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Testing Peak-Valley Stock Trading Algorithm Implementation in javascript-algorithms

This test suite validates a peak-valley algorithm for determining optimal stock trading profits. It examines various price sequences to verify the algorithm correctly calculates maximum potential gains from buying and selling stocks at different time points.

Test Coverage Overview

The test suite provides comprehensive coverage of the peak-valley stock trading algorithm, examining both simple and complex price sequences.

Tests basic two-price scenarios
Validates single price edge cases
Examines ascending and descending sequences
Verifies complex price patterns with multiple peaks and valleys
Tests visit function call counts for performance tracking

Implementation Analysis

The testing approach uses Jest’s expect assertions and mock functions to verify both algorithm outputs and internal behavior.

Implements jest.fn() for visit tracking
Uses toEqual matcher for precise result validation
Employs toHaveBeenCalledTimes for execution count verification
Structured test cases progress from simple to complex scenarios

Technical Details

Testing Framework: Jest
Mock Functions: jest.fn()
Assertion Methods: expect, toEqual, toHaveBeenCalledTimes
Test Structure: describe/it blocks
Input Types: Array of numbers, optional visit callback

Best Practices Demonstrated

The test suite exemplifies several testing best practices for algorithm validation.

Progressive complexity in test cases
Edge case coverage
Performance monitoring through visit counting
Clear test case organization
Consistent assertion patterns

trekhleb/javascript-algorithms

src/algorithms/uncategorized/best-time-to-buy-sell-stocks/__tests__/peakvalleyBestTimeToBuySellStocks.test.js

            
import peakvalleyBestTimeToBuySellStocks from '../peakvalleyBestTimeToBuySellStocks';

describe('peakvalleyBestTimeToBuySellStocks', () => {
  it('should find the best time to buy and sell stocks', () => {
    let visit;

    expect(peakvalleyBestTimeToBuySellStocks([1, 5])).toEqual(4);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([1], visit)).toEqual(0);
    expect(visit).toHaveBeenCalledTimes(1);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([1, 5], visit)).toEqual(4);
    expect(visit).toHaveBeenCalledTimes(2);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([5, 1], visit)).toEqual(0);
    expect(visit).toHaveBeenCalledTimes(2);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([1, 5, 10], visit)).toEqual(9);
    expect(visit).toHaveBeenCalledTimes(3);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([10, 1, 5, 20, 15, 21], visit)).toEqual(25);
    expect(visit).toHaveBeenCalledTimes(6);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([7, 1, 5, 3, 6, 4], visit)).toEqual(7);
    expect(visit).toHaveBeenCalledTimes(6);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([1, 2, 3, 4, 5], visit)).toEqual(4);
    expect(visit).toHaveBeenCalledTimes(5);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks([7, 6, 4, 3, 1], visit)).toEqual(0);
    expect(visit).toHaveBeenCalledTimes(5);

    visit = jest.fn();
    expect(peakvalleyBestTimeToBuySellStocks(
      [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20],
      visit,
    )).toEqual(19);
    expect(visit).toHaveBeenCalledTimes(20);
  });
});