make results_test.py work better within python unittest framework

gm/rebaseline_server/results_test.py

 #!/usr/bin/python
 
 """
 Copyright 2013 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 Test results.py
 
 TODO(epoger): Launch this (and other unittests within this dir) automatically
 on the housekeeper bot, but first make sure it works properly after having been
 checked out (from both git and svn)
 
 TODO(epoger): Create a command to update the expected results (in
-OUTPUT_DIR_EXPECTATIONS) when appropriate.  For now, you should:
-1. examine the results in OUTPUT_DIR and make sure they are ok
-2. rm -rf OUTPUT_DIR_EXPECTATIONS
-3. mv OUTPUT_DIR OUTPUT_DIR_EXPECTATIONS
+OUTPUT_DIR_EXPECTED) when appropriate.  For now, you should:
+1. examine the results in OUTPUT_DIR_ACTUAL and make sure they are ok
+2. rm -rf OUTPUT_DIR_EXPECTED
+3. mv OUTPUT_DIR_ACTUAL OUTPUT_DIR_EXPECTED
 Although, if you're using an SVN checkout, this will blow away .svn directories
-within OUTPUT_DIR_EXPECTATIONS, which wouldn't be good...
+within OUTPUT_DIR_EXPECTED, which wouldn't be good...
 
 """
 
 import filecmp
 import os
 import shutil
 import sys
 import tempfile
 import unittest
 
 # Imports from within Skia
 import results
 import gm_json  # must import results first, so that gm_json will be in sys.path
 
 PARENT_DIR = os.path.dirname(os.path.realpath(__file__))
 INPUT_DIR = os.path.join(PARENT_DIR, 'tests', 'inputs')
-OUTPUT_DIR = os.path.join(PARENT_DIR, 'tests', 'outputs', 'actual')
-OUTPUT_DIR_EXPECTATIONS = os.path.join(
-    PARENT_DIR, 'tests', 'outputs', 'expected')
+OUTPUT_DIR_ACTUAL   = os.path.join(PARENT_DIR, 'tests', 'outputs', 'actual')
+OUTPUT_DIR_EXPECTED = os.path.join(PARENT_DIR, 'tests', 'outputs', 'expected')
+
 
 class ResultsTest(unittest.TestCase):
 
   def setUp(self):
-    self._tempdir = tempfile.mkdtemp()
+    self._temp_dir = tempfile.mkdtemp()
+    self._output_dir_actual   = os.path.join(OUTPUT_DIR_ACTUAL, self.id())
+    self._output_dir_expected = os.path.join(OUTPUT_DIR_EXPECTED, self.id())
+    create_empty_dir(self._output_dir_actual)
 
   def tearDown(self):
-    shutil.rmtree(self._tempdir)
+    shutil.rmtree(self._temp_dir)
+    different_files = find_different_files(self._output_dir_actual,
+                                           self._output_dir_expected)
+    assert (not different_files), \

[rmistry, 2014/01/03 15:18:42]

I find it slightly strange to see an assert in tearDown, but maybe that is ok.

[epoger, 2014/01/03 15:42:07]

Good point.  Added a comment explaining the situation.  Maybe we'll come up with
a better way.

[rmistry, 2014/01/03 15:44:18]

Also another minor reason to not have it here: if somebody later comes along and
adds cleanup code below the assert then if tests fail the artifacts will not be
cleaned up.
This is not major, we can come up with a better solution later.

[epoger, 2014/01/03 15:48:09]

Good point again.  Added that to my explanatory comment.

+      ('found differing files between actual dir %s and expected dir %s: %s' %
+       (self._output_dir_actual, self._output_dir_expected, different_files))
 
   def test_gm(self):
     """Process results of a GM run with the Results object."""
     results_obj = results.Results(
         actuals_root=os.path.join(INPUT_DIR, 'gm-actuals'),
         expected_root=os.path.join(INPUT_DIR, 'gm-expectations'),
-        generated_images_root=self._tempdir)
+        generated_images_root=self._temp_dir)
     gm_json.WriteToFile(results_obj.get_results_of_type(results.RESULTS_ALL),
-                        os.path.join(OUTPUT_DIR, 'gm.json'))
+                        os.path.join(self._output_dir_actual, 'gm.json'))
 
 
+def create_empty_dir(path):
+  """Create an empty directory at the given path."""
+  if os.path.isdir(path):
+    shutil.rmtree(path)
+  elif os.path.lexists(path):
+    os.remove(path)
+  os.makedirs(path)
+

[rmistry, 2014/01/03 15:18:42]

Nit: Add one more newline here.

[epoger, 2014/01/03 15:42:07]

Done.

 def find_different_files(dir1, dir2, ignore_subtree_names=None):
   """Returns a list of any files that differ between the directory trees rooted
   at dir1 and dir2.
 
   Args:
     dir1: root of a directory tree; if nonexistent, will raise OSError
     dir2: root of another directory tree; if nonexistent, will raise OSError
     ignore_subtree_names: list of subtree directory names to ignore;
           defaults to ['.svn'], so all SVN files are ignores
 
   TODO(epoger): include the dirname within each filename (not just the
   basename), to make it easier to locate any differences
   """
   differing_files = []
   if ignore_subtree_names is None:
     ignore_subtree_names = ['.svn']
   dircmp = filecmp.dircmp(dir1, dir2, ignore=ignore_subtree_names)
   differing_files.extend(dircmp.left_only)
   differing_files.extend(dircmp.right_only)
   differing_files.extend(dircmp.common_funny)
   differing_files.extend(dircmp.diff_files)
   differing_files.extend(dircmp.funny_files)
   for common_dir in dircmp.common_dirs:
     differing_files.extend(find_different_files(
         os.path.join(dir1, common_dir), os.path.join(dir2, common_dir)))
   return differing_files
 
 
 def main():
-  if not os.path.isdir(OUTPUT_DIR):

[epoger, 2014/01/02 21:24:08]

Moving all the pre- and post-test steps into setUp() and tearDown() allows us to
launch this unittest automatically in the standard Python unittest way:

epoger@wpgntat-ubiq141:~/src/skia/red/skia$ python -m unittest discover
--start-directory=gm/rebaseline_server --pattern='*_test.py' --verbose
test_gm (results_test.ResultsTest)
Process results of a GM run with the Results object. ... ok

----------------------------------------------------------------------
Ran 1 test in 0.833s

OK

-    os.makedirs(OUTPUT_DIR)
   suite = unittest.TestLoader().loadTestsFromTestCase(ResultsTest)
   unittest.TextTestRunner(verbosity=2).run(suite)
-  different_files = find_different_files(OUTPUT_DIR, OUTPUT_DIR_EXPECTATIONS)
-  assert (not different_files), 'found differing files: %s' % different_files
 
 
 if __name__ == '__main__':
   main()