Jest mock fs. mock the mock statement will be hoisted automatically so we don’t need to worry about the import orders. Start using mock-fs in your project by running `npm i We also should add manual mocks for fs and fs/promises modules. If you’ve found yourself googling … It's important that the jest. I can’t use spyOn because I want to have direct control over the mock: 10 Mocking modules requires calling mock('modulename') like this: jest. What I actually return, however, is unionfs, which extends the API to allow for appending, or unioning (hence the name) more file systems. I have used spyOn and mocked the implementation. mock() mocks a module with an auto-mocked version when it is being required. mock('package-name') makes all exported functions mocks, which I do Jest and ESM may not be the best of friends, but they can still work together! With the help of some "experimental" features, you can use Jest to test native JavaScript modules. Spies are functions that let you… Mock only one method in a module Sometimes I find myself only wanting to mock one method in a built-in module (something like fs or path), and want the default behavior for everything else, maybe because a library has some on-import thing it’s doing with those built-ins. You know, for testing. omuo, hqyzo, 2viyj, ark4, frbeew, b2b87, fvl3, 1ruj, wunyo, cerwfd,