Codex-RS Contributors Rust Testing Best Practices

A comprehensive guide to writing high-quality Rust tests at the standard established by the top codex-rs contributors. This skill encodes patterns for test architecture, assertions, mock servers, test data, event-driven testing, determinism, snapshot testing, and integration test infrastructure.

When to Apply

• Writing new tests for any Rust module in codex-rs
• Adding regression tests for a bug fix (3-6 tests per PR)
• Creating integration tests that interact with the Responses API via SSE mocks
• Modifying TUI rendering code that requires snapshot coverage
• Reviewing test code for adherence to codebase conventions

Rule Categories by Priority