getting " No QueryClient set, use QueryClientProvider to set one " when testing a react query component with react testing library

2 min read 05-10-2024

getting " No QueryClient set, use QueryClientProvider to set one " when testing a react query component with react testing library

Conquering the "No QueryClient set" Error in React Query Testing

React Query is a powerful library for fetching, caching, and managing data in React applications. However, when testing React Query components with tools like React Testing Library, you might encounter the dreaded "No QueryClient set, use QueryClientProvider to set one" error. This article will break down the root cause of this error and guide you through the process of successfully testing your React Query components.

Understanding the Error

This error arises when you try to interact with React Query functionalities like useQuery or useMutation within your test environment. The problem is that React Query needs a QueryClient instance to function correctly. In a regular React application, this QueryClient is typically set up using the QueryClientProvider component, which ensures its availability throughout your app. However, when testing, this setup isn't automatically present.

Scenario and Original Code

Let's consider a simple scenario where you have a component MyComponent that fetches data using React Query:

import { useQuery } from 'react-query';

const MyComponent = () => {
  const { data, isLoading, error } = useQuery('myData', () => fetch('/api/data').then(res => res.json()));

  // ... render logic based on data, isLoading, and error

  return (
    <div>
      {isLoading && <p>Loading...</p>}
      {error && <p>Error: {error.message}</p>}
      {data && <p>Data: {data.name}</p>}
    </div>
  );
};

export default MyComponent;

Now, if you try to render and test this component using React Testing Library without setting up a QueryClient, you'll hit the "No QueryClient set" error.

The Solution: Providing a QueryClient

The key to overcoming this error is to explicitly provide a QueryClient instance within your test environment. Here's how to do it:

Import the necessary modules:

import { render, screen, fireEvent } from '@testing-library/react';
import { QueryClient, QueryClientProvider } from 'react-query';
import MyComponent from './MyComponent';

Create a QueryClient instance:
```
const queryClient = new QueryClient();
```

Wrap your component with the QueryClientProvider:

render(
  <QueryClientProvider client={queryClient}>
    <MyComponent />
  </QueryClientProvider>
);

Now, when you run your tests, React Query will have access to the QueryClient instance and your component will function as expected.

Additional Considerations

Mocking API Requests: In your tests, you'll likely want to mock the API requests to ensure predictable results. You can use tools like jest-fetch-mock or msw to achieve this.
Testing Query State: After setting up a QueryClient, you can test different states of your React Query component, such as loading, success, and error. Use the queryClient.getQueryData and queryClient.setQueryData methods to manipulate the data and test various scenarios.
Cleanup: After each test, it's good practice to reset the QueryClient to its default state using queryClient.clear() to prevent interference in subsequent tests.

Conclusion

By understanding the role of the QueryClient and providing it within your test environment, you can effectively test React Query components with React Testing Library. Remember to mock API requests and manipulate query data for comprehensive testing. This approach will help you build reliable and well-tested React applications that utilize the power of React Query.