How to mock react-router context

Thanks @Elon Szopos for your answer but I manage to write something much more simple (following https://github.com/airbnb/enzyme/pull/62):

import NavLink from '../index';

import expect from 'expect';
import { shallow } from 'enzyme';
import React from 'react';

describe('<NavLink />', () => {
  it('should add active class', () => {
    const context = { router: { isActive: (a, b) => true } };
    const renderedComponent = shallow(<NavLink to="/home" />, { context });
    expect(renderedComponent.hasClass('active')).toEqual(true);
  });
});

I have to change mount to shallow in order not to evaluate Link which gives me an error connected with the react-router TypeError: router.createHref is not a function.

I would rather have “real” react-router than just an object but I have no idea how to create it.