To unit test custom hooks in React, you can use tools like Jest and React Testing Library. Here's a step-by-step guide to unit testing custom hooks in React:
Create a test file for your custom hook: You can create a test file with a .test.js or .spec.js extension in the same directory as your custom hook.
Import the custom hook and any dependencies: In your test file, import the custom hook and any dependencies that are needed for testing.
Set up your test environment: You can set up your test environment by configuring Jest and any necessary mock functions or modules.
Write test cases for your custom hook: Write test cases to cover different scenarios and edge cases for your custom hook. You can use Jest's test or it functions to define individual test cases.
Use the custom hook in your test cases: Instantiate your custom hook in your test cases and test its functionality by calling it with different inputs and checking the expected output.
Mock any external dependencies: If your custom hook depends on external modules or functions, you can mock them using Jest's jest.mock function to isolate the testing of your custom hook.
Use assertions to validate the results: Use Jest's expect function to make assertions and validate the results of your custom hook. You can check for expected return values, side effects, or error conditions.
Run your test suite: You can run your test suite using Jest by running the npm test command or a custom script defined in your package.json file.
By following these steps, you can effectively unit test your custom hooks in React to ensure that they work as expected and handle different scenarios and edge cases.