unit-test

name	unit-test
description	Run and write Jest unit tests following Middle Earth patterns.

Run and write Jest unit tests following Middle Earth patterns.

Running tests

# Test a specific project
pnpm nx test <project-name>

# Test all projects
pnpm nx run-many --target test

File structure

Tests are colocated with source in __tests__/ directories:

src/lib/
├── my-component.ts
├── __tests__/
│   └── my-component.spec.ts

Test patterns

React components (Testing Library):

import { render, screen } from '@testing-library/react';
import { Button } from '../button';

describe('Button', () => {
  it('renders with label', () => {
    render(<Button>Click me</Button>);
    expect(screen.getByText('Click me')).toBeInTheDocument();
  });
});

Table-driven tests:

it.each([
  ['valid input', validData, true],
  ['invalid input', invalidData, false],
])('validates %s', (_, input, expected) => {
  expect(isValid(input)).toBe(expected);
});

What NOT to do

• No .only in tests (disallowed by lint rule)
• No any type assertions
• No testing implementation details (test behavior)

Coverage

Aim for 100% coverage where feasible. Use expect.objectContaining for flexible assertions.