Testing

RNCopilot uses Jest 30 with jest-expo and @testing-library/react-native for component testing. This page covers test file location, patterns, and coverage targets.

Test File Location

Tests live next to the source files they test, not in a separate top-level test directory:


Button/
├── Button.tsx
├── Button.test.tsx    # Unit test
├── Button.styles.ts
├── Button.types.ts
└── index.ts

Feature-level integration tests go in a __tests__/ directory within the feature:


src/features/auth/
├── components/
├── hooks/
├── services/
├── __tests__/
│   └── authFlow.test.tsx    # Integration test
└── ...

Test Pattern

Use @testing-library/react-native for component tests. Follow the arrange-act-assert structure:


import { render, screen, fireEvent } from '@testing-library/react-native';
import { Button } from './Button';
 
describe('Button', () => {
  it('renders with title', () => {
    render(<Button title="Submit" onPress={jest.fn()} />);
    expect(screen.getByText('Submit')).toBeTruthy();
  });
 
  it('shows loading indicator when loading', () => {
    render(<Button title="Submit" loading onPress={jest.fn()} />);
    expect(screen.getByRole('button')).toHaveAccessibilityState({
      busy: true,
    });
  });
 
  it('calls onPress when pressed', () => {
    const onPress = jest.fn();
    render(<Button title="Submit" onPress={onPress} />);
    fireEvent.press(screen.getByRole('button'));
    expect(onPress).toHaveBeenCalledTimes(1);
  });
 
  it('does not call onPress when disabled', () => {
    const onPress = jest.fn();
    render(<Button title="Submit" onPress={onPress} disabled />);
    fireEvent.press(screen.getByRole('button'));
    expect(onPress).not.toHaveBeenCalled();
  });
});

Test Commands


# Run all tests
npm test
 
# Run tests with coverage report
npm run test:coverage
 
# Run a specific test file
npx jest src/common/components/Button/Button.test.tsx

Coverage Targets

Category	Target
Shared UI components (`src/common/components/`)	80%+
Feature services and hooks	70%+
Utility functions (`src/utils/`)	100%

These are targets, not hard gates. Aim to meet or exceed them for new code. Do not reduce coverage when modifying existing files.

What to Test

Components

Renders correctly with required props
Responds to user interaction (press, type, scroll)
Shows correct states (loading, disabled, error)
Accessibility roles and labels are present

Hooks

Returns correct initial state
Updates state in response to actions
Handles edge cases (empty data, errors)

Services

Returns expected data on success
Throws or returns error on failure
Passes correct parameters to the API client

Utilities

Every code path is covered
Edge cases and boundary values are tested
Error cases are tested

Testing Best Practices

Query by role or text rather than test IDs when possible.
Use screen from @testing-library/react-native instead of destructuring render().
Mock external dependencies (API, storage, navigation) at the module level.
Keep tests focused — one behavior per it() block.
Do not test implementation details (internal state, private methods).