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Testing Snippet Recommendation Logic in 30-seconds-of-code

This test suite validates the RecommendationPresenter class functionality in the 30-seconds-of-code repository, focusing on snippet recommendation logic and filtering capabilities. The tests ensure proper handling of snippet recommendations based on language, tags, and listing status.

Test Coverage Overview

The test suite provides comprehensive coverage of the RecommendationPresenter’s recommendation system.

Key areas tested include:

Filtering out current snippets from recommendations
Handling cross-language snippet exclusion
Unlisted snippet filtering
Tag-based recommendation matching
Language-specific snippet filtering

Implementation Analysis

The testing approach utilizes Jest’s describe/it blocks for clear test organization and factory patterns for test data setup.

Notable implementation features:

Factory pattern for snippet creation
Modular test structure using describe blocks
Expectation chaining for precise assertions
Mock snippet data with varied attributes

Technical Details

Testing infrastructure includes:

Jest testing framework
Vitest for test execution
Custom Loader utility for module management
Factory classes for test data generation
ESLint configuration for code quality

Best Practices Demonstrated

The test suite exemplifies high-quality testing practices through clear organization and thorough coverage.

Notable practices include:

Descriptive test case naming
Isolated test scenarios
Comprehensive edge case handling
Consistent test data setup
Clear assertion patterns

chalarangelo/30-seconds-of-code

spec/presenters/recommendationPresenter.test.js

            
/* eslint-disable no-unused-vars */
import { describe, it, expect } from 'vitest';
import Loader from '#src/lib/loader.js';
import RecommendationPresenter from '#src/presenters/recommendationPresenter.js';

describe('RecommendationPresenter', () => {
  Loader.loadModules();
  const { CollectionFactory, SnippetFactory, CollectionSnippetFactory } =
    Loader.buildFactories();

  const snippet = SnippetFactory.create({
    languageId: 'javascript',
    id: 'js/s/my-snippet',
    shortTitle: 'My snippet',
    tags: 'array;object',
  });

  const sameSnippetOtherLanguage = SnippetFactory.create({
    languageId: 'python',
    id: 'py/s/my-snippet',
    shortTitle: 'My snippet',
    tags: 'array;object',
  });

  const unlistedSnippet = SnippetFactory.create('unlisted', {
    languageId: 'javascript',
    id: 'js/s/unrecommendable-snippet',
    shortTitle: 'Unrecommendable snippet',
    tags: 'array;object',
  });

  const highlyRecommendableSnippet = SnippetFactory.create({
    languageId: 'javascript',
    id: 'js/s/highly-recommendable-snippet',
    shortTitle: 'Highly recommendable snippet',
    tags: 'array;object',
  });

  const somewhatRecommendableSnippet = SnippetFactory.create({
    languageId: 'javascript',
    id: 'js/s/somewhat-recommendable-snippet',
    shortTitle: 'Somewhat recommendable snippet',
    tags: 'browser',
  });

  const presenter = new RecommendationPresenter(snippet);

  describe('#recommend_snippets', () => {
    const subject = presenter.recommendSnippets();

    it('returns snippets that are not the current snippet', () => {
      expect(subject).not.toContainEqual(snippet);
    });

    it('does not return the same snippet in another language', () => {
      expect(subject).not.toContainEqual(sameSnippetOtherLanguage);
    });

    it('does not return unlisted snippets', () => {
      expect(subject).not.toContainEqual(unlistedSnippet);
    });

    it('returns snippets in the same language with the same tags', () => {
      expect(subject).toContainEqual(highlyRecommendableSnippet);
    });

    it('returns snippets in the same language with similar tags', () => {
      expect(subject).toContainEqual(somewhatRecommendableSnippet);
    });
  });
});