rust

name	rust
description	Rust development guidance. Covers project setup, testing, clippy, rustfmt, and CI/CD patterns. Use when creating, modifying, or debugging Rust code.

Rust Development Skill

Conventions for Rust development, with a dedicated section for Zellij WASM plugin development.

Core Conventions

• Rust stable toolchain (rustup default stable)
• Cargo for build, test, lint, format — no external build tools needed
• clippy for linting, rustfmt for formatting
• Edition 2021 minimum
• Workspace layout for multi-crate projects, single Cargo.toml otherwise

Project Scaffold

<project>/
├── Cargo.toml              # Package metadata, deps, lint config
├── rustfmt.toml            # max_width = 100
├── src/
│   ├── lib.rs              # Library root (or main.rs for binary)
│   └── ...
├── tests/
│   └── integration_test.rs
└── .github/workflows/ci.yml

Tooling Quick Reference

Clippy (Linting)

cargo clippy                        # Lint
cargo clippy -- -D warnings         # Warnings as errors (CI)
cargo clippy --all-targets           # Include tests/benches
cargo clippy --fix                   # Auto-fix

Project config in Cargo.toml:

[lints.clippy]
pedantic = { level = "warn", priority = -1 }
unwrap_used = "warn"

Rustfmt (Formatting)

cargo fmt                           # Format
cargo fmt -- --check                # Check only (CI)

Build & Test

cargo build                         # Debug build
cargo build --release               # Release build
cargo test                          # All tests
cargo test -- --nocapture            # Show println output
cargo test test_name                 # Specific test
cargo test --lib                     # Unit tests only
cargo test --test integration_test   # Specific integration test

Other Useful Commands

cargo doc --open                    # Generate and browse docs
cargo audit                         # Security vulnerability check
cargo tree                          # Dependency tree
cargo expand                        # Macro expansion

Testing Patterns

Unit Tests (in-module)

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_valid() {
        let result = parse("input");
        assert_eq!(result, expected);
    }
}

Async Tests (tokio)

#[tokio::test]
async fn test_async_op() {
    let result = fetch_data().await;
    assert!(result.is_ok());
}

Error Handling

Context	Pattern
Libraries	thiserror::Error derive for custom error types
Applications	anyhow::Result for ergonomic error propagation
Unwrap	Never in library code; expect("reason") in main/tests only

Common Dependencies

Crate	Purpose
serde + serde_json	Serialization
tokio	Async runtime
anyhow / thiserror	Error handling
clap	CLI parsing
tracing	Structured logging

CI/CD

name: CI
on: [push, pull_request]
jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
      - run: cargo fmt -- --check
      - run: cargo clippy -- -D warnings
      - run: cargo test