Is it ok to use initialState as stub for reducer tests importing it from reducer itself?

foo.test.js

// Is it ok to use initialState as stub for reducer tests importing it from reducer itself?

import { initialState, fooReducer } from './reducers/foo';

var reducedState = { ... initialState }
reducedState.name = 'bar';

expect(fooReducer(initialState)).to.eql(reducedState);

foo.test.v2.js

// Here is different approach

import { fooReducer } from './reducers/foo';

var initialState = { foo: 'bar' };
var reducedState = { ... initialState }
reducedState.name = 'bar';

expect(fooReducer(initialState)).to.eql(reducedState);