Sometimes, we want to mock console when it is used by a third-party library with Jest.

In this article, we’ll look at how to mock console when it is used by a third-party library with Jest.

How to mock console when it is used by a third-party library with Jest?

To mock console when it is used by a third-party library with Jest, we can set the global.console property to our own mock object.

For instance, we write:

global.console = {
  warn: jest.fn()
}
expect(console.warn).toBeCalled()

to set global.console to an object that mocks the console.warn method by setting warn to jest.fn.

Then we check that console.warn is called with expect(console.warn).toBeCalled().

We can also use jest.spyOn to mock console.warn with

jest.spyOn(global.console, 'warn')

since Jest 19.0.0.

Conclusion

To mock console when it is used by a third-party library with Jest, we can set the global.console property to our own mock object.