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Validating TrackSelector Component Initialization in SmartTube

This test suite validates the core functionality of the TrackSelector component in ExoPlayer, focusing on bandwidth meter initialization and track selection behavior. The tests ensure proper handling of bandwidth measurement and selector state management.

Test Coverage Overview

The test suite provides coverage for TrackSelector initialization and bandwidth meter functionality. Key test cases include:

Verification of bandwidth meter access before initialization
Validation of bandwidth meter retrieval after proper initialization
Error handling for uninitialized state

Implementation Analysis

The testing approach utilizes JUnit and AndroidJUnit4 runner for Android-specific test execution. The implementation employs Mockito for mocking dependencies like BandwidthMeter and InvalidationListener, following a clear arrange-act-assert pattern.

Tests are structured around a base TrackSelector implementation with minimal required method overrides.

Technical Details

Testing tools and configuration:

JUnit framework with AndroidJUnit4 runner
Mockito mocking framework
Truth assertion library for fluent assertions
Custom TrackSelector implementation for testing

Best Practices Demonstrated

The test suite demonstrates several testing best practices:

Proper test initialization using @Before setup
Clear separation of test cases
Effective use of mocking for dependencies
Exception testing patterns
Focused test methods with clear naming conventions

yuliskov/smarttube

exoplayer-amzn-2.10.6/library/core/src/test/java/com/google/android/exoplayer2/trackselection/TrackSelectorTest.java

            
/*
 * Copyright (C) 2018 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.trackselection;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;

import androidx.test.ext.junit.runners.AndroidJUnit4;
import com.google.android.exoplayer2.ExoPlaybackException;
import com.google.android.exoplayer2.RendererCapabilities;
import com.google.android.exoplayer2.Timeline;
import com.google.android.exoplayer2.source.MediaSource.MediaPeriodId;
import com.google.android.exoplayer2.source.TrackGroupArray;
import com.google.android.exoplayer2.trackselection.TrackSelector.InvalidationListener;
import com.google.android.exoplayer2.upstream.BandwidthMeter;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;

/** Unit test for {@link TrackSelector}. */
@RunWith(AndroidJUnit4.class)
public class TrackSelectorTest {

  private TrackSelector trackSelector;

  @Before
  public void setUp() {
    trackSelector =
        new TrackSelector() {
          @Override
          public TrackSelectorResult selectTracks(
              RendererCapabilities[] rendererCapabilities,
              TrackGroupArray trackGroups,
              MediaPeriodId periodId,
              Timeline timeline)
              throws ExoPlaybackException {
            throw new UnsupportedOperationException();
          }

          @Override
          public void onSelectionActivated(Object info) {}
        };
  }

  @Test
  public void getBandwidthMeter_beforeInitialization_throwsException() {
    try {
      trackSelector.getBandwidthMeter();
      fail();
    } catch (Exception e) {
      // Expected.
    }
  }

  @Test
  public void getBandwidthMeter_afterInitialization_returnsProvidedBandwidthMeter() {
    InvalidationListener invalidationListener = Mockito.mock(InvalidationListener.class);
    BandwidthMeter bandwidthMeter = Mockito.mock(BandwidthMeter.class);
    trackSelector.init(invalidationListener, bandwidthMeter);

    assertThat(trackSelector.getBandwidthMeter()).isEqualTo(bandwidthMeter);
  }
}