Rust Testing

High-signal guidance for Rust tests that are deterministic, maintainable, and worth running.

Use this skill when tests are part of the change, when flakiness needs to die quietly, or when CI needs stronger signal.

When to activate

• Adding unit, integration, async, or doctests for Rust code
• Refactoring brittle or slow Rust tests
• Introducing fakes, mocks, property tests, or snapshot tests
• Tightening CI feedback with coverage, nextest, or command selection
• Hardening parsers, unsafe, or FFI code against arbitrary input with fuzzing, Miri, or sanitizers
• Testing locks, atomics, or shutdown joins (Loom, Miri races, deadlock)

Core rules