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Testing Recursive Longest Common Subsequence Implementation in javascript-algorithms

This test suite validates the recursive implementation of the Longest Common Subsequence (LCS) algorithm in JavaScript. The tests verify the algorithm’s ability to find the longest sequence of characters that appear in both input strings while maintaining their relative order.

Test Coverage Overview

The test suite provides comprehensive coverage for the LCS recursive implementation, testing various string combinations and edge cases.

Empty string handling for both inputs
Single-sided empty string scenarios
Short string comparisons with partial matches
Complex string matches with multiple common characters
Long sentence comparisons with full matches

Implementation Analysis

The testing approach utilizes Jest’s describe-it pattern for structured test organization. Each test case employs expect().toBe() assertions to validate exact string matching.

Uses Jest’s built-in assertion library
Implements multiple test cases in a single test block
Follows AAA (Arrange-Act-Assert) pattern implicitly

Technical Details

Testing Framework: Jest
Test Type: Unit Test
Import Strategy: ES6 module import
Assertion Style: Expect syntax
File Organization: Dedicated test directory (__test__)

Best Practices Demonstrated

The test suite exemplifies several testing best practices, including comprehensive edge case coverage and clear test case organization.

Boundary testing with empty strings
Progressive complexity in test cases
Clear and descriptive test descriptions
Consistent assertion pattern usage
Isolated test cases for specific scenarios

trekhleb/javascript-algorithms

src/algorithms/sets/longest-common-subsequence/__test__/longestCommonSubsequenceRecursive.test.js

            
import longestCommonSubsequence from '../longestCommonSubsequenceRecursive';

describe('longestCommonSubsequenceRecursive', () => {
  it('should find longest common substring between two strings', () => {
    expect(longestCommonSubsequence('', '')).toBe('');
    expect(longestCommonSubsequence('ABC', '')).toBe('');
    expect(longestCommonSubsequence('', 'ABC')).toBe('');
    expect(longestCommonSubsequence('ABABC', 'BABCA')).toBe('BABC');
    expect(longestCommonSubsequence('BABCA', 'ABCBA')).toBe('ABCA');
    expect(longestCommonSubsequence('sea', 'eat')).toBe('ea');
    expect(longestCommonSubsequence('algorithms', 'rithm')).toBe('rithm');
    expect(longestCommonSubsequence(
      'Algorithms and data structures implemented in JavaScript',
      'Here you may find Algorithms and data structures that are implemented in JavaScript',
    )).toBe('Algorithms and data structures implemented in JavaScript');
  });
});