diff -up ./tests/test_mex.py.orig ./tests/test_mex.py

--- ./tests/test_mex.py.orig	2018-10-19 00:29:42.000000000 +0200

+++ ./tests/test_mex.py	2018-11-02 01:34:24.851553069 +0100

@@ -25,6 +25,7 @@

 #

 #------------------------------------------------------------------------------

 import os

+from distutils.version import LooseVersion

 import unittest

 import httpretty

 from tests import util

@@ -52,7 +53,10 @@ class Test_Mex(unittest.TestCase):

             mex.discover()

             self.fail('No exception was thrown caused by failed request')

         except Exception as exp:

-            self.assertEqual(exp.args[0], 'Mex Get request returned http error: 500 and server response: HTTPretty :)')

+            if LooseVersion(httpretty.__version__) >= LooseVersion("0.9.0"):

+                self.assertEqual(exp.args[0], 'Mex Get request returned http error: 500 and server response: {"message": "HTTPretty :)"}')

+            else:

+                self.assertEqual(exp.args[0], 'Mex Get request returned http error: 500 and server response: HTTPretty :)')

     @httpretty.activate

     def _happyPathTest(self, file_name, expectedUrl):