Test pollution while using TestBackend

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We're using the test backend and simulating dragging and dropping with the provided functions, simulateBeginDrag, simulateDrop, simulateDragEnd, etc. It becomes immediately apparent, however, that the same object is in effect across multiple tests, due to errors like cannot call beginDrag while dragging popping up only once a preceding test fails in the middle. Here's the code we're using to get the backend from our Component:

import { mount } from 'enzyme';
wrapper = mount(<MyComponent />)
backend = wrapper.instance().getManager().getBackend();

Are we using this wrong, is there a bad interaction with Enzyme, or is there legitimate test pollution going on here with static variables?