Problems with mocking mixins while testing vue app using jest

I faced with a problem that my component wrapper can't be initialized when the component being tested has mixins. When I comment it everything is fine.

This is my component wrapper with mixins mock which I use in tests:

beforeEach(() => {
    dealsSortingMixin = {
        methods: {
            sortUpBy: jest.fn(),
            sortDownBy: jest.fn()
        }
    }
    mixins = [
        dealsSortingMixin
    ]
    wrapper = shallow(Component, {
        localVue,
        store,
        filters,
        mixins,
        attachToDocument: true
    })
})

So, if the component being tested has mixins:

export default {
    ...
    mixins: [
        dealsSortingMixin
    ],
    ...
}

I have errors that the wrapper is undefined. If I comment mixins the wrapper is successfully initialized. What is the reason of it?