python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/unittest/test/testmock/testsentinel.py

@@ -0,0 +1,28 @@
+import unittest
+from unittest.mock import sentinel, DEFAULT
+
+
+class SentinelTest(unittest.TestCase):
+
+    def testSentinels(self):
+        self.assertEqual(sentinel.whatever, sentinel.whatever,
+                         'sentinel not stored')
+        self.assertNotEqual(sentinel.whatever, sentinel.whateverelse,
+                            'sentinel should be unique')
+
+
+    def testSentinelName(self):
+        self.assertEqual(str(sentinel.whatever), 'sentinel.whatever',
+                         'sentinel name incorrect')
+
+
+    def testDEFAULT(self):
+        self.assertIs(DEFAULT, sentinel.DEFAULT)
+
+    def testBases(self):
+        # If this doesn't raise an AttributeError then help(mock) is broken
+        self.assertRaises(AttributeError, lambda: sentinel.__bases__)
+
+
+if __name__ == '__main__':
+    unittest.main()