Try this exec modification

Médéric Ribreux · Médéric RIBREUX · commit cd7047cc7c7f · 2016-05-29T09:00:16.000+02:00
diff --git a/python/plugins/processing/tests/AlgorithmsTestBase.py b/python/plugins/processing/tests/AlgorithmsTestBase.py
@@ -99,7 +99,7 @@ def check_algorithm(self, name, defs):
 
         expectFailure = False
         if 'expectedFailure' in defs:
-            exec(('\n'.join(defs['expectedFailure'][:-1])), globals(), locals())
+            exec('\n'.join(defs['expectedFailure'][:-1]), globals(), locals())
             expectFailure = eval(defs['expectedFailure'][-1])
 
         def doCheck():
