Filter out expected warnings

Author: Ognyan Moore

pytest.ini

@@ -12,4 +12,8 @@ filterwarnings =
     ignore:numpy.ufunc size changed, may indicate binary incompatibility.*:RuntimeWarning
     # Warnings generated from PyQt5.9
     ignore:This method will be removed in future versions.  Use 'tree.iter\(\)' or 'list\(tree.iter\(\)\)' instead.:PendingDeprecationWarning
-    ignore:'U' mode is deprecated\nplugin = open\(filename, 'rU'\):DeprecationWarning
+    ignore:.*'U' mode is deprecated.*:DeprecationWarning
+    # py36/pyside2_512 specific issue
+    ignore:split\(\) requires a non-empty pattern match\.:FutureWarning
+    # pyqtgraph specific warning we want to ignore during testing
+    ignore:Visible window deleted. To prevent this, store a reference to the window object.