modbender TDD Guide
Test-driven development skill for generating tests, analyzing coverage, and guiding red-green-refactor workflows across Jest, Pytest, JUnit, and Vitest.
Table of Contents
Capabilities
| Capability | Description |
|---|---|
| Test Generation | Convert requirements or code into test cases with proper structure |
| Coverage Analysis | Parse LCOV/JSON/XML reports, identify gaps, prioritize fixes |
| TDD Workflow | Guide red-green-refactor cycles with validation |
| Framework Adapters | Generate tests for Jest, Pytest, JUnit, Vitest, Mocha |
| Quality Scoring | Assess test isolation, assertions, naming, detect test smells |
| Fixture Generation | Create realistic test data, mocks, and factories |
Workflows
Generate Tests from Code
- Provide source code (TypeScript, JavaScript, Python, Java)
- Specify target framework (Jest, Pytest, JUnit, Vitest)
- Run
test_generator.pywith requirements - Review generated test stubs
- Validation: Tests compile and cover happy path, error cases, edge cases
Analyze Coverage Gaps
- Generate coverage report from test runner (
npm test -- --coverage) - Run
coverage_analyzer.pyon LCOV/JSON/XML report - Review prioritized gaps (P0/P1/P2)
- Generate missing tests for uncovered paths
- Validation: Coverage meets target threshold (typically 80%+)
TDD New Feature
- Write failing test first (RED)
- Run
tdd_workflow.py --phase redto validate - Implement minimal code to pass (GREEN)
- Run
tdd_workflow.py --phase greento validate - Refactor while keeping tests green (REFACTOR)
- Validation: All tests pass after each cycle
Tools
| Tool | Purpose | Usage |
|---|---|---|
test_generator.py |
Generate test cases from code/requirements | python scripts/test_generator.py --input source.py --framework pytest |
coverage_analyzer.py |
Parse and analyze coverage reports | python scripts/coverage_analyzer.py --report lcov.info --threshold 80 |
tdd_workflow.py |
Guide red-green-refactor cycles | python scripts/tdd_workflow.py --phase red --test test_auth.py |
framework_adapter.py |
Convert tests between frameworks | python scripts/framework_adapter.py --from jest --to pytest |
fixture_generator.py |
Generate test data and mocks | python scripts/fixture_generator.py --entity User --count 5 |
metrics_calculator.py |
Calculate test quality metrics | python scripts/metrics_calculator.py --tests tests/ |
format_detector.py |
Detect language and framework | python scripts/format_detector.py --file source.ts |
output_formatter.py |
Format output for CLI/desktop/CI | python scripts/output_formatter.py --format markdown |
Input Requirements
For Test Generation:
- Source code (file path or pasted content)
- Target framework (Jest, Pytest, JUnit, Vitest)
- Coverage scope (unit, integration, edge cases)
For Coverage Analysis:
- Coverage report file (LCOV, JSON, or XML format)
- Optional: Source code for context
- Optional: Target threshold percentage
For TDD Workflow:
- Feature requirements or user story
- Current phase (RED, GREEN, REFACTOR)
- Test code and implementation status
Limitations
| Scope | Details |
|---|---|
| Unit test focus | Integration and E2E tests require different patterns |
| Static analysis | Cannot execute tests or measure runtime behavior |
| Language support | Best for TypeScript, JavaScript, Python, Java |
| Report formats | LCOV, JSON, XML only; other formats need conversion |
| Generated tests | Provide scaffolding; require human review for complex logic |
When to use other tools:
- E2E testing: Playwright, Cypress, Selenium
- Performance testing: k6, JMeter, Locust
- Security testing: OWASP ZAP, Burp Suite