old_contents: from ..io import class_lmv, fits
  from .. import SpectralCube
  from . import path
  import pytest
  
  def test_lmv_fits():
      c1 = SpectralCube.read(path('example_cube.fits'))
      c2 = SpectralCube.read(path('example_cube.lmv'))
  
      assert c1.shape == c2.shape
  
      # should be able to do this, but it is not true:
      #assert c1.header == c2.header
  
      # should also be able to do this, but it is again false:
      #assert c1.wcs==c2.wcs
  
new_contents: from astropy.io import fits as pyfits
  from ..io import class_lmv, fits
  from .. import SpectralCube
  from . import path
  import pytest
  
  def test_lmv_fits():
      c1 = SpectralCube.read(path('example_cube.fits'))
      c2 = SpectralCube.read(path('example_cube.lmv'))
  
      assert c1.shape == c2.shape
  
      # should be able to do this, but it is not true:
      #assert c1.header == c2.header
  
      # should also be able to do this, but it is again false:
      #assert c1.wcs==c2.wcs
  
  def test_3d_4d_stokes():
      f3 = pyfits.open(path('adv.fits'))
      f4 = pyfits.open(path('advs.fits'))
      f3b = pyfits.PrimaryHDU(data=f3[0].data, header=f4[0].header)
  
      c1 = SpectralCube.read(f3)
      c2 = SpectralCube.read(f4)
      c3 = SpectralCube.read(f3b)
  
      assert c1.shape == c3.shape
      # c2 has a different shape on disk...
  
subject: add a test for the new 3d/4d checker