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Testing Fisher-Yates Shuffle Algorithm Implementation in javascript-algorithms

This test suite validates the Fisher-Yates shuffle algorithm implementation in JavaScript. It ensures the algorithm correctly randomizes array elements while maintaining array integrity and original element preservation.

Test Coverage Overview

The test suite provides comprehensive coverage of the Fisher-Yates shuffle algorithm.

Tests empty and single-element array handling
Verifies random shuffling of larger arrays
Validates array length preservation
Confirms all original elements are retained

Implementation Analysis

The testing approach uses Jest’s describe/it blocks for structured test organization. It employs comparison testing to verify shuffle outcomes.

Uses expect assertions for array equality checks
Implements QuickSort for post-shuffle validation
Employs array length and content verification patterns

Technical Details

Testing Framework: Jest
Dependencies: QuickSort implementation
Test Utilities: SortTester for array comparison
Assertion Methods: toEqual, toBe, not.toEqual

Best Practices Demonstrated

The test suite exemplifies clean testing practices with clear test case separation and comprehensive edge case handling.

Edge case testing with empty and single-element arrays
Deterministic result validation using sorting
Clear test case descriptions
Modular test organization

trekhleb/javascript-algorithms

src/algorithms/sets/fisher-yates/__test__/fisherYates.test.js

            
import fisherYates from '../fisherYates';
import { sortedArr } from '../../../sorting/SortTester';
import QuickSort from '../../../sorting/quick-sort/QuickSort';

describe('fisherYates', () => {
  it('should shuffle small arrays', () => {
    expect(fisherYates([])).toEqual([]);
    expect(fisherYates([1])).toEqual([1]);
  });

  it('should shuffle array randomly', () => {
    const shuffledArray = fisherYates(sortedArr);
    const sorter = new QuickSort();

    expect(shuffledArray.length).toBe(sortedArr.length);
    expect(shuffledArray).not.toEqual(sortedArr);
    expect(sorter.sort(shuffledArray)).toEqual(sortedArr);
  });
});