Specification
- Skill ID
- rtk-ai/rtk/rtk-tdd
- Publisher
- rtk-ai
- Repository
- rtk
- Installs
- 0
- Files
- 2
- Synced
- Sep 23, 2026
How to use it
Open any RiverX project, open the Skills panel in the chat, and search for this identifier. The files are fetched from the source repository at install time.
rtk-ai/rtk/rtk-tddInstalls these files- SKILL.md
- references/testing-patterns.md
What this skill tells the agent
Rust TDD Workflow
Three Laws of TDD
- Do NOT write production code without a failing test
- Write only enough test to fail (including compilation failure)
- 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 |
|---|---|---|
| Pure function (str -> str) | Input literal -> assert output | assert_eq!(truncate("hello", 3), "...") |
| Parsing/filtering | Raw string -> filter -> contains/not-contains | assert!(filter(raw).contains("expected")) |
| Validation/security | Boundary inputs -> assert bool | assert!(!is_valid("../etc/passwd")) |
| Error handling | Bad input -> is_err() | assert!(parse("garbage").is_err()) |
| Struct/enum roundtrip | Construct -> serialize -> deserialize -> eq | assert_eq!(from_str(to_str(x)), x) |
Naming Convention
test_{function}_{scenario}
test_{function}_{input_type}Examples: test_truncate_edge_case, test_parse_invalid_input, test_filter_empty_string
When NOT to Use Pure TDD
- Functions calling
Command::new()-> test the parser, not the execution std::process::exit()-> refactor toResultfirst, then test the Result- Direct I/O (SQLite, network) -> use tempfile/mock or test the pure logic separately
- Main/CLI wiring -> covered by integration/smoke tests
Pre-Commit Gate
cargo fmt --all --check
cargo clippy --all-targets
cargo testAll 3 must pass. No exceptions. No #[allow(...)] without documented justification.
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