Rust Write Tests

This is Rust testing discipline codified. It walks you through the "What Could Break?" framework (invariants, edge cases, platform differences, refactor risks) before you write a single assertion, then shows five concrete transformations from weak tests to robust ones: whole-object comparisons instead of is_ok checks, sibling test files instead of inline modules, typed fixtures instead of JSON strings. The flake hunting protocol is pulled from 97+ real commits and teaches event-driven sync over sleeps. Test names follow the subject-scenario-outcome pattern so failures read like bug reports. If you're writing Rust tests that actually catch regressions instead of just proving the happy path works, this gives you the checklist and the refactoring patterns to get there.