Add Context Manager Interface to Connection. (#413)

Fixes #400.

MySQLdb/connections.py

@@ -207,6 +207,12 @@ class Connection(_mysql.connection):
                 self.autocommit(autocommit)
         self.messages = []
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
     def autocommit(self, on):
         on = bool(on)
         if self.get_autocommit() != on:

tests/test_MySQLdb_nonstandard.py

@@ -99,3 +99,8 @@ class CoreAPI(unittest.TestCase):
 
     def test_fileno(self):
         self.assertGreaterEqual(self.conn.fileno(), 0)
+
+    def test_context_manager(self):
+        with connection_factory() as conn:
+            self.assertFalse(conn.closed)
+        self.assertTrue(conn.closed)