Blog Post 7: Testing Our TypeScript React Application
Welcome back, developers! In our previous post, we enhanced the UI of our POS system with CSS Modules and animations. Today, we’ll focus on adding unit tests to our TypeScript components and context. Testing is a crucial part of building robust and maintainable applications, and TypeScript provides excellent tools for writing type-safe tests.
We’ll be using Jest as our test runner and React Testing Library for testing our React components. If you haven’t already set these up in your project, you can install them with:
npm install — save-dev jest @types/jest @testing-library/react @testing-library/jest-dom
Let’s start by writing tests for our POS context:
import React from 'react';
import { render, act } from '@testing-library/react';
import { POSProvider, usePOS } from '../context/POSContext';
import { MenuItem } from '../context/types';
// Mock the API service
jest.mock('../apiService', () => ({
fetchMenuItems: jest.fn().mockResolvedValue([
{ id: 1, name: 'Burger', price: 10, category: 'Main' },
{ id: 2, name: 'Fries', price: 5, category: 'Side' },
]),
processPayment: jest.fn().mockResolvedValue({ success: true, transactionId: '123' }),
}));
const TestComponent: React.FC = () => {
const { state, addToOrder } = usePOS();
return (
<div>
<div data-testid="menu-count">{state.menu.length}</div>
<div data-testid="order-count">{state.currentOrder?.items.length || 0}</div>
<button onClick={() => addToOrder(state.menu[0])}>Add to…