i need to cover my code with some unit tests and in one of then i have the following situation.
app.tsx
async someMethod( . . . window.location.replace(sessionStorage.getItem(REDIRECT_VALUE)); . . . )
and in my test file
window.location.replace = jest.fn(); . . somevariable.SomeMethod = jest.fn(); expect(window.location.replace).toHaveBeenCalledWith("some url to redirect on");
i’m getting the followein error : Cannot assign to read only property ‘replace’ of object ‘[object Location]’
i’ve tried other aproachs like
backupState = window.location delete window.location; window.location = Object.assign(new URL("https://example.org"), { ancestorOrigins: "", replace: jest.fn() });
});
but i get different erros for each one of them, is there another way of doing it?
Previously i was using :
history.location.push(sessionStorage.getItem(REDIRECT_VALUE));
and
expect(auth.history.push).toHaveBeenCalled();
and in that case the test went OK.
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Answer
One way to test it is:
Create a mock function to location.replace
:
const replaceMock = jest.fn();
And spyOn window
, replacing location object and setting the replaceMock
to replace.
Complete test example:
const replaceMock = jest.fn(); describe('replace Location test ', () => { it('should call location with specific arg', () => { jest.spyOn(global as any, 'window', 'get').mockImplementationOnce(() => ({ location: { replace: replaceMock, }, })); someMethod(); expect(replaceMock).toBeCalledWith('XX Value you want to test XX'); }); });