[Tutor] Better printing?

[Steve Nelson]

Hello,

See below a program that will go through a directory and for each file
print user, group, size and md5sum.

A few questions:

1) It seems to fall over if I pass "." as a directory - how can I stop this?
2) When I wrote the methods I decided to do isafile() checks there,
but subsequently realised that in __main__ it would print out None for
each non-file, so I put the check in here too.  Which is better?  Or
is there a better approach?
3) How can I get this to print in a format that makes it easy to read?
ie tabulated so that the info is presented in aligned columns?

Code follows:

#!/usr/bin/env python

# Standard library imports

import unittest, os, sys, pwd, grp, md5

# Global defines

wp = sys.argv[1]

# Exception classes

# Utility functions

def getSize(fn):
  """Get the size of a file in kb"""
  fp = os.path.join(wp, fn)
  if os.path.isfile(fp):
    return os.stat(fp).st_size

def getUser(fn):
  """Get username of file owner."""
  fp = os.path.join(wp, fn)
  if os.path.isfile(fp):
    uid = os.stat(fp).st_uid
    return pwd.getpwuid(uid).pw_name

def getGroup(fn):
  """Get the group name of the file owner."""
  fp = os.path.join(wp, fn)
  if os.path.isfile(fp):
    gid = os.stat(fp).st_gid
    return grp.getgrgid(gid).gr_name

def md5Sum(fn):
  """Get md5sum for a file."""
  fp = os.path.join(wp, fn)
  if os.path.isfile(fp):
    try:
      fo = open(fp, 'rb')
    except (IOError, OSError):
      print "Could not open file '%s', skipping..." % fp
      return None
    else:
      m = md5.new(fo.read()).hexdigest()
      fo.close()
    return m

# Classes

# Unit tests

class UnitTests(unittest.TestCase):
  """Do not taunt unit tests."""

  def testGetSize(self):
    """Get the size of a file in kb"""
    self.assertEqual(getSize("foo"), 24)

  def testGetUser(self):
    """Get the username of the file owner"""
    self.assertEqual(getUser("foo"), "nelsonst")

  def testGetGroup(self):
    """Get the group name of the file owner"""
    self.assertEqual(getGroup("foo"), "staff")

  def testMd5Sum(self):
    """Get md5sum for file."""
    self.assertEqual(md5Sum("foo"), "faac88479f39ba498e827622a2a4d649")

def doTests():
  suite = unittest.makeSuite(UnitTests,'test')
  runner = unittest.TextTestRunner()
  result = runner.run(suite)

if __name__ == "__main__":
  doTests()
  for f in os.listdir(wp):
    if os.path.isfile(os.path.join(wp, f)):
      print f, getSize(f), getUser(f), getGroup(f), md5Sum(f)