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javascriptunit-testingtddjestjs

Jest: how to mock console when it is used by a third-party-library?

I am trying to mock console.warn/error but I can't. I use a third-party-library which calls console.warn inside it. I need to test was it called or wasn't. In my test case I was trying to stub console.warn but it didn't help. After that I was trying to mock console manually it didn't work out either.

console.warn = jest.fn();
testSchema('/app/components/Users/UserItem/UserItemContainer.js');
expect(console.warn).toBeCalled();

didn't work

console.warn = jest.fn();
testSchema('/app/components/Users/UserItem/UserItemContainer.js');
console.warn('error');
expect(console.warn).toBeCalled();

did work.

But I still see console.warn node_modules/babel-relay-plugin/lib/getBabelRelayPlugin.js:138 in the terminal.

Solution

  • You have to use global to access objects in the global context

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

    or use jest.spyOn added in 19.0.0

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