Python: Replacing XML regtests with Python

It is fairly easy to translate an XML stsci regest into python. Here is an example.

An XML regtest:

<!--
##
## HEDIT - images/imutil/hedit: level 2
##  This test adds a new keyword to a header and compares the result to
## an image of expected results. Because the hedit task works on images
## in-place, a copy of the input image is created before running hedit,
## in order to preserve the original image.
##
-->

<RegTest>
<pre-exec>
   <command>import shutil</command>
   <command>shutil.copy('m51.fits', 'm51_test2.fits')</command>
</pre-exec>

<title>images/imutil/hedit: test 2</title>
<level>2</level>
<taskname>hedit</taskname>
<pfile>hedit_test2.par</pfile>
<output>
  <val>
    <file>m51_test2.fits</file>
    <reference>m51_test2_ref.fits</reference>
    <comparator>image</comparator>
    <ignorekeys>filename,date,iraf-tlm</ignorekeys>
  </val>
</output>

</RegTest>

Translate to python:

# To reproduce the regtest functionality, use these imports:

import pandokia.helpers.process as process
import pandokia.helpers.filecomp as filecomp


#
# The old xml tests contain a single test in a <regtest> block.
# We write that as a test in python.  The most convenient way to do
# it is as a test function.  This works with both nose and py.test
#

def test_2():

    # Even though the test is named after the test function, we
    # still need a string for the test name.  We use it later.
    testname = 'test_2'

    # You need to have a tda dict for:
    #  - recording information to make FlagOK work
    #  - recording parameters to the task as attributes
    global tda
    tda = { }

    # We use the same information from the <output> section, but
    # written as a python data structure instead of xml.
    #  <output>
    #    <val>
    #      <file>m51_test2.fits</file>
    #      <reference>m51_test2_ref.fits</reference>
    #      <comparator>image</comparator>
    #      <ignorekeys>filename,date,iraf-tlm</ignorekeys>
    #    </val>
    #  </output>

    output = [
            # one dict for each output file to compare (i.e. each <val>)
            {
                # copy file, reference, and comparator from the XML
                'file'      : 'm51_test2.fits',
                'reference' : 'm51_test2_ref.fits',
                'comparator': 'image',

                # any other XML fields in the <val> should be put in a
                # dict and stored in args:
                'args'      : {
                    # fitsdiff args ignorekeys and ignorecomm take
                    # a list instead of comma separated text
                    'ignorekeys': [ 'filename', 'date', 'iraf-tlm' ],
                    'maxdiff' : .0001,
                 },

            },
            # if there are more files, list more dicts here
        ]

    # delete all the output files before starting the test
    filecomp.delete_output_files( output )

    # for <pre-exec> and <post-exec>, just write the python commands
    # directly into your test
    #
    # <pre-exec>
    # <command>import shutil</command>
    # <command>shutil.copy('m51.fits', 'm51_test2.fits')</command>
    # </pre-exec>
    #
    import shutil
    shutil.copy('m51.fits', 'm51_test2.fits')

    # <title> and <level> don't count for anything in pandokia,
    # so ignore them

    # The old regtest runner loads the IRAF tasks for tables,
    # stsdas, images, and fitsio.  Load as many of the IRAF tasks
    # as you need.
    #
    # Skip this section if your test does not require pyraf/iraf.
    import pyraf        # not all tests need or want pyraf
    from pyraf.iraf import tables
    from pyraf.iraf import stsdas

    # for an IRAF task, use this helper function to run it
    #
    # <taskname>hedit</taskname>
    # <pfile>hedit_test2.par</pfile>
    #
    process.run_pyraf_task( 'hedit', 'hedit_test2.par', tda=tda )

    # If you have a post-exec, put the code here

    # compare the output files - use this exact command
    filecomp.compare_files( output, ( __file__, testname ), tda = tda,)