[qa] add assert_raises_message to check specific error message

Github-Pull: #9168
Rebased-From: 307acdd3df03082295ac0f7fe9eba7dd35973bc4

qa/rpc-tests/test_framework/util.py

@@ -508,10 +508,14 @@ def assert_greater_than(thing1, thing2):
         raise AssertionError("%s <= %s"%(str(thing1),str(thing2)))
 
 def assert_raises(exc, fun, *args, **kwds):
+    assert_raises_message(exc, None, fun, *args, **kwds)
+
+def assert_raises_message(exc, message, fun, *args, **kwds):
     try:
         fun(*args, **kwds)
-    except exc:
-        pass
+    except exc as e:
+        if message is not None and message not in e.error['message']:
+            raise AssertionError("Expected substring not found:"+e.error['message'])
     except Exception as e:
         raise AssertionError("Unexpected exception raised: "+type(e).__name__)
     else: