scaffold-tests

name	scaffold_tests
description	Generates unit and regression test files for existing code. Creates "Happy Path", "Edge Case", and "Error" test stubs.

Scaffold Tests

Use this skill to automatically generate test suites for your code, ensuring functionality is locked in.

Inputs

• Target File: The source code specific to test.
• Test Runner: (Optional) Jest, Pytest, etc.

Tooling Strategy

• Use view_file to analyze the source code.
• Use write_to_file to create the test file.

Workflow

1. Context Analysis

• Target: Analyze the open file or the specified module (e.g., utils.py, auth.js).
• Framework Detection: Determine the project's test runner (Jest, PyTest, Mocha, Unittest). If none, suggest the most lightweight option suitable for the user's legacy hardware.

2. Test Strategy

Plan the test coverage:

• Unit Tests: Isolated tests for individual functions/classes.
• Regression Tests: Tests that ensure specific bugs (fixes) don't reappear.
• Naming Convention: Standardize names (e.g., [filename].test.js or test_[filename].py).

3. Generation (The "Safety Net")

Write the test file with three specific sections:

• Happy Path: Standard inputs produce standard outputs (The "It works" check).
• Edge Cases: Nulls, empty strings, zeros, huge numbers (The "Robustness" check).
• Error Handling: Invalid inputs trigger the expected error messages (The "Security" check).

4. Output

• Save the file to a tests/ directory or alongside the source code (based on project convention).
• Prompt the user to run them using /run_tests.

Advanced Testing Patterns

• Test-Driven Development (TDD): Write failing test FIRST, implement minimal code to pass, refactor after green. Never write production code without a failing test.
• Behavior-Driven Testing: Test behavior, not implementation details. Focus on public APIs and business requirements. Use descriptive test names that describe the behavior.
• Factory Pattern: When scaffolding tests, create data factory functions (e.g., getMockUser(overrides)) that provide sensible defaults but allow tests to override specific properties. This keeps tests DRY and maintainable.
• Mocking Strategies: Use factory functions to mock entire modules or specific hooks when scaffolding tests to isolate the unit under test.