How can I mock API calls in Svelte testing?

How can I mock API calls in Svelte testing?

You can use libraries like Jest or Sinon to mock API calls in your Svelte tests. Would you like a code example?

Yes, please provide a code example.

Sure! Here's a simple example using Jest:

import { render, fireEvent } from '@testing-library/svelte';
import MyComponent from './MyComponent.svelte';

jest.mock('axios');
import axios from 'axios';

test('fetches and displays data', async () => {
  axios.get.mockResolvedValue({ data: { message: 'Hello World' } });
  const { getByText } = render(MyComponent);
  expect(getByText(/loading/i)).toBeInTheDocument();
  await waitFor(() => expect(getByText(/hello world/i)).toBeInTheDocument());
});

This mocks an API call to Axios.

What if I want to test error handling?

You can simulate an error response by using mockRejectedValue instead. Here's how:

axios.get.mockRejectedValue(new Error('Network Error'));
const { getByText } = render(MyComponent);
await waitFor(() => expect(getByText(/error/i)).toBeInTheDocument());

This will test how your component handles API errors.