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Validating Shell Sort Algorithm Implementation in javascript-algorithms

This test suite validates the implementation of Shell Sort algorithm, focusing on sorting functionality, performance characteristics, and time complexity across different array scenarios. The tests verify both basic sorting capabilities and specific edge cases.

Test Coverage Overview

The test suite provides comprehensive coverage of Shell Sort implementation:

Basic array sorting validation
Custom comparator functionality testing
Negative numbers handling
Time complexity verification for different array types (equal, sorted, unsorted, reverse)

Implementation Analysis

The testing approach utilizes Jest’s describe/it pattern with a shared SortTester utility class. The implementation validates both functional correctness and algorithmic efficiency through visit count assertions for different array configurations.

Each test case focuses on specific aspects of the algorithm’s behavior, using predefined constants for complexity verification.

Technical Details

Testing Framework: Jest

SortTester utility for standardized sort testing
Complexity constants for performance validation
Array fixtures: equalArr, notSortedArr, reverseArr, sortedArr
Custom comparator support testing

Best Practices Demonstrated

The test suite exemplifies strong testing practices through modular test organization and comprehensive coverage. It employs consistent naming conventions, isolated test cases, and clear separation of concerns between test scenarios.

Standardized testing utilities
Performance benchmarking
Edge case coverage
Reusable test patterns

trekhleb/javascript-algorithms

src/algorithms/sorting/shell-sort/__test__/ShellSort.test.js

            
import ShellSort from '../ShellSort';
import {
  equalArr,
  notSortedArr,
  reverseArr,
  sortedArr,
  SortTester,
} from '../../SortTester';

// Complexity constants.
const SORTED_ARRAY_VISITING_COUNT = 320;
const NOT_SORTED_ARRAY_VISITING_COUNT = 320;
const REVERSE_SORTED_ARRAY_VISITING_COUNT = 320;
const EQUAL_ARRAY_VISITING_COUNT = 320;

describe('ShellSort', () => {
  it('should sort array', () => {
    SortTester.testSort(ShellSort);
  });

  it('should sort array with custom comparator', () => {
    SortTester.testSortWithCustomComparator(ShellSort);
  });

  it('should sort negative numbers', () => {
    SortTester.testNegativeNumbersSort(ShellSort);
  });

  it('should visit EQUAL array element specified number of times', () => {
    SortTester.testAlgorithmTimeComplexity(
      ShellSort,
      equalArr,
      EQUAL_ARRAY_VISITING_COUNT,
    );
  });

  it('should visit SORTED array element specified number of times', () => {
    SortTester.testAlgorithmTimeComplexity(
      ShellSort,
      sortedArr,
      SORTED_ARRAY_VISITING_COUNT,
    );
  });

  it('should visit NOT SORTED array element specified number of times', () => {
    SortTester.testAlgorithmTimeComplexity(
      ShellSort,
      notSortedArr,
      NOT_SORTED_ARRAY_VISITING_COUNT,
    );
  });

  it('should visit REVERSE SORTED array element specified number of times', () => {
    SortTester.testAlgorithmTimeComplexity(
      ShellSort,
      reverseArr,
      REVERSE_SORTED_ARRAY_VISITING_COUNT,
    );
  });
});