Rust Testing

This walks you through the full TDD cycle in Rust, from unit tests with assert macros to integration tests, async testing with Tokio, and property-based testing with proptest. It covers mocking with mockall, parameterized tests using rstest, and organizing test modules properly. The RED-GREEN-REFACTOR examples are practical, showing you how to start with todo!() and build up working code. If you're moving from other languages or just want to stop guessing at Rust test patterns, the coverage tooling suggestions and concrete code samples make this immediately useful. It assumes you know basic Rust but need the testing ecosystem laid out clearly.

skills.sh installs: 7.4K
GitHub stars: 300.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add affaan-m/ecc --skill rust-testing --agent claude-code

Installs into .claude/skills of the current project.

Files

Rust Testing Patterns

Comprehensive Rust testing patterns for writing reliable, maintainable tests following TDD methodology.

When to Use

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

How It Works

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%+

TDD Workflow for Rust

The RED-GREEN-REFACTOR Cycle

RED     → Write a failing test first
GREEN   → Write minimal code to pass the test
REFACTOR → Improve code while keeping tests green
REPEAT  → Continue with next requirement