Mocking globals in Jest

Question

Is there any way in Jest to mock global objects, such as navigator, or Image*? I\'ve pretty much given up on this, and left it up to a series of mo

Answer 1

As every test suite run its own environment, you can mock globals by just overwriting them. All global variables can be accessed by the global namespace:

global.navigator = {
  onLine: true
}

The overwrite has only effects in your current test and will not effect others. This also a good way to handle Math.random or Date.now.

Note, that through some changes in jsdom it could be possible that you have to mock globals like this:

Object.defineProperty(globalObject, key, { value, writable: true });