Testing logic and interfaces

Automatically check that things are working as intended.


time section notes
00:00 Intro
00:39 Design Rich Hickey's Simple Made Easy talk
02:15 Part 1: logic
02:39 Add a function
09:12 Simple library OLSKHash
10:50 Complex library Zero Data Wrap
14:41 Part 2: interface
15:58 Add a link OLSKGazette
21:00 Access
21:42 Localize
22:39 Misc
23:48 Simple component OLSKPlaceholder
25:27 URLs for each test
27:14 Complex component OLSKAppToolbar
33:07 Messages
37:33 Concerns via files
38:36 General tips 'tests are your eyes'
42:27 Conclusion

Part 1: logic tests (AKA unit tests)

Requires no build system and ideally runs unlimited tests in about one second. See Modular object structure for syntax.

Part 2: interface tests (AKA UI/integration tests)

Requires a server for [[System A]] and also building process for [[System B]]. See Build and run my apps on your machine for setup. Takes more time than logic tests and gets longer with more tests: optimizations welcome. Look for localizing in another video [[localizing (tba)]].

Technical note: runs Zombie headless, no concept of CSS or box model, just HTML and JavaScript.


  • is it on screen or not?
  • decouple visibility from other concerns


  • put the maximum on screen
  • run suite for each supported language
  • will fail or make noise about missing translations
  • decouple language from other concerns


  • can be for checking attributes, binding, sending messages, anything
  • decouple configuration/behaviour from other concerns

General tips

  1. Test as much as you can. If something is not testable because of the testing environment, write the test that should pass and then skip it. I avoid changing anything before writing tests.

  2. 'Tests are your eyes' (via Zura) – they are imperfect and should be distrusted at some level, but ignoring them entirely is like 'playing jenga with blackboxes'. Let the machine work for you.

  3. Design for change. Assume that you have missed something and will need to adjust later. How easily can it be changed?

Part of Project workflow.

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