fix test suite (pytest changes in ExceptionInfo class)
diff --git a/tests/test_smart_ptr.py b/tests/test_smart_ptr.py
index 0a3bb58..c662704 100644
--- a/tests/test_smart_ptr.py
+++ b/tests/test_smart_ptr.py
@@ -272,7 +272,8 @@
     instance = m.HeldByDefaultHolder()
     with pytest.raises(RuntimeError) as excinfo:
         m.HeldByDefaultHolder.load_shared_ptr(instance)
-    assert "Unable to load a custom holder type from a default-holder instance" in str(excinfo)
+    assert "Unable to load a custom holder type from a " \
+           "default-holder instance" in str(excinfo.value)
 
 
 def test_shared_ptr_gc():