rust-testing

Comprehensive Rust testing patterns for writing reliable, maintainable tests following TDD methodology. DO: DON'T: Remember : Tests are documentation. They show how your code is meant to be used. Write them clearly and keep them up to date. - Writing new Rust functions, methods, or traits - Adding test coverage to existing code - Creating benchmarks for performance-critical code - Implementing property-based tests for input validation - Following TDD workflow in Rust projects - Identify target code — Find the function, trait, or module to test - Write a test — Use #[test] in a #[cfg(test)] module, rstest for parameterized tests, or proptest for property-based tests - Mock dependencies — Use mockall to isolate the unit under test - Run tests (RED) — Verify the test fails with the expected error - Implement (GREEN) — Write minimal code to pass - Refactor — Improve while keeping tests green - Check coverage — Use cargo-llvm-cov, target 80%+ - Write tests FIRST (TDD) - Use #[cfg(test)] modules for unit tests - Test behavior, not implementation - Use descriptive test names that explain the scenario - Prefer assert_eq! over assert! for better error messages - Use ? in tests that return Result for cleaner error output - Keep tests independent — no shared mutable state - Use #[should_panic] when you can test Result::is_err() instead - Mock everything — prefer integration tests when...