added conftest.py

wafo/spectrum/test/conftest.py

@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""
+    Dummy conftest.py for wafo.
+
+    If you don't know what this is for, just leave it empty.
+    Read more about conftest.py under:
+    https://pytest.org/latest/plugins.html
+"""
+from __future__ import print_function, absolute_import, division
+
+import pytest