Test Writer
Overview
Analyzes source code and auto-generates comprehensive unit and integration tests.
When to Use
- User asks to "write tests" or "add test coverage"
- User wants to "test this function"
How It Works
Step 1: Detect test framework
Check: package.json (jest/mocha), pytest.ini, pyproject.toml, conftest.py
Step 2: Parse source
Read source files. Identify: function signatures, parameters, return types, error handling, edge cases.
Step 3: Generate test cases
For each function generate: happy path, edge cases (empty/null/zero), error cases, boundary cases.
Step 4: Write test file
JavaScript: tests/filename.test.js or filename.test.js
Python: tests/test_filename.py
Templates
Jest
describe('functionName', () => {
test('should return expected result', () => {
expect(functionName(input)).toBe(expected);
});
test('should throw for invalid input', () => {
expect(() => functionName(invalid)).toThrow();
});
});
Pytest
def test_function_normal():
assert function_name(input) == expected
def test_function_invalid():
with pytest.raises(ErrorType):
function_name(invalid)
Tips
- Target 80%+ coverage on critical functions
- Cover all branches and error paths
- Mock external dependencies (API, filesystem, DB)
