Mock api calls from Storybook

Question

Does axios-mock-adapter only work on requests made with axios?

I have written a component that POSTs to an API (using vanilla XHR, not axios). I'm testing it in Storybook and want to intercept those POST requests since the endpoint doesn't exist yet:

import React from "react"
import { storiesOf } from "@kadira/storybook"
import MyComponent from "./MyComponent"
import axios from "axios"
import MockAdapter from "axios-mock-adapter"

var mock = new MockAdapter(axios)

storiesOf("My Component", module).addWithInfo(
  "Simulator",
  () => {
    mock.onPost().reply(500)
    return <MyComponent />
  },
  {}
)

My component still is trying to hit the API endpoint and I am getting a 404 response - not the expected 500 response.

Does axios-mock-adapter only work on requests made with axios? Does the mock call have to be inside MyComponent?

Thanks.