implementation-workflow（实施工作流程）

Skill: TDD Implementation

When to use this skill

• Implementing new features
• Major refactoring
• Complex bug fixes

Available templates

TDD Workflow (Test-Driven Development)

Phase 1: Understand

1. Read existing documentation

- GLOBAL_APP_DESCRIPTION.md for global context - docs/STRATEGIES.md if related to trading

1. Identify affected modules

- Which DDD layer? (domain/application/infrastructure) - Which existing files will be impacted?

1. Verify architecture domain/ → Pure business logic, no I/O application/ → Orchestration, services, use cases infrastructure/ → I/O, external APIs, persistence

Phase 2: Write tests FIRST

Fundamental rule: Tests are written BEFORE implementation code.

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

    #[test]
    fn test_new_feature_basic_case() {
        // Arrange
        let input = ...;

        // Act
        let result = new_feature(input);

        // Assert
        assert_eq!(result, expected);
    }

    #[test]
    fn test_new_feature_edge_case() {
        // Test edge cases
    }

    #[test]
    fn test_new_feature_error_case() {
        // Test error cases
    }
}

Tests MUST fail at this stage (red phase).

Phase 3: Implement

1. Minimal code to make tests pass
2. Respect DDD architecture
3. No .unwrap() in production code
4. Use Decimal for amounts

// ❌ Avoid
fn process(value: f64) -> f64 {
    some_operation(value).unwrap()
}

// ✅ Prefer
fn process(value: Decimal) -> Result<Decimal, ProcessError> {
    some_operation(value).map_err(ProcessError::from)
}

Phase 4: Refactor

1. Clean the code

- Remove duplicate code - Remove commented-out code and obsolete comments - Improve variable names - Simplify complex expressions

1. Add documentation

- Rustdoc on public functions - Comments for complex logic

1. Verify with clippy cargo clippy --all-targets -- -D warnings

Phase 5: Validate

1. Invoke the testing skill

- cargo fmt - cargo clippy - cargo test

1. Invoke the documentation skill

- Update GLOBAL_APP_DESCRIPTION.md - Add entry in GLOBAL_APP_DESCRIPTION_VERSIONS.md - Increment version

Complete example

// 1. First the test
#[test]
fn test_calculate_position_size() {
    let capital = Decimal::from(10000);
    let risk_pct = Decimal::from_str("0.02").unwrap();
    let stop_loss = Decimal::from_str("0.05").unwrap();

    let size = calculate_position_size(capital, risk_pct, stop_loss);

    assert_eq!(size, Decimal::from(4000)); // 2% risk, 5% stop = 40% position
}

// 2. Then the implementation
pub fn calculate_position_size(
    capital: Decimal,
    risk_percentage: Decimal,
    stop_loss_percentage: Decimal,
) -> Decimal {
    let risk_amount = capital * risk_percentage;
    risk_amount / stop_loss_percentage
}

Anti-patterns to avoid