test-driven-development

Test-driven development applied pragmatically in the classical (Detroit) style: the iron law of a failing test first, red-green-refactor, testing behaviour rather than implementation (the unit is a behaviour or module, not a class), the test-double ladder that prefers real objects and in-memory implementations over stubs and mocks, state verification over interaction verification, keeping in-memory implementations faithful through contract tests, and the inner-loop scope of TDD, with TypeScript specifics. Composable with your own conventions.