What problem does it solve?
Writing tests before implementation requires knowing a codebase's test framework, file layout, and assertion style, which is tedious to discover manually. This Skill automates the red phase of red-green-refactor by discovering existing test conventions and generating failing tests that define expected behavior before the implementation exists.
Core Features & Use Cases
- Convention Discovery: Scans build files, existing test files, and CI configuration to detect the language, test framework, naming patterns, and test command already in use.
- Red-Phase Test Generation: Writes syntactically valid test files that fail because the implementation does not yet exist, covering acceptance criteria while skipping trivial or non-testable deliverables like documentation.
- Fallback Conventions: Applies a language-specific fallback table (pytest, Vitest, JUnit, testthat, and more) when no existing tests can be found, including minimal framework setup.
- Use Case: Given a slice with acceptance criteria for a new URL validation utility in a TypeScript package, the Skill detects Vitest from package.json, writes failing tests in the conventional location, and reports the exact command to run them.
Quick Start
Write failing tests for the current slice using its acceptance criteria and target packages, following the test conventions already present in this repository.
