/implementation

You are starting Test-Driven Development for tasks defined in docs/plans/tasks.yaml.

TDD Workflow

For each task, follow the Red-Green-Refactor cycle:

1. RED: Write Failing Tests First

Before writing any implementation:

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

    #[test]
    fn test_req_001_acceptance_criterion() {
        // Test the acceptance criteria from tasks.yaml
        // This test MUST fail initially (no implementation exists)
    }
}

• One test per acceptance criterion
• Name tests test_req_NNN_* for traceability
• Run cargo test - confirm tests fail (red)

2. GREEN: Minimal Implementation

Write the minimum code to make tests pass:

cargo test           # Must pass
cargo build          # Must pass
cargo clippy -- -D warnings  # No warnings allowed

• Only add code that tests require
• No speculative features
• No unused code paths

3. REFACTOR: Remove Uncovered Code

With tests covering all requirements, aggressively refactor:

cargo llvm-cov --html  # Generate coverage report

• Delete any uncovered code - if tests don't need it, remove it
• Simplify implementations
• Extract common patterns
• Tests must still pass after refactoring

Cargo Requirements

All cargo commands must pass without warnings:

cargo build --all-targets 2>&1 | grep -E "^warning:" && exit 1
cargo test --all-features
cargo clippy --all-targets -- -D warnings
cargo fmt --check

The make verify target enforces these.

Task Cycle

1. Select Ready Task

Tasks are ready when status: pending and all deps are complete.

2. Mark In Progress

- id: task-001
  status: in_progress

3. Read Specification

If task has spec_file, read it for detailed requirements.

4. TDD Cycle

RED    → Write failing test for acceptance criterion
GREEN  → Write minimal code to pass
REFACTOR → Remove uncovered code, simplify

Repeat for each acceptance criterion.

5. Verify

make verify  # Must pass: build, test, clippy, fmt

6. Mark Complete

- id: task-001
  status: complete

Coverage-Driven Refactoring

In the refactor step:

1. Run coverage: cargo llvm-cov
2. Identify uncovered lines
3. For each uncovered line, ask: "Is this required by any test?"
4. If no test requires it → delete it
5. If a test should require it → add a test first

This ensures:

• All code is justified by requirements
• Dead code is eliminated
• Implementation is minimal

Verification Gate

The Stop hook blocks until make verify passes:

• cargo build --all-targets (no warnings)
• cargo test --all-features (all pass)
• cargo clippy -- -D warnings (no warnings)
• cargo fmt --check (formatted)

Commands

• /swiss-cheese:design - Create task specification
• /swiss-cheese:implementation - Begin TDD implementation