GROWI Testing Patterns

GROWI uses Vitest for all testing (unit, integration, component). This skill covers universal testing patterns applicable across the monorepo.

Test File Placement (Global Standard)

Place test files in the same directory as the source file:

code

src/components/Button/
├── Button.tsx
└── Button.spec.tsx       # Component test

src/utils/
├── helper.ts
└── helper.spec.ts        # Unit test

src/services/api/
├── pageService.ts
└── pageService.integ.ts  # Integration test

Test Types & Environments

File Pattern	Type	Environment	Use Case
`*.spec.{ts,js}`	Unit Test	Node.js	Pure functions, utilities, services
`*.integ.ts`	Integration Test	Node.js + DB	API routes, database operations
`*.spec.{tsx,jsx}`	Component Test	happy-dom	React components

Vitest automatically selects the environment based on file extension and configuration.

Vitest Configuration

Global APIs (No Imports Needed)

All GROWI packages configure Vitest globals in tsconfig.json:

json

{
  "compilerOptions": {
    "types": ["vitest/globals"]
  }
}

This enables auto-import of testing APIs:

typescript

// No imports needed!
describe('MyComponent', () => {
  it('should render', () => {
    expect(true).toBe(true);
  });

  beforeEach(() => {
    // Setup
  });

  afterEach(() => {
    // Cleanup
  });
});

Available globals: describe, it, test, expect, beforeEach, afterEach, beforeAll, afterAll, vi

Type-Safe Mocking with vitest-mock-extended

Basic Usage

vitest-mock-extended provides fully type-safe mocks with TypeScript autocomplete:

typescript

import { mockDeep, type DeepMockProxy } from 'vitest-mock-extended';

// Create type-safe mock
const mockRouter: DeepMockProxy<NextRouter> = mockDeep<NextRouter>();

// TypeScript autocomplete works!
mockRouter.asPath = '/test-path';
mockRouter.query = { id: '123' };
mockRouter.push.mockResolvedValue(true);

// Use in tests
expect(mockRouter.push).toHaveBeenCalledWith('/new-path');

Complex Types with Optional Properties

typescript

interface ComplexProps {
  currentPageId?: string | null;
  currentPathname?: string | null;
  data?: Record<string, unknown>;
  onSubmit?: (value: string) => void;
}

const mockProps: DeepMockProxy<ComplexProps> = mockDeep<ComplexProps>();
mockProps.currentPageId = 'page-123';
mockProps.data = { key: 'value' };
mockProps.onSubmit?.mockImplementation((value) => {
  console.log(value);
});

Why vitest-mock-extended?

•✅ Type safety: Catches typos at compile time
•✅ Autocomplete: IDE suggestions for all properties/methods
•✅ Deep mocking: Automatically mocks nested objects
•✅ Vitest integration: Works seamlessly with vi.fn()

React Testing Library Patterns

Basic Component Test

typescript

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

describe('Button', () => {
  it('should render with text', () => {
    const { getByText } = render(<Button>Click me</Button>);
    expect(getByText('Click me')).toBeInTheDocument();
  });

  it('should call onClick when clicked', async () => {
    const onClick = vi.fn();
    const { getByRole } = render(<Button onClick={onClick}>Click</Button>);

    const button = getByRole('button');
    await userEvent.click(button);

    expect(onClick).toHaveBeenCalledTimes(1);
  });
});

Testing with Jotai (Global Pattern)

When testing components that use Jotai atoms, wrap with <Provider>:

typescript

import { render } from '@testing-library/react';
import { Provider } from 'jotai';

const renderWithJotai = (ui: React.ReactElement) => {
  const Wrapper = ({ children }: { children: React.ReactNode }) => (
    <Provider>{children}</Provider>
  );
  return render(ui, { wrapper: Wrapper });
};

describe('ComponentWithJotai', () => {
  it('should render with atom state', () => {
    const { getByText } = renderWithJotai(<MyComponent />);
    expect(getByText('Hello')).toBeInTheDocument();
  });
});

Isolated Jotai Scope (For Testing)

To isolate atom state between tests:

typescript

import { createScope } from 'jotai-scope';

describe('ComponentWithIsolatedState', () => {
  it('test 1', () => {
    const scope = createScope();
    const { getByText } = renderWithJotai(<MyComponent />, scope);
    // ...
  });

  it('test 2', () => {
    const scope = createScope(); // Fresh scope
    const { getByText } = renderWithJotai(<MyComponent />, scope);
    // ...
  });
});

Async Testing Patterns (Global Standard)

Using `act()` and `waitFor()`

When testing async state updates:

typescript

import { waitFor, act } from '@testing-library/react';
import { renderHook } from '@testing-library/react';

test('async hook', async () => {
  const { result } = renderHook(() => useMyAsyncHook());

  // Trigger async action
  await act(async () => {
    result.current.triggerAsyncAction();
  });

  // Wait for state update
  await waitFor(() => {
    expect(result.current.isLoading).toBe(false);
  });

  expect(result.current.data).toBeDefined();
});

Testing Async Functions

typescript

it('should fetch data successfully', async () => {
  const data = await fetchData();
  expect(data).toEqual({ id: '123', name: 'Test' });
});

it('should handle errors', async () => {
  await expect(fetchDataWithError()).rejects.toThrow('Error');
});

Advanced Assertions

Object Matching

typescript

expect(mockFunction).toHaveBeenCalledWith(
  expect.objectContaining({
    pathname: '/expected-path',
    data: expect.any(Object),
    timestamp: expect.any(Number),
  })
);

