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Testing Object Hash Generation Consistency in Parcel Bundler

This test suite validates the objectHash utility in Parcel, ensuring consistent and unique hash generation for JavaScript objects. The tests verify hash consistency for deep equal objects while maintaining uniqueness for different object structures.

Test Coverage Overview

The test suite provides comprehensive coverage of the objectHash functionality, focusing on hash generation consistency and uniqueness.

Tests deep equality hash generation for nested objects
Verifies unique hash generation for different object structures
Covers edge cases with nested arrays and object properties
Validates hash consistency across multiple object instances

Implementation Analysis

The testing approach utilizes Jest’s describe/it pattern for organized test structure and assertion-based validation. The implementation leverages Node’s assert module for equality checking, demonstrating both positive and negative test cases for hash comparison.

Uses describe blocks for logical test grouping
Implements individual test cases with clear assertions
Employs direct comparison testing patterns

Technical Details

Testing Framework: Jest
Assertion Library: Node.js assert module
Flow type checking enabled
Test Environment: Node.js
File Organization: Modular test structure

Best Practices Demonstrated

The test suite exemplifies several testing best practices, including clear test case isolation and descriptive test naming. Each test focuses on a specific aspect of the hash generation functionality, with well-structured assertions and proper setup.

Isolated test cases
Descriptive test names
Clear assertion patterns
Comprehensive edge case coverage

parcel-bundler/parcel

packages/core/utils/test/objectHash.test.js

            
// @flow
import assert from 'assert';
import objectHash from '../src/objectHash';

describe('objectHash', () => {
  it('calculates the same hash for two different but deep equal objects', () => {
    const obj1 = {
      foo: {foo: 'foo', baz: ['foo', 'baz', 'bar'], bar: 'bar'},
      baz: 'baz',
      bar: 'bar',
    };
    const obj2 = {
      foo: {foo: 'foo', baz: ['foo', 'baz', 'bar'], bar: 'bar'},
      baz: 'baz',
      bar: 'bar',
    };

    assert.equal(objectHash(obj1), objectHash(obj2));
  });

  it('calculates a unique hash for two deep equal objects', () => {
    const obj1 = {
      baz: 'baz',
      bar: 'ba',
    };
    const obj2 = {
      baz: 'baz',
      bar: 'bar',
    };

    assert.notEqual(objectHash(obj1), objectHash(obj2));
  });
});