combine base_unittest.py modules from gm and tools

tools/tests/base_unittest.py

 #!/usr/bin/python
 
 """
 Copyright 2014 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 
 A wrapper around the standard Python unittest library, adding features we need
 for various unittests within this directory.
+
+TODO(epoger): Move this into the common repo for broader use?  Or at least in

[epoger, 2014/07/16 20:05:45]

As noted here, I would like to move the real base_unittest.py into a more common
directory (perhaps within the common repo???)  Then tools/tests/base_unittest.py
will become a thin wrapper around the real base_unittest.py, just like
gm/rebaseline_server/base_unittest.py is now.

But in the meanwhile, I wanted to start by combining the files, rather than
continuing to maintain multiple copies of base_unittest.py in parallel.

+a more common place within the Skia repo?
 """
 
 import errno
+import filecmp
 import os
 import shutil
-import sys
+import tempfile
 import unittest
 
-# Set the PYTHONPATH to include the tools directory.
-sys.path.append(
-    os.path.join(os.path.dirname(os.path.realpath(__file__)), os.pardir))
-import find_run_binary
+TRUNK_DIR = os.path.abspath(os.path.join(
+    os.path.dirname(__file__), os.pardir, os.pardir))
 
 
 class TestCase(unittest.TestCase):
 
+  def __init__(self, *args, **kwargs):
+    super(TestCase, self).__init__(*args, **kwargs)
+    # Subclasses should override this default value if they want their output
+    # to be automatically compared against expectations (see setUp and tearDown)
+    self._testdata_dir = None
+
+  def setUp(self):
+    """Called before each test."""
+    # Get the name of this test, in such a way that it will be consistent
+    # regardless of the directory it is run from (throw away package names,
+    # if any).
+    self._test_name = '.'.join(self.id().split('.')[-3:])
+
+    self._temp_dir = tempfile.mkdtemp()
+    if self._testdata_dir:
+      self.create_empty_dir(self.output_dir_actual)
+
+  def tearDown(self):
+    """Called after each test."""
+    shutil.rmtree(self._temp_dir)
+    if self._testdata_dir and os.path.exists(self.output_dir_expected):
+      different_files = _find_different_files(self.output_dir_actual,
+                                              self.output_dir_expected)
+      # Don't add any cleanup code below this assert!
+      # Then if tests fail, the artifacts will not be cleaned up.
+      assert (not different_files), \
+        ('found differing files:\n' +
+         '\n'.join(['tkdiff %s %s &' % (
+             os.path.join(self.output_dir_actual, basename),
+             os.path.join(self.output_dir_expected, basename))
+                    for basename in different_files]))
+
+  @property
+  def temp_dir(self):
+    return self._temp_dir
+
+  @property
+  def input_dir(self):
+    assert self._testdata_dir, 'self._testdata_dir must be set'
+    return os.path.join(self._testdata_dir, 'inputs')
+
+  @property
+  def output_dir_actual(self):
+    assert self._testdata_dir, 'self._testdata_dir must be set'
+    return os.path.join(
+        self._testdata_dir, 'outputs', 'actual', self._test_name)
+
+  @property
+  def output_dir_expected(self):
+    assert self._testdata_dir, 'self._testdata_dir must be set'
+    return os.path.join(
+        self._testdata_dir, 'outputs', 'expected', self._test_name)
+
   def shortDescription(self):
     """Tell unittest framework to not print docstrings for test cases."""
     return None
 
   def create_empty_dir(self, path):
     """Creates an empty directory at path and returns path.
 
     Args:
       path: path on local disk
     """
-    shutil.rmtree(path=path, ignore_errors=True)
+    # Delete the old one, if any.
+    if os.path.isdir(path):
+      shutil.rmtree(path=path, ignore_errors=True)
+    elif os.path.lexists(path):
+      os.remove(path)
+
+    # Create the new one.
     try:
       os.makedirs(path)
     except OSError as exc:
+      # Guard against race condition (somebody else is creating the same dir)
       if exc.errno != errno.EEXIST:
         raise
     return path
 
-  def run_command(self, args):
-    """Runs a program from the command line and returns stdout.
 
-    Args:
-      args: Command line to run, as a list of string parameters. args[0] is the
-            binary to run.
+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.
 
-    Returns:
-      stdout from the program, as a single string.
+  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
 
-    Raises:
-      Exception: the program exited with a nonzero return code.
-    """
-    return find_run_binary.run_command(args)
-
-  def find_path_to_program(self, program):
-    """Returns path to an existing program binary.
-
-    Args:
-      program: Basename of the program to find (e.g., 'render_pictures').
-
-    Returns:
-      Absolute path to the program binary, as a string.
-
-    Raises:
-      Exception: unable to find the program binary.
-    """
-    return find_run_binary.find_path_to_program(program)
+  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(test_case_class):
   """Run the unit tests within the given class.
 
   Raises an Exception if any of those tests fail (in case we are running in the
   context of run_all.py, which depends on that Exception to signal failures).
-
-  TODO(epoger): Make all of our unit tests use the Python unittest framework,
-  so we can leverage its ability to run *all* the tests and report failures at
-  the end.
   """
   suite = unittest.TestLoader().loadTestsFromTestCase(test_case_class)
   results = unittest.TextTestRunner(verbosity=2).run(suite)
   if not results.wasSuccessful():
     raise Exception('failed unittest %s' % test_case_class)