/test-generation

name: test-generation
description: Generate comprehensive test suites for existing code. Use when asked to write tests, add test coverage, create unit tests, or build integration tests.
license: MIT
compatibility: Requires pytest (Python) or vitest/jest (Node.js)

Process

1. **Read the source code.** Load every function and class under test. Do not write tests from a summary or description — you must see the implementation.

2. **Identify the test framework.** Check for:

• `conftest.py` or `pytest.ini` → pytest
• `vitest.config.*` → Vitest
• `jest.config.*` → Jest

If none are found, default to pytest for Python, Vitest for TypeScript/JavaScript.

3. **Categorize test types needed:**

• **Happy path:** Normal inputs, expected outputs
• **Edge cases:** Empty inputs, None/null, boundary values, maximum lengths
• **Error cases:** Invalid inputs that should raise exceptions or return errors
• **Integration:** Tests that verify multiple components work together

4. **Write tests following the AAA pattern:**

   def test_descriptive_name():
       # Arrange — set up inputs and expected state
       user = create_test_user(name="Alice")
       
       # Act — call the function under test
       result = get_user_greeting(user)
       
       # Assert — verify the output
       assert result == "Hello, Alice!"

5. **Name tests descriptively.** The test name should describe the scenario and expected outcome:

• ✅ `test_login_rejects_empty_password`
• ❌ `test_login_2`

6. **Run the tests.** Execute the full test suite and confirm all tests pass. If any fail, fix the test (not the source code) unless you discover an actual bug.

Rationalizations

| Excuse | Rebuttal | |--------|----------| | "I'll just write happy path tests" | Edge cases are where bugs live. Write at least one edge case per function. | | "The function is too simple to test" | Simple functions get refactored. Tests protect against regressions during refactoring. | | "I'll add tests later" | You won't. Write them now. | | "Mocking everything is fine" | Over-mocking hides integration bugs. Mock external services, not your own code. |

Verification

• [ ] Tests were executed (not just written)
• [ ] All tests pass
• [ ] At least one edge case test exists per function
• [ ] Test names describe the scenario, not just "test_1", "test_2"