'A very basic test for the Header.update method--I\'d like to add a
few more cases to this at some point.'

def test_update_header_card(self):

    header = fits.Header()
    comment = 'number    of    bits    per    data    pixel'
    header['BITPIX'] = (16, comment)
    assert ('BITPIX' in header)
    assert (header['BITPIX'] == 16)
    assert (header.comments['BITPIX'] == comment)
    header.update(BITPIX=32)
    assert (header['BITPIX'] == 32)
    assert (header.comments['BITPIX'] == '')
