rust-backend-testing

Use testcontainers to spin up isolated database instances for each test run. Testcontainers manages container lifecycle automatically, ensuring fresh state and cleanup without manual Docker commands, enabling reliable integration tests against real PostgreSQL, MySQL, or other databases alongside your Rust backend code.

Yes, use mockall to derive trait-based mocks for your service dependencies. Mockall generates mock implementations that verify function calls and return values you specify, isolating components for fast unit tests without containers or network calls.

Use axum-test to send requests directly to handlers without starting a server. It provides a synchronous testing client compatible with Axum's routing and middleware, letting you verify endpoint behavior, status codes, and response bodies in isolated unit tests.

Testcontainers creates a fresh container per test by default, ensuring complete isolation. Alternatively, wrap database operations in transactions that roll back after each test, preventing state leakage between parallel runs while reducing container overhead.

Yes. Use mockall for unit tests of business logic, testcontainers for integration tests verifying database interactions, and axum-test for HTTP handler tests. Multi-level coverage catches bugs at each layer—mocks verify contracts, integration tests verify data flow, and handler tests verify API behavior.

Yes, mockall generates mocks for traits, not concrete types. Design service layers with trait abstractions for external dependencies like database connections or API clients, then mock those traits in tests while swapping real implementations in production.