diff --git a/flake8/tests/test_engine.py b/flake8/tests/test_engine.py
index 6859ff0..ba04bce 100644
--- a/flake8/tests/test_engine.py
+++ b/flake8/tests/test_engine.py
@@ -1,8 +1,21 @@
 from flake8 import engine
 import unittest
+import mock
 
 
 class TestEngine(unittest.TestCase):
     def test_get_style_guide(self):
-        g = engine.get_style_guide()
-        self.assertTrue(isinstance(g, engine.StyleGuide))
+        with mock.patch('flake8.engine._register_extensions') as reg_ext:
+            reg_ext.return_value = ([], [], [])
+            g = engine.get_style_guide()
+            self.assertTrue(isinstance(g, engine.StyleGuide))
+            reg_ext.assert_called_once_with()
+
+    def test_get_style_guide_kwargs(self):
+        m = mock.Mock()
+        with mock.patch('flake8.engine.StyleGuide') as StyleGuide:
+            with mock.patch('flake8.engine.get_parser') as get_parser:
+                get_parser.return_value = (m, [])
+                engine.get_style_guide(foo='bar')
+                get_parser.assert_called_once_with()
+            StyleGuide.assert_called_once_with(**{'parser': m, 'foo': 'bar'})