test(ab): allow dimensions to be split into multiple lists

When using metrics.put_dimensions from python code, then the resulting
EMF messages will have a list of lists in their "Dimensions" key.
Currently, ab_test.py assumes that this list of lists always has length
one, meaning it ignores additional dimensions added via put_dimensions.
Have it instead flatten the list of lists so that it always considers
all dimensions.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tools/ab_test.py

@@ -64,7 +64,11 @@ def extract_dimensions(emf):
         # Skipped tests emit a duration metric, but have no dimensions set
         return {}
 
-    dimension_list = emf["_aws"]["CloudWatchMetrics"][0]["Dimensions"][0]
+    dimension_list = [
+        dim
+        for dimensions in emf["_aws"]["CloudWatchMetrics"][0]["Dimensions"]
+        for dim in dimensions
+    ]
     return {key: emf[key] for key in emf if key in dimension_list}