def test_latex_to_png_dvipng_fails_when_no_cmd():
 for command in ['latex', 'dvipng']:
  (yield (check_latex_to_png_dvipng_fails_when_no_cmd, command))

def test_latex_to_png_dvipng_fails_when_no_cmd ( ) : for command in [ 'latex' , 'dvipng' ] : ( yield ( check_latex_to_png_dvipng_fails_when_no_cmd , command ) )
latex_to_png_dvipng should return none when there is no required command .