component.test.js

import React from "react";
import Button from "Button";
import { mountWrap } from 'contextWrap';

describe("Given the button is rendered with just a label", () => {

    const data = {
        label: "My Button"
    }
    let wrapper, aElement;

    beforeEach(()=>{
        wrapper = mountWrap(
            <Button
                label={data.label}
              />)
        aElement = wrapper.find('button');
    })

    it('has one span and is populated correctly', () => {
        expect(aElement).toHaveLength(1);
        expect(aElement.hasClass('btn')).toBeTruthy();
    });
});

contentWrap.js

import { BrowserRouter } from 'react-router-dom';
import { mount } from 'enzyme';
import { shape } from 'prop-types';

const router = {
    history: new BrowserRouter().history,
    route: {
        location: {},
        match: {},
    },
};

const createContext = () => ({
    context: { router },
    childContextTypes: { router: shape({}) },
});

export function mountWrap(node) {
    return mount(node, createContext());
}