.android.exoplayer2.text.ttml.TtmlStyle.STYLE_BOLD;
import static com.google.android.exoplayer2.text.ttml.TtmlStyle.STYLE_BOLD_ITALIC;
import static com.google.common.truth.Truth.assertThat;

import android.graphics.Color;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import java.util.HashMap;
import java.util.Map;
import org.junit.Test;
import org.junit.runner.RunWith;

/** Unit test for {@link TtmlRenderUtil}. */
@RunWith(AndroidJUnit4.class)
public final class TtmlRenderUtilTest {

  @Test
  public void testResolveStyleNoStyleAtAll() {
    assertThat(resolveStyle(null, null, null)).isNull();
  }

  @Test
  public void testResolveStyleSingleReferentialStyle() {
    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
    String[] styleIds = {"s0"};

    assertThat(TtmlRenderUtil.resolveStyle(null, styleIds, globalStyles))
        .isSameAs(globalStyles.get("s0"));
  }

  @Test
  public void testResolveStyleMultipleReferentialStyles() {
    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
    String[] styleIds = {"s0", "s1"};

    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(null, styleIds, globalStyles);
    assertThat(resolved).isNotSameAs(globalStyles.get("s0"));
    assertThat(resolved).isNotSameAs(globalStyles.get("s1"));
    assertThat(resolved.getId()).isNull();

    // inherited from s0
    assertThat(resolved.getBackgroundColor()).isEqualTo(BLACK);
    // inherited from s1
    assertThat(resolved.getFontColor()).isEqualTo(RED);
    // merged from s0 and s1
    assertThat(resolved.getStyle()).isEqualTo(STYLE_BOLD_ITALIC);
  }

  @Test
  public void testResolveMergeSingleReferentialStyleIntoInlineStyle() {
    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
    String[] styleIds = {"s0"};
    TtmlStyle style = new TtmlStyle();
    style.setBackgroundColor(Color.YELLOW);

    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(style, styleIds, globalStyles);
    assertThat(resolved).isSameAs(style);

    // inline attribute not overridden
    assertThat(resolved.getBackgroundColor()).isEqualTo(YELLOW);
    // inherited from referential style
    assertThat(resolved.getStyle()).isEqualTo(STYLE_BOLD);
  }

  @Test
  public void testResolveMergeMultipleReferentialStylesIntoInlineStyle() {
    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
    String[] styleIds = {"s0", "s1"};
    TtmlStyle style = new TtmlStyle();
    style.setBackgroundColor(Color.YELLOW);

    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(style, styleIds, globalStyles);
    assertThat(resolved).isSameAs(style);

    // inline attribute not overridden
    assertThat(resolved.getBackgroundColor()).isEqualTo(YELLOW);
    // inherited from both referential style
    assertThat(resolved.getStyle()).isEqualTo(STYLE_BOLD_ITALIC);
  }

  @Test
  public void testResolveStyleOnlyInlineStyle() {
    TtmlStyle inlineStyle = new TtmlStyle();
    assertThat(TtmlRenderUtil.resolveStyle(inlineStyle, null, null)).isSameAs(inlineStyle);
  }

  private static Map<String, TtmlStyle> getGlobalStyles() {
    Map<String, TtmlStyle> globalStyles = new HashMap<>();

    TtmlStyle s0 = new TtmlStyle();
    s0.setId("s0");
    s0.setBackgroundColor(Color.BLACK);
    s0.setBold(true);
    globalStyles.put(s0.getId(), s0);

    TtmlStyle s1 = new TtmlStyle();
    s1.setId("s1");
    s1.setBackgroundColor(Color.RED);
    s1.setFontColor(Color.RED);
    s1.setItalic(true);
    globalStyles.put(s1.getId(), s1);

    return globalStyles;
  }

}