CODEWITHSUNDEEP
typescripttypescript-typingsvitest
Sławomir Ossowski
Sławomir Ossowski

Reputation: 84

Vitest mocking and conversion to <unknown>

in my code I have a factory method that produces an object based on injected dependencies:

const myFactory = (myRepository : Repository) => ({
    myMethod()  {
        return myRepository.repositoryMethod();
    }
})

then in my vitest test I want to mock myRepository when testing myFactory output:

const myRepositoryMock = <Repository><unknown>{
    repositoryMethod: vi.fn(),
}

describe('MyFactory test suite', () => {
    it('myMethod test', () => {

        const repositoryMethod = vi.spyOn(myRepositoryMock, 'repositoryMethod')
            .mockReturnValue({ foo: 'bar' })

        const myService = myFactory(myRepositoryMock);

        expect(myService.myMethod()).toStrictEqual({ foo: 'bar' });
        expect(repositoryMethod).toHaveBeenCalledOnce();
    });
});

so far, so good - it all works as expected, however what I don't like about this solution is temporary type conversion to unknown i.e.:

const myRepositoryMock = <Repository><unknown>{/* ... */}

I use it for readability. Basically Repository has lots of methods from which just one is relevant to this particular test and I do not want to have them all explicitly listed in my mock.

Do you know if/how can I get rid of <unknown> type conversion w/o having to add all methods specified in Repository type to myRepositoryMock?

Upvotes: 0

Views: 395

Answers (1)

Sławomir Ossowski
Sławomir Ossowski

Reputation: 84

it looks like an answer is:

const myRepositoryMock : Pick<Repository, "repositoryMethod"> = {/* ... */}

lmk if you come upon a better one.

Upvotes: 0

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