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Validating NAL Unit Bit Array Processing in SmartTube

This test suite validates the ParsableNalUnitBitArray class functionality in ExoPlayer, focusing on NAL unit bit parsing and handling escape sequences. The tests verify correct bit-level operations and Exp-Golomb code processing for video stream parsing.

Test Coverage Overview

The test suite provides comprehensive coverage of NAL unit bit array parsing operations, including:

Basic bit reading without escape sequences
Handling of escape sequences (0x000003)
Mixed content parsing scenarios
Exp-Golomb coded number reading
Edge cases including truncated data and buffer boundaries

Implementation Analysis

The testing approach uses JUnit with AndroidJUnit4 runner for Android-specific testing context. Tests are structured to verify both successful operations and error conditions, employing precise byte array inputs to test specific parsing scenarios.

Key patterns include data setup using TestUtil.createByteArray() and Truth assertions for verification.

Technical Details

Testing tools and configuration:

JUnit 4 testing framework
AndroidJUnit4 test runner
Google Truth assertion library
Custom test utilities for byte array creation
Structured test data arrays for different escape sequence scenarios

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Comprehensive edge case coverage
Clear test method naming conventions
Isolated test scenarios with specific test data
Proper error condition testing
Efficient test data setup and reuse

yuliskov/smarttube

exoplayer-amzn-2.10.6/library/core/src/test/java/com/google/android/exoplayer2/util/ParsableNalUnitBitArrayTest.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.util;

import static com.google.android.exoplayer2.testutil.TestUtil.createByteArray;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import androidx.test.ext.junit.runners.AndroidJUnit4;
import org.junit.Test;
import org.junit.runner.RunWith;

/** Tests for {@link ParsableNalUnitBitArray}. */
@RunWith(AndroidJUnit4.class)
public final class ParsableNalUnitBitArrayTest {

  private static final byte[] NO_ESCAPING_TEST_DATA = createByteArray(0, 3, 0, 1, 3, 0, 0);
  private static final byte[] ALL_ESCAPING_TEST_DATA = createByteArray(0, 0, 3, 0, 0, 3, 0, 0, 3);
  private static final byte[] MIX_TEST_DATA = createByteArray(255, 0, 0, 3, 255, 0, 0, 127);

  @Test
  public void testReadNoEscaping() {
    ParsableNalUnitBitArray array =
        new ParsableNalUnitBitArray(NO_ESCAPING_TEST_DATA, 0, NO_ESCAPING_TEST_DATA.length);
    assertThat(array.readBits(24)).isEqualTo(0x000300);
    assertThat(array.readBits(7)).isEqualTo(0);
    assertThat(array.readBit()).isTrue();
    assertThat(array.readBits(24)).isEqualTo(0x030000);
    assertThat(array.canReadBits(1)).isFalse();
    assertThat(array.canReadBits(8)).isFalse();
  }

  @Test
  public void testReadNoEscapingTruncated() {
    ParsableNalUnitBitArray array = new ParsableNalUnitBitArray(NO_ESCAPING_TEST_DATA, 0, 4);
    assertThat(array.canReadBits(32)).isTrue();
    array.skipBits(32);
    assertThat(array.canReadBits(1)).isFalse();
    try {
      array.readBit();
      fail();
    } catch (Exception e) {
      // Expected.
    }
  }

  @Test
  public void testReadAllEscaping() {
    ParsableNalUnitBitArray array =
        new ParsableNalUnitBitArray(ALL_ESCAPING_TEST_DATA, 0, ALL_ESCAPING_TEST_DATA.length);
    assertThat(array.canReadBits(48)).isTrue();
    assertThat(array.canReadBits(49)).isFalse();
    assertThat(array.readBits(15)).isEqualTo(0);
    assertThat(array.readBit()).isFalse();
    assertThat(array.readBits(17)).isEqualTo(0);
    assertThat(array.readBits(15)).isEqualTo(0);
  }

  @Test
  public void testReadMix() {
    ParsableNalUnitBitArray array =
        new ParsableNalUnitBitArray(MIX_TEST_DATA, 0, MIX_TEST_DATA.length);
    assertThat(array.canReadBits(56)).isTrue();
    assertThat(array.canReadBits(57)).isFalse();
    assertThat(array.readBits(7)).isEqualTo(127);
    assertThat(array.readBits(2)).isEqualTo(2);
    assertThat(array.readBits(17)).isEqualTo(3);
    assertThat(array.readBits(7)).isEqualTo(126);
    assertThat(array.readBits(23)).isEqualTo(127);
    assertThat(array.canReadBits(1)).isFalse();
  }

  @Test
  public void testReadExpGolomb() {
    ParsableNalUnitBitArray array = new ParsableNalUnitBitArray(createByteArray(0x9E), 0, 1);
    assertThat(array.canReadExpGolombCodedNum()).isTrue();
    assertThat(array.readUnsignedExpGolombCodedInt()).isEqualTo(0);
    assertThat(array.readUnsignedExpGolombCodedInt()).isEqualTo(6);
    assertThat(array.readUnsignedExpGolombCodedInt()).isEqualTo(0);
    assertThat(array.canReadExpGolombCodedNum()).isFalse();
    try {
      array.readUnsignedExpGolombCodedInt();
      fail();
    } catch (Exception e) {
      // Expected.
    }
  }

  @Test
  public void testReadExpGolombWithEscaping() {
    ParsableNalUnitBitArray array =
        new ParsableNalUnitBitArray(createByteArray(0, 0, 3, 128, 0), 0, 5);
    assertThat(array.canReadExpGolombCodedNum()).isFalse();
    array.skipBit();
    assertThat(array.canReadExpGolombCodedNum()).isTrue();
    assertThat(array.readUnsignedExpGolombCodedInt()).isEqualTo(32767);
    assertThat(array.canReadBits(1)).isFalse();
  }

  @Test
  public void testReset() {
    ParsableNalUnitBitArray array = new ParsableNalUnitBitArray(createByteArray(0, 0), 0, 2);
    assertThat(array.canReadExpGolombCodedNum()).isFalse();
    assertThat(array.canReadBits(16)).isTrue();
    assertThat(array.canReadBits(17)).isFalse();
    array.reset(createByteArray(0, 0, 3, 0), 0, 4);
    assertThat(array.canReadBits(24)).isTrue();
    assertThat(array.canReadBits(25)).isFalse();
  }

}