React Testing without Jest

Keeping things simple and lean

Usage

Creating Snapshots

• npm run test:snapshot to generate new snapshots!

Testing

• npm run test for a regular test
• npm run test:watch watch your project for changes to test files and the program files that they cover

Coverage

• npm run test:100 for a test with code coverage
• npm run test:report to see the open coverage report in a browser window

Why not Jest?

There are various problems with Jest:

• Takes over Node.js globals! 🔥
• It runs tests in copied/hacked Node.js environment which introduces some issues (not patchable)
  stdout and stderr are output of out sync facebook/jest#6718
  • Some public Node.js API's are replaced with non standard alternatives -> facebook/jest#67256725
  • Due to non standard and uneven modules cache handling it's prone to OOM errors: facebook/jest#6399 (comment)
• Tests progress is not output until tests finalize, which is inconvenient in long going tests (as integration ones) -> facebook/jest#6616 (not easily patchable)
• Any stdout/stderr output is hidden until test finalizes -> [facebook/jest#5281 (patchable with useStderr option)](https://github.com/facebook/jest#5281 (patchable with useStderr/issues/)option)
• Default runner exposes various bugs (patchable via using alternative jest-circus runner)
  • Crashes in beforeAll do not prevent execution of tests -> facebook/jest#2713, facebook/jest#6695
  • Crashes in afterAll are not exposed -> facebook/jest#66926692
  • only and skip are not fully respected -> facebook/jest#41664166
• Source code is result of transpilation which makes it more difficult to debug eventual issues