testing-patterns

Place inline #[cfg(test)] mod tests modules at the bottom of each source file and run them with cargo test --lib. For async code use #[tokio::test], and filter tests by name substring or skip slow ones with -- --skip flags.

Prefer vi.fn() with dependency injection through function parameters over vi.mock() module mocks. Use vi.spyOn for existing methods, vi.stubEnv for environment variables, and always restore fake timers in afterEach to prevent cross-test leaks.

This skill uses the modern Swift Testing framework with @Test macros, @Suite structs, and #expect assertions rather than XCTest. Use @Suite(.serialized) for shared state and @MainActor for UI-bound ViewModel tests.

Run go test -race -cover ./... in your GitHub Actions workflow to catch data races and measure coverage. Test files use the *_test.go naming convention in the same package as the code under test for internal access.

Use property-based testing when a function has expressible invariants like round-trip, commutativity, or idempotency, especially for parsers, codecs, and serialization. Libraries include fast-check for TypeScript, proptest for Rust, and testing/quick for Go.

Skip testing framework internals, third-party API responses, trivial getters and delegation wrappers, and generated code. Focus coverage on boundary logic, parsing, serialization, crypto, state machines, and error paths.