diff -r a2d01ed713cb Lib/test/test_filecmp.py
--- a/Lib/test/test_filecmp.py	Sun Aug 03 15:27:18 2014 -0400
+++ b/Lib/test/test_filecmp.py	Sun Aug 03 16:17:39 2014 -0700
@@ -12,19 +12,41 @@
         self.name = support.TESTFN
         self.name_same = support.TESTFN + '-same'
         self.name_diff = support.TESTFN + '-diff'
+        self.name_same_diffsig = support.TESTFN + '-same-diffsig'
+        self.name_diff_samesig = support.TESTFN + '-diff-samesig'
         data = 'Contents of file go here.\n'
-        for name in [self.name, self.name_same, self.name_diff]:
+        for name in [self.name, self.name_same, self.name_diff,
+                     self.name_same_diffsig]:
             with open(name, 'w') as output:
                 output.write(data)
 
         with open(self.name_diff, 'a+') as output:
             output.write('An extra line.\n')
+
+        with open(self.name_diff_samesig, 'w') as output:
+            output.write(data.upper())
+
+        st = os.stat(self.name)
+        atime = st.st_atime
+        mtime = st.st_mtime
+        mtime_diff = mtime - 24*60*60 # yesterday
+
+        # these files are given the same atime and mtime as self.name
+        os.utime(self.name_same, (atime, mtime))
+        os.utime(self.name_diff_samesig, (atime, mtime))
+        
+        # these files get a different mtime
+        os.utime(self.name_diff, (atime, mtime_diff))
+        os.utime(self.name_same_diffsig, (atime, mtime_diff))
+        
         self.dir = tempfile.gettempdir()
 
     def tearDown(self):
         os.unlink(self.name)
         os.unlink(self.name_same)
         os.unlink(self.name_diff)
+        os.unlink(self.name_same_diffsig)
+        os.unlink(self.name_diff_samesig)
 
     def test_matching(self):
         self.assertTrue(filecmp.cmp(self.name, self.name_same),
@@ -49,6 +71,22 @@
         self.assertTrue(len(filecmp._cache) == 0,
                         "Cache not cleared after calling clear_cache")
 
+    def test_shallow_false_negative(self):
+        self.assertFalse(filecmp.cmp(self.name, self.name_same_diffsig),
+                         "Shallow comparison not done by file signature")
+
+    def test_shallow_false_positive(self):
+        self.assertTrue(filecmp.cmp(self.name, self.name_diff_samesig),
+                        "Shallow comparison not done by file signature")
+
+    def test_deep_comparisons(self):
+        self.assertTrue(filecmp.cmp(self.name, self.name_same_diffsig,
+                                    shallow=False),
+                        "Deep comparison not done by file contents")
+        self.assertFalse(filecmp.cmp(self.name, self.name_diff_samesig,
+                                     shallow=False),
+                         "Deep comparison not done by file contents")
+
 class DirCompareTestCase(unittest.TestCase):
     def setUp(self):
         tmpdir = tempfile.gettempdir()
@@ -62,15 +100,17 @@
 
         self.caseinsensitive = os.path.normcase('A') == os.path.normcase('a')
         data = 'Contents of file go here.\n'
-        for dir in (self.dir, self.dir_same, self.dir_diff, self.dir_ignored):
+        shutil.rmtree(self.dir, True)
+        os.mkdir(self.dir)
+        with open(os.path.join(self.dir, "file"), 'w') as output:
+            output.write(data)
+            
+        for dir in (self.dir_same, self.dir_diff, self.dir_ignored):
             shutil.rmtree(dir, True)
-            os.mkdir(dir)
+            shutil.copytree(self.dir, dir)
             if self.caseinsensitive and dir is self.dir_same:
-                fn = 'FiLe'     # Verify case-insensitive comparison
-            else:
-                fn = 'file'
-            with open(os.path.join(dir, fn), 'w') as output:
-                output.write(data)
+                os.rename(os.path.join(dir, "file"),
+                          os.path.join(dir, "FiLe"))
 
         with open(os.path.join(self.dir_diff, 'file2'), 'w') as output:
             output.write('An extra file.\n')
diff -r a2d01ed713cb Lib/test/test_keyword.py
--- a/Lib/test/test_keyword.py	Sun Aug 03 15:27:18 2014 -0400
+++ b/Lib/test/test_keyword.py	Sun Aug 03 16:17:39 2014 -0700
@@ -59,10 +59,12 @@
     def test_real_grammar_and_keyword_file(self):
         self._copy_file_without_generated_keywords(KEYWORD_FILE, TEST_PY_FILE)
         self.addCleanup(support.unlink, TEST_PY_FILE)
-        self.assertFalse(filecmp.cmp(KEYWORD_FILE, TEST_PY_FILE))
+        self.assertFalse(filecmp.cmp(KEYWORD_FILE, TEST_PY_FILE,
+                                     shallow=False))
         self.assertEqual((0, b''), self._generate_keywords(GRAMMAR_FILE,
                                                            TEST_PY_FILE))
-        self.assertTrue(filecmp.cmp(KEYWORD_FILE, TEST_PY_FILE))
+        self.assertTrue(filecmp.cmp(KEYWORD_FILE, TEST_PY_FILE,
+                                    shallow=False))
 
     def test_grammar(self):
         self._copy_file_without_generated_keywords(KEYWORD_FILE, TEST_PY_FILE)
@@ -116,7 +118,8 @@
         self.addCleanup(support.unlink, TEST_PY_FILE)
         self.assertEqual((0, b''), self._generate_keywords(os.devnull,
                                                            TEST_PY_FILE))
-        self.assertTrue(filecmp.cmp(TEST_PY_FILE, PY_FILE_WITHOUT_KEYWORDS))
+        self.assertTrue(filecmp.cmp(TEST_PY_FILE, PY_FILE_WITHOUT_KEYWORDS,
+                                    shallow=False))
 
     def test_keywords_py_without_markers_produces_error(self):
         rc, stderr = self._generate_keywords(os.devnull, os.devnull)