davideisinger.com/content/notes/good-tests/index.md

title, date, draft

title	date	draft
Good Tests	2023-05-12T23:40:19-04:00	false

(Notes for a Viget article I'm putting together)

• Most importantly: give you confidence to make changes
• Focus on two kinds of tests: unit and integration
  • Unit: test your objects/functions directly
  • Integration: simulated browser interactions
  • If you're building an API, you might also have request specs
    • But ideally you're testing the full integration of UI + API
• Unit tests
  • Put complex logic into easily testable objects/functions
  • Avoid over-stubbing/mocking -- what are you even testing
• Integration tests
  • You need proper end-to-end testing
  • Set up your data (fresh per test)
  • Visit a page
  • Interact with it
  • Make assertions about the results
• Third-party/network calls
  • VCR is … OK but can become a maintenance problem
  • Block access to the web
  • Create stub objects to stand in for network calls
  • Use JSON Schema to ensure stub stays in sync
  • This will lead to more reliable tests and also more robust code
• Coverage
  • We shoot for 100% in SimpleCov (So all the Ruby is tested)
  • Some consider this too high or too burdensome -- I don't
  • If it's 100%, you instantly know if you have any untested code
    • If it's, say, 94%, and you add 100 lines, six of those can be untested -- hope they're perfect!
    • In other words, at less than 100% coverage, you don't know if your new feature is fully covered or not
  • Occasionally you have to ignore some code -- e.g. something that only runs in production
• Flaky tests are bad
  • They eat up a lot of development time (esp. as build times increase)
  • Try to stay on top of them and squash them as they arise
  • Some frameworks have retry options/libraries that can help (bandage not cure)
  • In general, though, flaky tests suck and generally indicate lack of quality with either your code or your tools

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