fix: metric dimension in root blob

Author: heitorlessa

python/aws_lambda_powertools/metrics/base.py

@@ -177,6 +177,7 @@ def serialize_metric_set(self, metrics: Dict = None, dimensions: Dict = None) ->
         }
         metrics_timestamp = {"Timestamp": int(datetime.datetime.now().timestamp() * 1000)}
         metric_set["_aws"] = {**metrics_timestamp, **metrics_definition}
+        metric_set.update(**dimensions)
 
         try:
             logger.debug("Validating serialized metrics against CloudWatch EMF schema", metric_set)

python/tests/functional/test_metrics.py

@@ -155,6 +155,8 @@ def lambda_handler(evt, handler):
 
     remove_timestamp(metrics=[output, expected])  # Timestamp will always be different
     assert expected["_aws"] == output["_aws"]
+    for dimension in dimensions:
+        assert dimension['name'] in output
 
 
 def test_namespace_env_var(monkeypatch, capsys, metric, dimension, namespace):