TDD Guide

Test-driven development skill for generating unit, integration, and E2E scaffolds; analyzing coverage; and guiding evidence-backed red-green-refactor workflows across Jest, Vitest, Pytest, JUnit, Mocha, and Jasmine adapters.

Table of Contents

• Capabilities
• Workflows
• Tools
• Input Requirements
• Compatibility
• Limitations

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Capabilities

Capability	Description
Test Generation	Convert requirements into distinct unit, integration, or E2E scenarios and templates
Coverage Analysis	Parse LCOV, Istanbul JSON, Cobertura XML, and JaCoCo XML; identify applicable gaps
TDD Workflow	Guide red-green-refactor cycles with phase-specific execution evidence
Framework Adapters	Generate imports, tests, assertions, suites, and setup for every CLI choice
Quality Scoring	Count tests without overlap and score assertions, isolation, naming, and smells on 100 points
Fixture Generation	Create realistic test data, mocks, and factories

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Workflows

Generate Tests from Code

1. Provide requirements as user stories, acceptance criteria, or API specifications.
2. Select --test-type unit, integration, or e2e; each choice changes scenarios, execution scope, and template guidance.
3. Select a compatible target framework and language.
4. Review and replace every generated placeholder assertion.
5. Validation: Compile and run the generated scaffold in the selected project.

Analyze Coverage Gaps

1. Generate LCOV, Istanbul JSON, Cobertura XML, or JaCoCo XML from the project test runner.
2. Run coverage_analyzer.py with a threshold from 0 through 100.
3. Treat null branch coverage as not applicable for branchless files.
4. Review prioritized, file-specific uncovered lines and branches.
5. Validation: Confirm each applicable coverage dimension meets the target.

TDD New Feature

1. Write the test first (RED) and run it.
2. Supply status: failed, failure_kind: assertion or expectation, and a non-empty failure_message.
3. Implement minimal code and supply a passing execution result (GREEN).
4. Refactor while keeping tests green; an unchanged optional refactor is valid.
5. Validation: Advance only when the current phase's structured evidence passes.

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Tools

Scripts are both importable Python modules and command-line tools. Run examples from the skill root (ls/skills/ls-test-driven-development) or adjust paths for your checkout.

Tool	Purpose	Usage
test_generator.py	Generate test cases from requirements JSON	python scripts/test_generator.py --input requirements.json --framework pytest --module auth
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 --requirement "user can sign in"
framework_adapter.py	Generate framework-specific snippets	python scripts/framework_adapter.py --framework pytest --action imports
fixture_generator.py	Generate test data and mocks	python scripts/fixture_generator.py mock-data --schema-file schema.json --count 5
metrics_calculator.py	Calculate test quality metrics	python scripts/metrics_calculator.py --source app.py --tests test_app.py
format_detector.py	Detect language and framework	python scripts/format_detector.py --file source.ts
output_formatter.py	Format JSON output for CLI/desktop/API	python scripts/output_formatter.py --kind coverage --input summary.json

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Input Requirements

For Test Generation:

• Source code (file path or pasted content)
• Compatible framework/language pair (see the authoritative compatibility matrix)
• Test scope: unit, integration, or e2e

For Coverage Analysis:

• Coverage report file in LCOV, Istanbul JSON, Cobertura XML, or JaCoCo XML
• Optional source context
• Threshold from 0 through 100

For TDD Workflow:

• Feature requirements or user story
• Current phase (RED, GREEN, REFACTOR)
• Test code and implementation status

Compatibility

Use the single authoritative compatibility matrix and upstream sources. Do not copy version floors into secondary references.

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Limitations

Scope	Details
Generated scope	Unit, integration, and E2E outputs are scaffolds; replace placeholders and supply project-specific setup
Static analysis	Scripts do not execute tests; callers supply structured execution evidence
Language support	Best for TypeScript, JavaScript, Python, and Java
Report formats	Native support is LCOV, Istanbul JSON, Cobertura XML, and JaCoCo XML
Generated tests	Require human review for domain assertions and complex orchestration

When to use other tools:

• E2E testing: Playwright, Cypress, Selenium
• Performance testing: k6, JMeter, Locust
• Security testing: OWASP ZAP, Burp Suite

2026-07 Refresh Note

Refresh classification: existing LocalSetup-native TDD coverage remains the target for TDD imports. Do not create a duplicate ls-tdd-skill; route TDD requests here and use ls-write-run-tests for framework-specific commands.