# Nikoheikkila Agents Tdd Green > TDD Green Phase - Make Tests Pass Quickly - Skill: `tomevault-io/nikoheikkila-agents-tdd-green` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/nikoheikkila-agents-tdd-green` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/nikoheikkila-agents-tdd-green/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/nikoheikkila-agents-tdd-green --- # TDD Green Phase - Make Tests Pass Quickly Write the minimal code necessary to make unit tests provided by the user as a context to pass. **Do not write any more code than required.** ## Mandatory Rules - **Do not change the tests** - Never touch the unit test code during this phase. - **Always stay in the scope** - Implement only what's required to make the test pass, avoid scope creep. - **Minimum viable solution** - Focus on core requirements from the test. ## Core Principles - **Fake it till you make it** - Start with hard-coded returns based on what the test expects, then generalize as needed. - **Obvious implementation** - When the solution is clear from the test, implement it directly. - **Green bar quickly** - Prioritize making tests pass over code quality, design, or optimization efforts. - **Ignore code smells temporarily** - Duplication and poor design will be addressed in the refactor phase later. - **Simple solutions first** - Choose the most straightforward implementation path. - **Defer complexity** - Don't anticipate requirements beyond the current test scope. ## Implementation Strategies - **Use the simplest language features** - Add crude if/else and for/while logic, don't use mapping, filtering, reducing or similar advanced array methods. - **Use basic collection types** - Use simple arrays and objects over more complex data structures. ## Error Handling - **Minimal exception handling** - Only handle exceptions if the test explicitly expects them. - **Let failures propagate** - Don't add try/catch blocks unless required by the test. - **Match expected errors** - Return exact error messages or types the test assertions check for. - **No defensive programming** - Skip input validation unless tests demand it. ## Test Isolation & Execution - **Run tests independently** - Ensure each test passes in isolation, not just as part of the full test suite. - **No shared state** - Avoid using module-level state or global variables that could leak between tests. - **Order independence** - Tests should pass regardless of execution order. - **One assertion at a time** - If a test has multiple assertions, make them pass incrementally. ## File & Module Structure - **Mirror test imports** - Create files exactly where the test expects to import from. - **Match signatures exactly** - Function names, parameters, and return types must align with test calls. - **Minimal imports** - Only import what's immediately needed to make the test pass. - **No premature abstraction** - Keep code in the module under test, don't extract any helper modules. ## Transformation Priority Premise Apply the simplest transformation that makes the test pass, in this order: 1. **{}->nil** - No code to `None` 2. **nil->constant** - Return a hard-coded value (e.g. string) 3. **constant->constant+** - Add another hard-coded value (e.g. number) 4. **constant->scalar** - Replace constant with a variable 5. **statement->statements** - Add more statements 6. **unconditional->if** - Add a conditional for handling branched logic 7. **scalar->array** - Use a collection 8. **array->container** - Use a more complex structure 9. **statement->recursion** - Add recursive logic (only if needed) Start at the top. Never jump directly to complex solutions. ## Common Pitfalls to Avoid - **No logging or printing statements** - Do not leave debugging statements around. - **No comments or documentation strings** - Documentation belongs in the refactor phase. - **No type hints** - Typing belongs in the refactor phase. - **No premature optimization** - Brute force solutions are acceptable if they pass. - **No extra validation** - Only validate what the test checks. - **No configuration files** - Use hard-coded values instead. - **No new dependencies** - Only use libraries already in test setup. Never install new packages. ## Handling Multiple Failing Tests - **Pick the simplest first** - Start with the most basic or foundational test. - **One test at a time** - Focus on making one test pass before moving to the next one. - **Run frequently** - Execute tests after each small code change. ## External Dependencies - **Honor test doubles** - Inject external dependencies only as the test requires. - **No real or asynchronous I/O** - Don't access databases, files, or network layers to keep tests fast. - **Hard-code external data** - Return fixed stub responses instead of calling external services. ## Success Criteria - **All tests pass** - Green bar with all tests passing. - **No test modifications** - Test files remain unchanged. - **Fast execution** - Tests run quickly (seconds, not minutes). - **Warnings are acceptable** - Warnings can be addressed in the refactor phase. - **Minimal implementation** - Code does not do more than required. ## Execution Guidelines 1. **Review test requirements** - Confirm the test case is understood before implementation. 2. **Run the failing test** - Analyze exactly what needs to be implemented by running tests first. 3. **Write minimal code** - Add just enough code to make the test pass. 4. **Run all tests** - Ensure new code doesn't break existing functionality. ## Green Phase Checklist - [ ] All tests are passing (green bar) - [ ] No more code written than necessary for test scope - [ ] Existing tests remain passing - [ ] Implementation is simple and direct - [ ] Test acceptance criteria satisfied - [ ] The code is ready for the refactoring phase --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/nikoheikkila) — claim your Tome and manage your conversions.