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Testing Binary Bit Counting Implementation in javascript-algorithms

This test suite validates the countSetBits function, which calculates the number of set bits (1s) in binary representations of integers. The tests cover both positive and negative numbers, verifying accurate bit counting across different numerical ranges.

Test Coverage Overview

The test suite provides comprehensive coverage for the countSetBits function, examining various integer inputs.

Key test cases include:

Zero and single-bit numbers (0, 1)
Small positive integers (2-21)
Larger positive numbers (255, 1023)
Negative integers (-1, -21, -255, -1023)
Edge case with large negative number (-4294967296)

Implementation Analysis

The testing approach utilizes Jest’s describe/it pattern for structured test organization. Each test case employs the expect().toBe() assertion to verify exact matches between actual and expected bit counts.

The implementation demonstrates systematic testing of binary operations, using a range of numbers to validate the algorithm’s accuracy across different bit patterns and integer ranges.

Technical Details

Testing Infrastructure:

Framework: Jest
Test Type: Unit Test
File Structure: Modular test file with single test suite
Import Pattern: Direct module import
Assertion Style: Equality matching with toBe()

Best Practices Demonstrated

The test suite exhibits several testing best practices for bit manipulation algorithms.

Notable practices include:

Comprehensive edge case coverage
Clear test case organization
Systematic input value progression
Boundary value testing
Negative number handling

trekhleb/javascript-algorithms

src/algorithms/math/bits/__test__/countSetBits.test.js

            
import countSetBits from '../countSetBits';

describe('countSetBits', () => {
  it('should return number of set bits', () => {
    expect(countSetBits(0)).toBe(0);
    expect(countSetBits(1)).toBe(1);
    expect(countSetBits(2)).toBe(1);
    expect(countSetBits(3)).toBe(2);
    expect(countSetBits(4)).toBe(1);
    expect(countSetBits(5)).toBe(2);
    expect(countSetBits(21)).toBe(3);
    expect(countSetBits(255)).toBe(8);
    expect(countSetBits(1023)).toBe(10);
    expect(countSetBits(-1)).toBe(32);
    expect(countSetBits(-21)).toBe(30);
    expect(countSetBits(-255)).toBe(25);
    expect(countSetBits(-1023)).toBe(23);
    expect(countSetBits(-4294967296)).toBe(0);
  });
});