--- a/pymysql/tests/test_connection.py
+++ b/pymysql/tests/test_connection.py
@@ -70,6 +70,9 @@ class TestAuthentication(base.PyMySQLTestCase):
     for r in cur:
         if (r[1], r[2]) !=  (u'ACTIVE', u'AUTHENTICATION'):
             continue
+        if r[0] == u'unix_socket':
+            socket_plugin_name = r[0]
+            socket_found = True
         if r[3] ==  u'auth_socket.so':
             socket_plugin_name = r[0]
             socket_found = True
@@ -188,7 +191,7 @@ class TestAuthentication(base.PyMySQLTestCase):
             cur.execute("install plugin two_questions soname 'dialog_examples.so'")
             TestAuthentication.two_questions_found = True
             self.realTestDialogAuthTwoQuestions()
-        except pymysql.err.InternalError:
+        except pymysql.err.OperationalError:
             pytest.skip('we couldn\'t install the two_questions plugin')
         finally:
             if TestAuthentication.two_questions_found:
@@ -218,7 +221,7 @@ class TestAuthentication(base.PyMySQLTestCase):
             cur.execute("install plugin three_attempts soname 'dialog_examples.so'")
             TestAuthentication.three_attempts_found = True
             self.realTestDialogAuthThreeAttempts()
-        except pymysql.err.InternalError:
+        except pymysql.err.OperationalError:
             pytest.skip('we couldn\'t install the three_attempts plugin')
         finally:
             if TestAuthentication.three_attempts_found: