Code Testing

• User test: test that something provides user value
• Unit test: test that a unit of code (class, component, function) does what's required
• End-to-end test: test the system by interacting with the user interface
• Acceptance test: end-to-end test that represents a client's definition of when a user story is done
• Stress test: test that the app can scale (many users, ton of data, ...)

• Client and developers define acceptance tests for each user story
  • current iteration stories only!
• Typically a new product will eventually end up with dozens to a hundreds
• Automate with end-to-end testers, such as Cypress

• Written by developers
• Meant to test code units (functions, methods, classes)
• Should be numerous, fast, automated
• Automate with unit testing libraries like Vitest and Jest

• Test ability to handle many users, tons of data, hostile attacks, ...
• Automate with tools that simulate multiple simultaneous users, randomized data
  • e.g., Apache Bench, Apache JMeter, Gatling

• Start small
  • Write an ARE WE UP? test
  • Write acceptance tests for core demo paths
• Add tests for every bug that got deployed
• Do TDD when developing code with tricky or "must not fail" logic

• When a bug happens, don't fix it right away.
• Write a unit test that reliably reproduces the bug
  • If you can't, you don't know what the bug is
• Now write code to pass the test and fix the bug

• Why?
  • Running tests still takes time
  • Easy to forget to run them
• Solution: continuous integration server
  • A separate machine that runs all tests
  • Runs automatically on every commit to main

Thanks to Hakim El Hattab for RevealJS