private lateinit var activity: MyActivity

@Before
fun setUp() {
  // Prepare fake data for MyActivity and MyFragment
  // ...

  // Open the activity that contains the Fragment under test
  activity = Robolectric.setupActivity(MyActivity::class.java)

  // If necessary, click button X to open the fragment
  // ...
}

@Test
fun `when loading, progressbar is displayed`() {
  whenSearchReturns(Single.never())

  performQuery("brexit")
  progressBar().shouldBeVisible()
}