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Validating EmptySignature Object Equality in Glide Library

This test suite validates the EmptySignature class in the Glide image loading library, focusing on object equality and hash code consistency. It ensures that empty signatures behave predictably when used as cache keys in Glide’s image loading pipeline.

Test Coverage Overview

The test suite provides focused coverage of EmptySignature object behavior and equality comparison.

Tests object equality between EmptySignature instances
Verifies empty digest regression scenarios
Validates comparison with other Key implementations
Ensures consistent object instantiation via obtain() factory method

Implementation Analysis

The testing approach utilizes JUnit4 and custom KeyTester utility for thorough equality testing.

The implementation leverages equivalence group testing patterns to verify object equality, identity, and hash code consistency. The test employs Mockito for creating mock Key objects to validate differentiation between EmptySignature and other Key types.

Technical Details

Testing Framework: JUnit 4
Mocking Framework: Mockito
Custom Utilities: KeyTester for equality validation
Test Runner: JUnit4 Runner
Key Testing Features: Equivalence groups, digest regression testing

Best Practices Demonstrated

The test demonstrates excellent testing practices through focused scope and comprehensive validation.

Uses Rule annotation for test infrastructure setup
Implements equivalence group testing for thorough object comparison
Employs mock objects to test boundary conditions
Maintains single responsibility principle in test methods

bumptech/glide

library/test/src/test/java/com/bumptech/glide/signature/EmptySignatureTest.java

            
package com.bumptech.glide.signature;

import static org.mockito.Mockito.mock;

import com.bumptech.glide.load.Key;
import com.bumptech.glide.tests.KeyTester;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
public class EmptySignatureTest {
  @Rule public final KeyTester keyTester = new KeyTester();

  @Test
  public void testEquals() {
    keyTester
        .addEquivalenceGroup(EmptySignature.obtain(), EmptySignature.obtain())
        .addEquivalenceGroup(mock(Key.class))
        .addEmptyDigestRegressionTest(EmptySignature.obtain())
        .test();
  }
}