Test Nextjs <Link /> with Jest + Testing-Library

When I'm testing the <Link /> behavior, expecting it to redirect to a certain route, there's a TypeError (Cannot read property 'push' of null).

This is the component I'm currently testing:

import React from "react"
import Link from "next/link"

const Sandbox = () => {
  return (
    <div>
      <Link href="/about">
        <a data-testid="mytest">Click Me</a>
      </Link>
    </div>
  )
}

export default Sandbox

And this is the test I'm running:

import React from "react"
import { render, fireEvent } from "@testing-library/react"
import { useRouter } from "next/router"
import Sandbox from ".."

jest.mock("next/router", () => ({
  useRouter: jest.fn(),
}))

describe("Sandbox", () => {
  it.only("should navigate accordingly", () => {
    const push = jest.fn()
    useRouter.mockImplementationOnce(() => ({
      asPath: "/",
      push,
    }))

    const { getByTestId } = render(<Sandbox />)

    const mytest = getByTestId("mytest")
    fireEvent.click(mytest)
    expect(push).toHaveBeenCalledWith("/about")
  })
})

I believe that I've mocked everything I need, so I don't really understand why the router can't actually "push". What am I missing here?