profpowell Unit Testing Skill
Write and maintain unit tests for JavaScript files using Node.js native test runner.
When Tests Are Required
| Scenario | Test Required | Notes |
|---|---|---|
New script in .claude/scripts/ |
Yes | Every new script needs tests |
| Bug fix | Yes | Test should reproduce and verify fix |
| Refactoring | Verify existing | Ensure tests still pass |
Components in src/ |
Optional | Encouraged but not enforced |
Test File Convention
.claude/scripts/foo-bar.js → .claude/test/validators/foo-bar.test.js
.claude/scripts/health-check.js → .claude/test/validators/health-check.test.js
Quick Start Template
import { describe, it } from 'node:test';
import assert from 'node:assert';
import { execSync } from 'node:child_process';
import { resolve } from 'node:path';
const projectRoot = resolve(import.meta.dirname, '../..');
describe('Script Name', () => {
describe('Valid Cases', () => {
it('should pass for valid input', () => {
// Test implementation
assert.strictEqual(result, expected);
});
});
describe('Invalid Cases', () => {
it('should fail for invalid input', () => {
// Test implementation
assert.ok(result.includes('error'));
});
});
});
Node.js Test Runner Basics
Imports
import { describe, it, before, after, beforeEach, afterEach } from 'node:test';
import assert from 'node:assert';
Assertions
| Method | Use Case |
|---|---|
assert.strictEqual(a, b) |
Exact equality |
assert.ok(value) |
Truthy check |
assert.match(str, /regex/) |
Pattern matching |
assert.throws(fn) |
Exception expected |
assert.rejects(promise) |
Async rejection expected |
assert.deepStrictEqual(a, b) |
Object/array equality |
Running Tests
npm test # Run all tests
npm run test:all # Run with native runner
node --test .claude/test/validators/foo.test.js # Single file
npm run test:coverage # Check test coverage
Minimum Test Requirements
Every script test file should include:
- Happy path test - Normal operation succeeds
- Error handling test - Invalid input handled gracefully
- Edge case test - Boundary conditions covered
Test Organization
describe('Script Name', () => {
// Setup/teardown if needed
before(() => { /* one-time setup */ });
after(() => { /* one-time cleanup */ });
describe('Feature A', () => {
it('should do X when Y', () => {});
it('should handle Z gracefully', () => {});
});
describe('Feature B', () => {
it('should produce expected output', () => {});
});
});
CLI Tool Testing Pattern
Most scripts are CLI tools. Test them by executing with execSync:
function runScript(args = '') {
try {
const output = execSync(
`node .claude/scripts/my-script.js ${args}`,
{ cwd: projectRoot, encoding: 'utf-8' }
);
return { success: true, output };
} catch (error) {
return {
success: false,
output: error.stdout || '',
error: error.stderr || ''
};
}
}
it('should show help with --help flag', () => {
const result = runScript('--help');
assert.ok(result.success);
assert.match(result.output, /Usage:/);
});
Fixtures
- Valid fixtures:
.claude/test/fixtures/valid/ - Invalid fixtures:
.claude/test/fixtures/invalid/<validator-name>/
See FIXTURES.md for fixture organization patterns.
Related Documentation
- PATTERNS.md - Common test patterns
- FIXTURES.md - Fixture organization
- javascript-author skill - Code style
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