A way of parsing unix command output

unix_command_to_python.py

import unittest
from mock import patch
import subprocess
import csv


class UnixCommandParser(object):

    def ls_l(self, directory="."):
        self.command = ['ls', '-l', directory]
        self.delimiter = ' '
        self.skipinitialspace = True
        self.skipinitiallines = 1

        self.fieldnames = ['permissions', 'links',
                           'owner', 'group', 'size',
                           'month',
                           'date', 'time', 'name']
        return self._parse()

    def ls(self, directory="."):
        self.command = ['ls', directory]
        self.delimiter = ' '
        self.skipinitialspace = True
        self.skipinitiallines = 1

        self.fieldnames = ['name']
        return self._parse()

    def _run_command(self):
        return subprocess.Popen(self.command, stdout=subprocess.PIPE).communicate()

    def _get_stdout_reader(self, stdout, skip_lines=0):
        return \
    csv.DictReader(stdout.decode('ascii').splitlines()[self.skipinitiallines:],
                              delimiter=self.delimiter,
                              skipinitialspace=self.skipinitialspace,
                              fieldnames=self.fieldnames)

    def _parse(self, skip_lines=0):
        stdout, stderr = self._run_command()
        output = [row for row in self._get_stdout_reader(stdout)]
        return output

class TestUnixCommandParser(unittest.TestCase):
    """ Test that Commands are parsed successfully by the parser. """

    def test_ls_l(self):
        """ ls -l """
        fieldnames = ['permissions', 'links',
                      'owner', 'group', 'size',
                      'month',
                      'date', 'time', 'name']
        raw_ls_l_output = \
"""total 752
-rw-rw-r-- 1 svnmirror subversion  3925 Jun 25 15:23 BUG_EXAMPLES.md
-rw-rw-r-- 1 svnmirror subversion 1210 Jul 16 08:29 code_under_test.py
-rw-rw-r-- 1 svnmirror subversion 2040 Jul 15 10:28 code_under_test.pyc"""

        list_ls_l_output = [["-rw-rw-r--", "1", "svnmirror", "subversion", \
                "3925", "Jun", "25", "15:23", "BUG_EXAMPLES.md"],
                ["-rw-rw-r--", "1", "svnmirror", "subversion", \
                        "1210", "Jul", "16", "08:29", "code_under_test.py"],
                ["-rw-rw-r--", "1", "svnmirror", "subversion", \
                        "2040", "Jul", "15", "10:28", "code_under_test.pyc"]]

        expected_output = [dict(zip(fieldnames, line)) \
                for line in list_ls_l_output]

        with patch('subprocess.Popen') as mock_popen:
            instance = mock_popen()
            instance.communicate.return_value = [raw_ls_l_output, "foo"]
            parser = UnixCommandParser()
            output = parser.ls_l()
            self.assertEquals(output, expected_output)

def main():
    unittest.main()

if __name__ == '__main__':
    main()