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Tag: mocking

How to mock instance methods of a class mocked with jest.mock?

How can the instance methods be mocked for a class that is being mocked with jest.mock? For example, a class Logger is mocked: Answer Automatic Mocking Calling jest.mock automatically mocks all the exports from the module being mocked unless a manual mock is specified using the __mocks__ directory. So, this line jest.mock(“./Logger”) has automatically replaced the Logger constructor and all

Testing window.location in jest

I am trying to test the window functionality via jest. I have a function which appends a query param to the url and redirects the page to the other page. A rough snippet of the code is below: I am new to jest and I am facing a bit of difficulty simulating the mock test for this, hence can you

Using Spies and Mocks on complex objects with Jest

I’m fairly new to testing and writing tests for a currently uncovered javaScript codebase using Jest. The code covers some niche use cases, as its conditionally injected and executed by the browser during page load. Anyway, I’m having issues mocking up custom objects. Here’s the function in question: As far as I understand, I need […]

How to return based on actual arguments being sent?

Let’s say we have a function with two arguments. It’s being called many times with different arguments on every call. So, its impossible to stub it with withArgs option. I want to write a stub function which will check the actual arguments being passed (args1, args2) and return a static response with a switch case. Something on the following lines:

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