# Tdd Stub First

> Test-Driven Development with Stub-First approach.

- Skill: `matrixfounder/tdd-stub-first` (Agent Skill)
- Install (CLI): `npx skillmds@latest add matrixfounder/tdd-stub-first`
- Raw SKILL.md: https://api.skillmd.com/api/skills/matrixfounder/tdd-stub-first/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: MatrixFounder (https://skillmd.com/u/matrixfounder)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/matrixfounder/tdd-stub-first

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# TDD & Stub-First Strategy

## 1. Stubbing Phase
1. **Create Structure:** Files, classes, methods.
2. **Implement Stubs:** Use `NotImplementedError`, `return None`, or hardcoded values.
3. **Docstrings:** Add detailed docstrings describing future logic.
4. **E2E Test (Stub):** Write an E2E test that asserts the hardcoded behavior.
   - *Example:* asserting `discount == 100.0` (stubbed value).

## 2. Implementation Phase
1. **Verify Stubs:** Ensure E2E test passes on stubs.
2. **Replace Stubs:** Implement real logic.
3. **Unit Tests:** Add unit tests for specific methods and edge cases.
4. **Update E2E:** Update E2E test to assert real behavior.
   - *Example:* asserting `discount == 150.0` (calculated value).

## 3. Testing Rules
- **No Mocking LLMs:** Use recorded responses or separate integration environments.
- **Regression:** Always run full regression suite.