---
description: Testing conventions (host-first, TDD for the pure core)
globs: **/test/**, **/tests/**, **/*Test*, **/*_test.*
alwaysApply: false
---

# Testing

Full spec: @AGENTS.md §8.

- Pure core is developed test-first (red -> green -> refactor):
  coefficient math, blob framing, config parsing, station-list logic —
  all host-tested, zero hardware.
- Arrange-Act-Assert; one behaviour per test; names state the behaviour
  (`tuneTo_rejectsFrequencyOutsideFmBand`).
- Fakes over mocks for driver interfaces; assert on observable behaviour,
  not internal call order.
- Hardware-in-the-loop tests are separate, explicitly marked, and never
  block the host suite.