shell: fish functions -> ~/.local/bin executables + bash/zsh ports; manage ~/.agents

- 16 cross-shell utilities converted to sh/bash chezmoi executables: ai c2p cp-appid extract_agents fab gdc gh-sonr-org-migrate ghg-clone ghn gho git-summary launch_omp_livediff_overlay lc-elir mdcp mdp pj (ghg-clone not named ghg: unrelated cargo binary owns that name) - cwd/history helpers stay per-shell: yy c cd clip-last + ghg/ghn/gho cd-wrappers in bash/functions/ and zsh/functions/, loaded by rc files - fish keeps only shell-state functions; converted ones now hit PATH - cp-appid ignore gating moved to .local/bin path - dot_agents/skills: 82 skills materialized from dotstate storage so dot_claude skill symlinks resolve on fresh bootstrap; dotstate profile/symlinks.json released .agents/skills .bashrc .zshrc
2026-11-05 04:08:03 +00:00 · 2026-08-10 15:15:06 -04:00
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+---
+name: rust-testing
+description: Rust testing patterns including unit tests, integration tests, async testing, property-based testing, mocking, and coverage. Follows TDD methodology.
+metadata:
+  origin: ECC
+---
+
+# 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
+
+1. **Identify target code** — Find the function, trait, or module to test
+2. **Write a test** — Use `#[test]` in a `#[cfg(test)]` module, rstest for parameterized tests, or proptest for property-based tests
+3. **Mock dependencies** — Use mockall to isolate the unit under test
+4. **Run tests (RED)** — Verify the test fails with the expected error
+5. **Implement (GREEN)** — Write minimal code to pass
+6. **Refactor** — Improve while keeping tests green
+7. **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
+```
+
+### Step-by-Step TDD in Rust
+
+```rust
+// RED: Write test first, use todo!() as placeholder
+pub fn add(a: i32, b: i32) -> i32 { todo!() }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_add() { assert_eq!(add(2, 3), 5); }
+}
+// cargo test → panics at 'not yet implemented'
+```
+
+```rust
+// GREEN: Replace todo!() with minimal implementation
+pub fn add(a: i32, b: i32) -> i32 { a + b }
+// cargo test → PASS, then REFACTOR while keeping tests green
+```
+
+## Unit Tests
+
+### Module-Level Test Organization
+
+```rust
+// src/user.rs
+pub struct User {
+    pub name: String,
+    pub email: String,
+}
+
+impl User {
+    pub fn new(name: impl Into<String>, email: impl Into<String>) -> Result<Self, String> {
+        let email = email.into();
+        if !email.contains('@') {
+            return Err(format!("invalid email: {email}"));
+        }
+        Ok(Self { name: name.into(), email })
+    }
+
+    pub fn display_name(&self) -> &str {
+        &self.name
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn creates_user_with_valid_email() {
+        let user = User::new("Alice", "alice@example.com").unwrap();
+        assert_eq!(user.display_name(), "Alice");
+        assert_eq!(user.email, "alice@example.com");
+    }
+
+    #[test]
+    fn rejects_invalid_email() {
+        let result = User::new("Bob", "not-an-email");
+        assert!(result.is_err());
+        assert!(result.unwrap_err().contains("invalid email"));
+    }
+}
+```
+
+### Assertion Macros
+
+```rust
+assert_eq!(2 + 2, 4);                                    // Equality
+assert_ne!(2 + 2, 5);                                    // Inequality
+assert!(vec![1, 2, 3].contains(&2));                     // Boolean
+assert_eq!(value, 42, "expected 42 but got {value}");    // Custom message
+assert!((0.1_f64 + 0.2 - 0.3).abs() < f64::EPSILON);   // Float comparison
+```
+
+## Error and Panic Testing
+
+### Testing `Result` Returns
+
+```rust
+#[test]
+fn parse_returns_error_for_invalid_input() {
+    let result = parse_config("}{invalid");
+    assert!(result.is_err());
+
+    // Assert specific error variant
+    let err = result.unwrap_err();
+    assert!(matches!(err, ConfigError::ParseError(_)));
+}
+
+#[test]
+fn parse_succeeds_for_valid_input() -> Result<(), Box<dyn std::error::Error>> {
+    let config = parse_config(r#"{"port": 8080}"#)?;
+    assert_eq!(config.port, 8080);
+    Ok(()) // Test fails if any ? returns Err
+}
+```
+
+### Testing Panics
+
+```rust
+#[test]
+#[should_panic]
+fn panics_on_empty_input() {
+    process(&[]);
+}
+
+#[test]
+#[should_panic(expected = "index out of bounds")]
