Rust Testing Patterns
2026-04-16//
Rust Testing Patterns
Expert Rust projects employ layered testing and enforce quality through CI configuration that catches issues before they reach code review.
Testing layers
- Unit tests in
#[cfg(test)]modules test internal logic with full access to private functions - Integration tests in
tests/exercise only the public API, catching interface regressions - Doc tests in
///comments serve as both documentation and regression tests — the Rust API Guidelines mandate using?instead ofunwrap()to show callers the correct error-handling pattern - Property-based testing with proptest generates random inputs to verify invariants hold universally, catching edge cases hand-written tests miss. bolero unifies fuzzing and property testing under a single API.
CI lint enforcement
Production Rust CI pipelines run cargo clippy -- -D warnings with pedantic and selected restriction lints. Key restriction lints:
| Lint | Purpose |
|---|---|
clippy::unwrap_used |
Force explicit error handling |
clippy::expect_used |
Same, for expect calls |
clippy::needless_clone |
Catch unnecessary allocations |
clippy::ptr_arg |
Catch &Vec<T> where &[T] suffices |
Testing with both --all-features and --no-default-features catches feature-flag interaction bugs. cargo audit scans for known vulnerabilities. See cargo-deny for comprehensive dependency auditing.
Related pages
See expert-rust-design for the broader design philosophy, cargo-nextest for parallel test execution, and rust-workspace-patterns for workspace-level CI configuration.
Linked from
Sources
- Raw/Rust/What A+ Rust design actually looks like.md