Testing RxJS requests with nock

Say I had a function defined like so:

import {RxHR} from '@akanass/rx-http-request'
(arg) => RxHR.get(`https://third.party.com/${arg}`)
    .take(1)
    .pluck('body')
    .map(JSON.parse)

I now wish to test this function (call it importedFunction) say with mocha and nock, so I write a test, expecting it to be red so I can red green refactor:

describe('It makes the request', () => {
  before(() => {
    nock(`https://third.party.com`)
    .get(`/potato`)
    .reply(200, 'tomato')
  })

  it('makes the request', () => {
    return importedFunction(potato)
      .subscribe((response) => assert.equal(true, false))
    })

})

And my test passes (which it should not). So I add a console.log in my subscribe and it turns out my subscriber function is in fact not running.

How can I test an RxJS request? And why doesn't my implementation work?

via Abraham P