+fn panics_with_specific_message() {
+    let v: Vec<i32> = vec![];
+    let _ = v[0];
+}
+```
+
+## Integration Tests
+
+### File Structure
+
+```text
+my_crate/
+├── src/
+│   └── lib.rs
+├── tests/              # Integration tests
+│   ├── api_test.rs     # Each file is a separate test binary
+│   ├── db_test.rs
+│   └── common/         # Shared test utilities
+│       └── mod.rs
+```
+
+### Writing Integration Tests
+
+```rust
+// tests/api_test.rs
+use my_crate::{App, Config};
+
+#[test]
+fn full_request_lifecycle() {
+    let config = Config::test_default();
+    let app = App::new(config);
+
+    let response = app.handle_request("/health");
+    assert_eq!(response.status, 200);
+    assert_eq!(response.body, "OK");
+}
+```
+
+## Async Tests
+
+### With Tokio
+
+```rust
+#[tokio::test]
+async fn fetches_data_successfully() {
+    let client = TestClient::new().await;
+    let result = client.get("/data").await;
+    assert!(result.is_ok());
+    assert_eq!(result.unwrap().items.len(), 3);
+}
+
+#[tokio::test]
+async fn handles_timeout() {
+    use std::time::Duration;
+    let result = tokio::time::timeout(
+        Duration::from_millis(100),
+        slow_operation(),
+    ).await;
+
+    assert!(result.is_err(), "should have timed out");
+}
+```
+
+## Test Organization Patterns
+
+### Parameterized Tests with `rstest`
+
+```rust
+use rstest::{rstest, fixture};
+
+#[rstest]
+#[case("hello", 5)]
+#[case("", 0)]
+#[case("rust", 4)]
+fn test_string_length(#[case] input: &str, #[case] expected: usize) {
+    assert_eq!(input.len(), expected);
+}
+
+// Fixtures
+#[fixture]
+fn test_db() -> TestDb {
+    TestDb::new_in_memory()
+}
+
+#[rstest]
+fn test_insert(test_db: TestDb) {
+    test_db.insert("key", "value");
+    assert_eq!(test_db.get("key"), Some("value".into()));
+}
+```
+
+### Test Helpers
+
+```rust
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Creates a test user with sensible defaults.
+    fn make_user(name: &str) -> User {
+        User::new(name, &format!("{name}@test.com")).unwrap()
+    }
+
+    #[test]
+    fn user_display() {
+        let user = make_user("alice");
+        assert_eq!(user.display_name(), "alice");
+    }
+}
+```
+
+## Property-Based Testing with `proptest`
+
+### Basic Property Tests
+
+```rust
+use proptest::prelude::*;
+
+proptest! {
+    #[test]
+    fn encode_decode_roundtrip(input in ".*") {
+        let encoded = encode(&input);
+        let decoded = decode(&encoded).unwrap();
+        assert_eq!(input, decoded);
+    }
+
+    #[test]
+    fn sort_preserves_length(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
+        let original_len = vec.len();
+        vec.sort();
+        assert_eq!(vec.len(), original_len);
+    }
+
+    #[test]
+    fn sort_produces_ordered_output(mut vec in prop::collection::vec(any::<i32>(), 0..100)) {
+        vec.sort();
+        for window in vec.windows(2) {
+            assert!(window[0] <= window[1]);
+        }
+    }
+}
+```
+
+### Custom Strategies
+
+```rust
+use proptest::prelude::*;
+
+fn valid_email() -> impl Strategy<Value = String> {
+    ("[a-z]{1,10}", "[a-z]{1,5}")
+        .prop_map(|(user, domain)| format!("{user}@{domain}.com"))
+}
+
+proptest! {
+    #[test]
+    fn accepts_valid_emails(email in valid_email()) {
+        assert!(User::new("Test", &email).is_ok());
+    }
+}
+```
+
+## Mocking with `mockall`
+
+### Trait-Based Mocking
+
+```rust
+use mockall::{automock, predicate::eq};
+
+#[automock]
+trait UserRepository {
+    fn find_by_id(&self, id: u64) -> Option<User>;
+    fn save(&self, user: &User) -> Result<(), StorageError>;
+}
+
+#[test]
+fn service_returns_user_when_found() {
+    let mut mock = MockUserRepository::new();
+    mock.expect_find_by_id()
+        .with(eq(42))
+        .times(1)
+        .returning(|_| Some(User { id: 42, name: "Alice".into() }));
+
+    let service = UserService::new(Box::new(mock));
+    let user = service.get_user(42).unwrap();
+    assert_eq!(user.name, "Alice");
+}
+
+#[test]
+fn service_returns_none_when_not_found() {
+    let mut mock = MockUserRepository::new();
+    mock.expect_find_by_id()
+        .returning(|_| None);
+
+    let service = UserService::new(Box::new(mock));
+    assert!(service.get_user(99).is_none());
+}
+```
+
+## Doc Tests
+
+### Executable Documentation
+
+```rust
+/// Adds two numbers together.
