When it comes to building full-stack applications, authentication is a crucial aspect that needs to be thoroughly tested. In this article, we will discuss how to mock MongoDB's @realm/react library for testing authentication states with Jest.
Why Mock MongoDB's @realm/react?
When testing authentication states, it is important to isolate the authentication logic from the database operations. This is where mocking comes in. By mocking MongoDB's @realm/react library, we can simulate the behavior of the authentication logic without actually interacting with the database.
Setting up the Project
Before we begin, let's set up a new React project using create-react-app.
npx create-react-app my-app
cd my-app
Next, let's install the necessary dependencies.
npm install @realm/react jest @testing-library/react
Now that we have our project set up, let's create a simple authentication component using MongoDB's @realm/react library.
Creating the Authentication Component
Let's create a new file called Auth.js in the src directory.
touch src/Auth.js
Now, let's add the following code to Auth.js.
import React from 'react';
import { useAuth } from '@realm/react';
const Auth = () => {
const auth = useAuth();
if (auth.state === 'loading') {
return Loading...
;
}
if (auth.state === 'authenticated') {
return Welcome, {auth.user.profile.name}!
;
}
return (
);
};
export default Auth;
In this code, we are using MongoDB's useAuth() hook to access the authentication state and perform authentication operations.
Mocking MongoDB's @realm/react
Now that we have our authentication component set up, let's create a mock for MongoDB's @realm/react library. We will create a new file called __mocks__/@realm.js in the src directory.
mkdir src/__mocks__
touch src/__mocks__/@realm.js
Now, let's add the following code to src/__mocks__/@realm.js.
export const useAuth = () => {
let authState = 'unauthenticated';
let user = null;
const login = (userId, password) => {
authState = 'loading';
// Simulate a delay
setTimeout(() => {
authState = 'authenticated';
user = {
profile: {
name: 'Test User',
},
};
}, 2000);
};
const logout = () => {
authState = 'unauthenticated';
user = null;
};
return {
auth: {
state: authState,
user,
},
login,
logout,
};
};
In this code, we are creating a mock for MongoDB's useAuth() hook. We are simulating the authentication process and setting the authentication state to 'loading' for 2 seconds before setting it to 'authenticated'. We are also setting the user object to a mock user object with a name property.
Testing the Authentication Component
Now that we have our mock set up, let's write a test for our authentication component. We will create a new file called Auth.test.js in the src directory.
touch src/Auth.test.js
Now, let's add the following code to src/Auth.test.js.
import React from 'react';
import { render } from '@testing-library/react';
import { Provider } from 'react-redux';
import { createStore } from 'redux';
import Auth from './Auth';
import { useAuth } from '@realm/react';
jest.mock('@realm/react', () => ({
useAuth: jest.fn(),
}));
const renderWithAuth = (component) => {
const store = createStore(() => {});
useAuth.mockReturnValue({
auth: {
state: 'unauthenticated',
user: null,
},
login: jest.fn(),
logout: jest.fn(),
});
return {
store,
...render(
{component}
),
};
};
test('renders loading state when authentication state is loading', () => {
const { getByText } = renderWithAuth(
In this code, we are using Jest's mockReturnValue() function to mock the authentication state and user object. We are also using Jest's jest.mock() function to mock MongoDB's useAuth() hook. We are then using renderWithAuth() function to render the authentication component with the mocked authentication state and user object.
We are then writing tests for different authentication states and simulating user interactions. We are also checking if the authentication functions are called with the correct parameters.
In this article, we discussed how to mock MongoDB's @realm/react library for testing authentication states with Jest. We created a mock for MongoDB's useAuth() hook and wrote tests for different authentication states. By mocking MongoDB's @realm/react library, we can simulate the behavior of the authentication logic without actually interacting with the database.
References
| Reference | Description |
|---|---|
| MongoDB Realm SDK for React | Documentation for MongoDB Realm SDK for React |
| Jest Mock Functions | Documentation for Jest Mock Functions |
| Jest Mock Modules | Documentation for Jest Mock Modules |
| React Testing Recipes - Mocking Modules | Documentation for React Testing Recipes - Mocking Modules |