📚 Node.js Testing Guide

This project uses Node.js's built-in node:test module for writing and running unit tests, eliminating the need for external libraries like Jest. The test files are organized under the /test directory and executed using the node --test command.

🧪 Unit Testing

• Tests small pieces of code
• Runs in isolation (individual tests don't depend on each other)

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🔍 The AAA Pattern in Unit Testing

1️⃣ Arrange - Set up test data and conditions
2️⃣ Act - Execute the code being tested
3️⃣ Assert - Verify the results are as expected

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📦 Test Organization

1. Suits are for grouping related tests
2. describe is an alias for Suits

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🎭 Mocking

Simulates behavior of dependencies during testing. For example, if function A calls function B internally, we can mock function B.

For more detailed examples, check out order.test.js

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🧱 Stubs

Stubs provide ready-made data, similar to mocks, but without tracking call count and other behaviors that mocks provide.

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📸 Snapshot Testing — Mostly Used in Frontend

Especially useful for frontend testing when API responses return large JSON objects. Instead of manually asserting each key-pair, snapshots automatically compare the entire structure.

To update snapshots, run:

node --test --test-update-snapshots

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🔄 Integration Testing

Tests how different parts of the application work together.

Every API endpoint is tested using libraries like Jest.

Supertest is excellent for this type of testing.

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🌐 End-to-End Testing

Tests the entire application flow as a user would experience it:

• Open browser
• Fill in forms
• Check all interactions

Tools: Cypress, Playwright, Puppeteer

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📊 Testing Distribution (Industry Standard)

• E2E Testing: 10%
• Integration Testing: 20%
• Unit Testing: 70%

⚡ Performance Tip: Make sure tests run as fast as possible. Slow tests increase release time and can increase costs when running in CI/CD pipelines on services like EC2.

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🧠 TDD — Test-Driven Development

Reverses the typical development process:

1. Write tests for edge cases first
2. Implement the functionality to pass those tests

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Software Testing Types

1. Functional Testing

• Unit Testing
• Integration Testing
• System Testing
• User Acceptance Testing (UAT)
• Smoke Testing
• Sanity Testing
• Regression Testing
• Interface Testing

2. Non-Functional Testing

• Performance Testing
  • Load Testing
  • Stress Testing
  • Spike Testing
  • Endurance Testing
• Security Testing
• Usability Testing
• Compatibility Testing
• Reliability Testing
• Scalability Testing
• Accessibility Testing

3. Maintenance Testing

• Regression Testing
• Maintenance Testing

4. Other Testing Types

• Alpha Testing
• Beta Testing
• Ad-hoc Testing
• Exploratory Testing
• Black Box Testing
• White Box Testing
• Grey Box Testing
• Static Testing
• Dynamic Testing

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