Why test?

Reduce bugs

• You care about quality
• You want to reduce the amount of bugs now and going forward
• Defend from other programmers - they think different from you
• Regression tests
  • Ensure that the first time a human encounters a bug is the last time a human will

Refactoring

• You want to make refactoring easier
• Tests verify that things work
• Large changes become less "scary" because you can verify that things still work like they used to

Save time

• Saves time in the long run
• Less bugs = less time used in total
• Writing tests helps you think about edge cases
• If you've gotten the hang of it, writing tests is fast

It's fun!

• Seriously.
• Testing in JavaScript has come a long way
• Developer Experience has become first class
• Used to be really hard
• Higher level of abstraction today
• Has become much easier
• Having good test coverage just feels good

What do you mean with "UI testing"?

Unit test

• Test small units in isolation
• Runs very fast
• Don't test "the big picture"
• Tests methods' return values, functions' inputs, etc.

Integration tests

• Tests several units in combination
• Run somewhat slower
• Break more often due to more moving parts

UI tests

• Tests the entire app in a real browser
• Requires launching a browser
• Slower
• Can be brittle
• Tests actual use cases
• Gives great confidence that things work

What about Selenium?

Some history

• We have Selenium tests
• A student wrote them part-time
• Run in CI after a build is done
• Written in Java
• Uses cucumber
  • (Given X, then Y)
• AFM and HB have them
• Have largely been abandoned
  • No green build in 1+ year

Why it didn't work

• Front-end developers don't write Java
• Not enough handover
• Hard to debug when tests break
• Cucumber was the wrong approach; BDD is too far when we can't even to TDD
• Feedback was too slow
• Culture - we don't appreciate quality!

Introducing

Cypress.io

Cypress

• Integrates several tools together in one package
• Awesome DX
  • Watch mode
• Written with today's apps in mind
• Built to be debuggable
  • Time travel
• Stub network traffic
• Record videos of entire runs, and screenshots of failures