Prepare a test for #1479

conftest.py

@@ -1,6 +1,7 @@
 import tempfile
 import shutil
 import os
+import sys
 from functools import partial
 
 import pytest
@@ -16,6 +17,9 @@ collect_ignore = [
     'build/',
     'test/examples',
 ]
+if sys.version_info < (3, 5):
+    # Python 2 not supported syntax
+    collect_ignore.append('test/test_inference/test_mixed.py')
 
 
 # The following hooks (pytest_configure, pytest_unconfigure) are used