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Testing Gradient Color Position Merging in Lottie Android

This test suite validates the AnimatableGradientColorValue class functionality in Lottie Android, focusing on position merging operations for gradient color animations. The tests ensure proper handling of gradient position arrays across different scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of gradient position merging logic with three distinct test cases:

Identical position array merging
Different position array concatenation
Overlapping position array handling

Each test verifies the accuracy of position calculations crucial for gradient animations.

Implementation Analysis

The testing approach utilizes JUnit’s assertion framework to validate float array operations. The implementation follows AAA (Arrange-Act-Assert) pattern with assertArrayEquals for precise floating-point comparisons, using a delta tolerance parameter for floating-point equality checks.

The tests systematically verify the mergePositions method behavior across different input scenarios.

Technical Details

Testing tools and configuration:

JUnit 4 testing framework
Static imports for assertion methods
Float array comparison with delta tolerance
Integration with Lottie Android animation system

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases with single responsibility
Clear test method naming reflecting test scenarios
Precise floating-point comparison handling
Comprehensive edge case coverage
Consistent assertion pattern usage

airbnb/lottie-android

lottie/src/test/java/com/airbnb/lottie/model/animatable/AnimatableGradientColorValueTest.java

            
package com.airbnb.lottie.model.animatable;

import static org.junit.Assert.*;

import org.junit.Test;

public class AnimatableGradientColorValueTest {
  @Test
  public void testMergeTheSame() {
    assertArrayEquals(new float[]{1, 2}, AnimatableGradientColorValue.mergePositions(new float[]{1, 2}, new float[]{1, 2}), 0f);
  }

  @Test
  public void testMergeDifferent() {
    assertArrayEquals(new float[]{1, 2, 3, 4}, AnimatableGradientColorValue.mergePositions(new float[]{1, 2}, new float[]{3, 4}), 0f);
  }

  @Test
  public void testMergeOneOverlap() {
    assertArrayEquals(new float[]{1, 2, 3}, AnimatableGradientColorValue.mergePositions(new float[]{1, 2}, new float[]{2, 3}), 0f);
  }
}