Node.js: Testing and Code Quality

Learn how to measure quality, implement testing, and ensure code coverage in your node.js apps.

Introduction

• Cleaning your codebase
• What you should know
• Preparing for Node.js development
• Exercise files
• Demo setup and tour

1. Testing and Code Quality Fundamentals

• What is code quality?
• Coding conventions and standards
• Creating and enforcing coding standards
• Unit, integration, and functional testing
• Testing frameworks
• TDD and BDD test specifications
• Assertions for correctness
• Challenge: Organize your tests
• Solution: Organize your tests

2. Finding Errors with Linting

• Standardizing with EditorConfig
• Adding EditorConfig to a project and IDE
• Comparing JavaScript linters
• Installing ESLint
• Configuring ESLint
• Extending an ESLint shareable config
• Linting your codebase
• Fixing code in VSC with ESLint
• Challenge: Create a shareable ESLint config
• Solution: Create a shareable ESLint config

3. Validate Correctness with Unit Testing

• Survey of Node.js testing frameworks
• Install Jest in a Node.js project
• What and where to unit test?
• Writing your first Jest unit test
• Running a test suite with Jest
• Testing asynchronous callbacks with Jest
• Writing callback test suites with Jest
• Testing promises with Jest
• Challenge: Test async/await with Jest
• Solution: Test async/await with Jest

4. Replacing and Inspecting Using Spies, Stubs, and Mocks

• Replacing code with test doubles
• Mocking functions for test code
• Writing your first Jest mock
• Mock an entire module with Jest
• Mocking module dependencies
• Spying to observe interactions
• Challenge: Mock a successful reservation creation
• Solution: Mock a successful reservation creation

5. Reporting on Your Entire Codebase

• Why code coverage matters
• Measuring code coverage with Jest
• Functional testing with Jest
• Test doubles and Express apps
• Form submissions with SuperTest
• Fallacies of 100% test coverage
• Coverage with continuous integration
• Challenge: Isolate routes for faster tests
• Solution: Isolate routes for faster tests

Conclusion

• Testing and code quality goals
• Where to go from here?