Notes on Gary Bernhardt's "Boundaries" talk

README.md

Notes on Gary Bernhardt's "Boundaries" talk

https://www.destroyallsoftware.com/talks/boundaries

• test doubles
• test isolation example: Sweeper
  • win: enables test-driven design
  • win: outside-in tdd (top-down)
  • win: fast tests
  • lose: mocks and stubs may diverge from reality
• how can we fix the problems with isolated unit testing?
  • contract & collaboration tests
  • use tools (rspec-fire)
  • static typing / static mocks
  • use integration tests (don't isolate)
    • but integration tests are a scam
      • don't scale (too many paths)
      • superlinear test suite runtime
• values
  • pure functions are naturally isolated
  • let values be the boundaries
• paradigms
  • procedural
  • OOP
  • functional
  • fauxO
• functional core / imperative shell
  • core:
    • many paths
    • no dependencies
    • isolated
    • naturally suited to unit testing
  • shell
    • few paths
    • many dependencies
    • integrated
    • naturally suited to integration testing
• concurrency
  • actor model
    • processes with inboxes (queues)
    • the value is the boundary

terminology to follow up on:

• test doubles vs mocks vs stubs

let simple values be the boundaries between systems.