https://github.com/andrewrunner/tdd-jest-practice

My experiments with jest test library (use pure http server on node.js)
https://github.com/andrewrunner/tdd-jest-practice

jest nodejs tdd typescript

Last synced: about 1 month ago
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My experiments with jest test library (use pure http server on node.js)

• Host: GitHub
• URL: https://github.com/andrewrunner/tdd-jest-practice
• Owner: andrewrunner
• Created: 2023-12-02T16:58:03.000Z (about 1 year ago)
• Default Branch: main
• Last Pushed: 2024-02-05T10:22:39.000Z (about 1 year ago)
• Last Synced: 2024-11-10T20:08:25.666Z (3 months ago)
• Topics: jest, nodejs, tdd, typescript
• Language: TypeScript
• Homepage:
• Size: 256 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# ex-jest-first-steps

My experiments with Jest test library

1. AAA principles (ARRANGE-ACT-ASSERT)

2. F.I.R.S.T. principles (Fast, Independent, Repitable, Self-validating, Thorough) 

Use 

- VSCode "REST Client" extension for run  .http files 

- https://github.com/microsoft/vscode-recipes/tree/main/debugging-jest-tests

Jest hooks can help init common mocks for all tests;

Principles:

- One class = one test case.

- One method = one or more tests.

- One alternative branch (if/switch/try-catch/exception) = one test.

Doubles:

- Dummy object

- Fakes

- Stubs

- Spiec

- Mocks 

Heavy mock testing approach

Advantages:

- Test classes in isolation

- Impose a strict coding style  (If class has too many dependencies - it makes it hard to test...)

- Once tests are in place, it easy to create new tests 

Disadvantages:

- Test and implementation are tighly coupled (small change leads to many changes)

- Hard to write 

Mike Cohn's pyramid tests consist of three levels (from bottom to top):

- Unit tests.

- Service tests.

- User interface tests.

In this pyramid, the main rule consists of two principles:

The higher the level, the fewer tests.