+///
+/// # Examples
+///
+/// ```
+/// use my_crate::add;
+///
+/// assert_eq!(add(2, 3), 5);
+/// assert_eq!(add(-1, 1), 0);
+/// ```
+pub fn add(a: i32, b: i32) -> i32 {
+    a + b
+}
+
+/// Parses a config string.
+///
+/// # Errors
+///
+/// Returns `Err` if the input is not valid TOML.
+///
+/// ```no_run
+/// use my_crate::parse_config;
+///
+/// let config = parse_config(r#"port = 8080"#).unwrap();
+/// assert_eq!(config.port, 8080);
+/// ```
+///
+/// ```no_run
+/// use my_crate::parse_config;
+///
+/// assert!(parse_config("}{invalid").is_err());
+/// ```
+pub fn parse_config(input: &str) -> Result<Config, ParseError> {
+    todo!()
+}
+```
+
+## Benchmarking with Criterion
+
+```toml
+# Cargo.toml
+[dev-dependencies]
+criterion = { version = "0.5", features = ["html_reports"] }
+
+[[bench]]
+name = "benchmark"
+harness = false
+```
+
+```rust
+// benches/benchmark.rs
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+
+fn fibonacci(n: u64) -> u64 {
+    match n {
+        0 | 1 => n,
+        _ => fibonacci(n - 1) + fibonacci(n - 2),
+    }
+}
+
+fn bench_fibonacci(c: &mut Criterion) {
+    c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
+}
+
+criterion_group!(benches, bench_fibonacci);
+criterion_main!(benches);
+```
+
+## Test Coverage
+
+### Running Coverage
+
+```bash
+# Install: cargo install cargo-llvm-cov (or use taiki-e/install-action in CI)
+cargo llvm-cov                    # Summary
+cargo llvm-cov --html             # HTML report
+cargo llvm-cov --lcov > lcov.info # LCOV format for CI
+cargo llvm-cov --fail-under-lines 80  # Fail if below threshold
+```
+
+### Coverage Targets
+
+| Code Type | Target |
+|-----------|--------|
+| Critical business logic | 100% |
+| Public API | 90%+ |
+| General code | 80%+ |
+| Generated / FFI bindings | Exclude |
+
+## Testing Commands
+
+```bash
+cargo test                        # Run all tests
+cargo test -- --nocapture         # Show println output
+cargo test test_name              # Run tests matching pattern
+cargo test --lib                  # Unit tests only
+cargo test --test api_test        # Integration tests only
+cargo test --doc                  # Doc tests only
+cargo test --no-fail-fast         # Don't stop on first failure
+cargo test -- --ignored           # Run ignored tests
+```
+
+## Best Practices
+
+**DO:**
+- Write tests FIRST (TDD)
+- Use `#[cfg(test)]` modules for unit tests
+- Test behavior, not implementation
+- Use descriptive test names that explain the scenario
+- Prefer `assert_eq!` over `assert!` for better error messages
+- Use `?` in tests that return `Result` for cleaner error output
+- Keep tests independent — no shared mutable state
+
+**DON'T:**
+- Use `#[should_panic]` when you can test `Result::is_err()` instead
+- Mock everything — prefer integration tests when feasible
+- Ignore flaky tests — fix or quarantine them
+- Use `sleep()` in tests — use channels, barriers, or `tokio::time::pause()`
+- Skip error path testing
+
+## CI Integration
+
+```yaml
+# GitHub Actions
+test:
+  runs-on: ubuntu-latest
+  steps:
+    - uses: actions/checkout@v4
+    - uses: dtolnay/rust-toolchain@stable
+      with:
+        components: clippy, rustfmt
+
+    - name: Check formatting
+      run: cargo fmt --check
+
+    - name: Clippy
+      run: cargo clippy -- -D warnings
+
+    - name: Run tests
+      run: cargo test
+
+    - uses: taiki-e/install-action@cargo-llvm-cov
+
+    - name: Coverage
+      run: cargo llvm-cov --fail-under-lines 80
+```
+
+**Remember**: Tests are documentation. They show how your code is meant to be used. Write them clearly and keep them up to date.