claudegoodies
Skill

rtk-tdd

From rtk-ai

>

Facts

Repository
rtk-ai/rtk
Status
Actively maintained
Last commit
Declared tools
Source file
.claude/skills/rtk-tdd/SKILL.md

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The instructions Claude Code reads when this skill runs.

# Rust TDD Workflow

## Three Laws of TDD

1. Do NOT write production code without a failing test
2. Write only enough test to fail (including compilation failure)
3. Write only enough production code to pass the failing test

Cycle: **RED** (test fails) -> **GREEN** (minimum to pass) -> **REFACTOR** (cleanup, cargo test)

## Red-Green-Refactor Steps

```
1. Write test in #[cfg(test)] mod tests of the SAME file
2. cargo test MODULE::tests::test_name  -- must FAIL (red)
3. Implement the minimum in the function
4. cargo test MODULE::tests::test_name  -- must PASS (green)
5. Refactor if needed, re-run cargo test (still green)
6. cargo fmt && cargo clippy --all-targets && cargo test  (final gate)
```

Never skip step 2. If the test passes immediately, it tests nothing.

## Idiomatic Rust Test Patterns

| Pattern | Usage | When |
|---------|-------|------|
| Arrange-Act-Assert | Base structure for every test | Always |
| `assert_eq!` / `assert!` | Direct comparison / booleans | Deterministic values |
| `assert!(result.is_err())` | Error path testing | Invalid inputs |
| `Result<()>` return type | Tests with `?` operator | Fallible functions |
| `#[should_panic]` | Expected panic | Invariants, preconditions |
| `tempfile::NamedTempFile` | File/I/O tests | Filesystem-dependent code |

## Patterns by Code Type

| Code Type | Test Pattern | Example |
|-----------|-------------|---------
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