# Development Documentation

This directory contains comprehensive documentation for Ruchy compiler development, with a focus on quality engineering and testing practices.

## Coverage Sprint Documentation (QUALITY-001 to QUALITY-006)

### Executive Reports
- **[COVERAGE_FINAL_REPORT.md](COVERAGE_FINAL_REPORT.md)** - Complete analysis and recommendations
- **[coverage-sprint-final-summary.md](coverage-sprint-final-summary.md)** - Concise executive summary
- **[sprint-summary-2025-08-25.md](sprint-summary-2025-08-25.md)** - Daily sprint log

### Technical Analysis
- **[parser-limitations.md](parser-limitations.md)** - Detailed parser gaps blocking tests
- **[coverage-gap-analysis.md](coverage-gap-analysis.md)** - Path to 70% coverage targets
- **[coverage-report-phase1.md](coverage-report-phase1.md)** - Phase 1 detailed findings

### Tools and Infrastructure
- **[coverage.md](coverage.md)** - Usage guide for coverage tools and scripts

## Key Findings Summary

### 🏆 Major Achievements
- **126 tests created** across 13 test files
- **70% improvement** in transpiler coverage (32% → 54.85%)
- **Complete testing infrastructure** established
- **Parser limitations identified** as primary blocker

### 🔬 Critical Discovery
Parser limitations prevent ~40% of transpiler functionality from being tested:
- Pattern guards (`n if n > 0`)
- Or-patterns (`1 | 2 | 3`)
- Rest patterns (`[first, ..rest]`)
- Complex string interpolation
- Advanced type annotations

### 💡 Innovation
Created **Direct AST Construction** approach using AstBuilder to bypass parser limitations entirely.

### 📊 Current Status
- **Overall Coverage**: 37.13%
- **Transpiler**: 54.85% 
- **Interpreter**: 69.57%
- **REPL**: 8.33% (17 tests created)

## Next Steps

### High Priority (QUALITY-007)
1. **Parser Enhancement** - Fix limitations to unblock 40 existing tests
2. **Coverage Regression Prevention** - Maintain current baseline
3. **Integration Testing** - More effective for complex modules

### Medium Priority (QUALITY-008 to QUALITY-012)
1. **Performance Benchmarking** - Systematic performance analysis
2. **Fuzzing Infrastructure** - Automated robustness testing  
3. **Property Testing** - Mathematical invariant verification
4. **Release Preparation** - Quality gates for v1.17.0

## Development Workflow

### Before Making Changes
1. Check current coverage: `make coverage-quick`
2. Review parser limitations if adding transpiler tests
3. Consider direct AST construction for advanced features

### After Making Changes  
1. Run full coverage analysis: `make coverage`
2. Ensure coverage doesn't decrease
3. Update documentation if significant changes

### Testing Strategy
- **Unit Tests**: For isolated functionality
- **Integration Tests**: For cross-module behavior
- **Direct AST Tests**: For parser-blocked features
- **Property Tests**: For invariant verification

## Resources

### Tools
- Coverage scripts in `/scripts/`
- Makefile targets: `make coverage`, `make coverage-quick`
- AstBuilder for direct AST construction

### References
- Toyota Way quality principles (CLAUDE.md)
- Systematic testing methodology
- Coverage gap analysis and recommendations

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*This documentation follows the Toyota Way principle of systematic problem-solving and continuous improvement. All findings are reproducible and actionable.*