Array Matching

typescript

expect(result).toEqual(
  expect.arrayContaining([
    expect.objectContaining({ id: '123' }),
    expect.objectContaining({ id: '456' }),
  ])
);

Partial Matching

typescript

expect(user).toMatchObject({
  name: 'John',
  email: 'john@example.com',
  // Other properties are ignored
});

Test Structure Best Practices

AAA Pattern (Arrange-Act-Assert)

typescript

describe('MyComponent', () => {
  beforeEach(() => {
    vi.clearAllMocks(); // Clear mocks before each test
  });

  describe('rendering', () => {
    it('should render with default props', () => {
      // Arrange: Setup test data
      const props = { title: 'Test' };

      // Act: Render component
      const { getByText } = render(<MyComponent {...props} />);

      // Assert: Verify output
      expect(getByText('Test')).toBeInTheDocument();
    });
  });

  describe('user interactions', () => {
    it('should submit form on button click', async () => {
      // Arrange
      const onSubmit = vi.fn();
      const { getByRole, getByLabelText } = render(
        <MyForm onSubmit={onSubmit} />
      );

      // Act
      await userEvent.type(getByLabelText('Name'), 'John');
      await userEvent.click(getByRole('button', { name: 'Submit' }));

      // Assert
      expect(onSubmit).toHaveBeenCalledWith({ name: 'John' });
    });
  });
});

Nested `describe` for Organization

typescript

describe('PageService', () => {
  describe('createPage', () => {
    it('should create a page successfully', async () => {
      // ...
    });

    it('should throw error if path is invalid', async () => {
      // ...
    });
  });

  describe('updatePage', () => {
    it('should update page content', async () => {
      // ...
    });
  });
});

Common Mocking Patterns

Mocking SWR

typescript

vi.mock('swr', () => ({
  default: vi.fn(() => ({
    data: mockData,
    error: null,
    isLoading: false,
    mutate: vi.fn(),
  })),
}));

Mocking Modules

typescript

// Mock entire module
vi.mock('~/services/PageService', () => ({
  PageService: {
    findById: vi.fn().mockResolvedValue({ id: '123', title: 'Test' }),
    create: vi.fn().mockResolvedValue({ id: '456', title: 'New' }),
  },
}));

// Use in test
import { PageService } from '~/services/PageService';

it('should call PageService.findById', async () => {
  await myFunction();
  expect(PageService.findById).toHaveBeenCalledWith('123');
});

Mocking Specific Functions

typescript

import { myFunction } from '~/utils/myUtils';

vi.mock('~/utils/myUtils', () => ({
  myFunction: vi.fn().mockReturnValue('mocked'),
  otherFunction: vi.fn(), // Mock other exports
}));

Integration Tests (with Database)

Integration tests (*.integ.ts) can access in-memory databases:

typescript

describe('PageService Integration', () => {
  beforeEach(async () => {
    // Setup: Seed test data
    await Page.create({ path: '/test', body: 'content' });
  });

  afterEach(async () => {
    // Cleanup: Clear database
    await Page.deleteMany({});
  });

  it('should create a page', async () => {
    const page = await PageService.create({
      path: '/new-page',
      body: 'content',
    });

    expect(page._id).toBeDefined();
    expect(page.path).toBe('/new-page');
  });
});

Testing Checklist

Before committing tests, ensure:

•✅ Co-location: Test files are next to source files
•✅ Descriptive names: Test descriptions clearly state what is being tested
•✅ AAA pattern: Tests follow Arrange-Act-Assert structure
•✅ Mocks cleared: Use beforeEach(() => vi.clearAllMocks())
•✅ Async handled: Use async/await and waitFor() for async operations
•✅ Type safety: Use vitest-mock-extended for type-safe mocks
•✅ Isolated state: Jotai tests use separate scopes if needed

Running Tests

bash

# Run all tests for a package
turbo run test --filter @growi/app

# Run specific test file
cd {package_dir} && pnpm vitest run src/components/Button/Button.spec.tsx

Summary: GROWI Testing Philosophy

•Co-locate tests: Keep tests close to source code
•Type-safe mocks: Use vitest-mock-extended for TypeScript support
•React Testing Library: Test user behavior, not implementation details
•Async patterns: Use act() and waitFor() for async state updates
•Jotai integration: Wrap components with <Provider> for atom state
•Clear structure: Use nested describe and AAA pattern
•Clean mocks: Always clear mocks between tests

These patterns apply to all GROWI packages with React/TypeScript code.

GROWI Testing Patterns

Test File Placement (Global Standard)

Test Types & Environments

Vitest Configuration

Global APIs (No Imports Needed)

Type-Safe Mocking with vitest-mock-extended

Basic Usage

Complex Types with Optional Properties

Why vitest-mock-extended?

React Testing Library Patterns

Basic Component Test

Testing with Jotai (Global Pattern)

Isolated Jotai Scope (For Testing)

Async Testing Patterns (Global Standard)

Using act() and waitFor()

Testing Async Functions

Advanced Assertions

Object Matching

Array Matching

Partial Matching

Test Structure Best Practices

AAA Pattern (Arrange-Act-Assert)

Nested describe for Organization

Common Mocking Patterns

Mocking SWR

Mocking Modules

Mocking Specific Functions

Integration Tests (with Database)

Testing Checklist

Running Tests

Summary: GROWI Testing Philosophy

Using `act()` and `waitFor()`

Nested `describe` for Organization