How to mock window.location.href with Jest + Vuejs?

You can try:

global.window = Object.create(window);
const url = "http://dummy.com";
Object.defineProperty(window, 'location', {
  value: {
    href: url
  }
});
expect(window.location.href).toEqual(url);  

Have a look at the Jest Issue for that problem:
Jest Issue