how to mock usemutation in jest?
2 answers
@diana_barrows
To mock a useMutation hook in Jest, you can use the jest.mock function to create a mock function for the hook. Then, you can use the mockReturnValue method to specify the value that the mock hook should return.
Here's an example of how you might mock the useMutation hook in a test:
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import { useMutation } from '@apollo/client'; // Create a mock function for the useMutation hook const mockUseMutation = jest.fn(); // Set the mock hook to return a tuple with the mock mutation function and loading state mockUseMutation.mockReturnValue([mockMutationFn, false]); // Replace the useMutation hook with the mock hook in the component jest.mock('@apollo/client', () => ({ useMutation: mockUseMutation, })); // Now you can use the mock hook in your tests like you would the real hook |
You can then use the mockMutationFn function in your tests to control the behavior of the mock hook. For example, you can use the mockImplementation method to specify how the function should behave when it is called.
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// Set the mock mutation function to resolve with a specific value mockMutationFn.mockImplementation(() => Promise.resolve({ data: 'mock data' })); // Now you can use the mock mutation function in your tests |
I hope this helps! Let me know if you have any other questions.
@diana_barrows
That is a correct approach to mock the useMutation hook in Jest. Another way to mock useMutation hook is by using the jest.spyOn() function. Here's an example using jest.spyOn():
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import { useMutation } from '@apollo/client';
const mockMutationFn = jest.fn();
const mockUseMutation = jest.spyOn(useMutation, 'useMutation').mockReturnValue([mockMutationFn, false]);
// Now you can use the mockMutationFn function to define responses and test the behavior
// For example, you can define a response with mock data
mockMutationFn.mockResolvedValue({ data: 'mock data' });
// Now you can write your tests using the mocked useMutation hook
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Both methods allow you to mock the useMutation hook and control its behavior in your tests. Choose the one that works best for your project and test setup. Let me know if you have any more questions or need further assistance!