new_contents: import numpy as np
  
  
  def test_astrom_manager():
      # I was having a pretty hard time in coming
      # up with a unit test only testing the get_astrom function
      # that would not just test its implementation with its implementation
      # so we test a coordinate conversion using it
  
      from astropy.coordinates.astrom_manager import astrom_interpolation_resolution
      from astropy.coordinates import SkyCoord, EarthLocation, AltAz
      from astropy.time import Time
      import astropy.units as u
  
      location = EarthLocation(
          lon=-17.891105 * u.deg,
          lat=28.761584 * u.deg,
          height=2200 * u.m,
      )
      obstime = Time('2020-01-01T18:00') + np.linspace(0, 12, 1000) * u.hour
  
      altaz = AltAz(location=location, obstime=obstime)
      coord = SkyCoord(ra=83.63308333, dec=22.0145, unit=u.deg)
  
      # do the reference transformation, no interpolation
      ref = coord.transform_to(altaz)
  
      with astrom_interpolation_resolution.set(300 * u.s):
          interp_300s = coord.transform_to(altaz)
  
      # make sure they are actually different
      assert np.any(ref.separation(interp_300s) > u.Quantity(0.01, u.microarcsecond))
  
      # make sure the resolution is as good as we expect
      assert np.all(ref.separation(interp_300s) < u.Quantity(1, u.microarcsecond))
  
  
  def test_interpolation_2d():
      # I was having a pretty hard time in coming
      # up with a unit test only testing the get_astrom function
      # that would not just test its implementation with its implementation
      # so we test a coordinate conversion using it
  
      from astropy.coordinates.astrom_manager import get_astrom
  
      from astropy.coordinates import EarthLocation, AltAz, GCRS
      from astropy.time import Time
      import astropy.units as u
  
      location = EarthLocation(
          lon=-17.891105 * u.deg,
          lat=28.761584 * u.deg,
          height=2200 * u.m,
      )
      obstime = Time('2020-01-01T18:00') + np.linspace(0, 12, 1000) * u.hour
      obstime = obstime.reshape((25, 40))
  
      altaz = AltAz(location=location, obstime=obstime)
      gcrs = GCRS(obstime=obstime)
  
      for frame, tcode in zip([altaz, altaz, gcrs], ['apio13', 'apci', 'apcs']):
          without_interp = get_astrom(frame, tcode, interpolation_resolution=0 * u.s)
  
          with_interp = get_astrom(frame, tcode)
          assert without_interp.shape == with_interp.shape
  
subject: Add tests for interpolation