Raise exception for OK service checks with messages (#9958)

* Add exception for good service check messages

* Fix import

datadog_checks_base/datadog_checks/base/stubs/aggregator.py

@@ -10,6 +10,7 @@
 
 from six import iteritems
 
+from ..constants import ServiceCheck
 from ..utils.common import ensure_unicode, to_native_string
 from .common import HistogramBucketStub, MetricStub, ServiceCheckStub
 from .similar import build_similar_elements_msg
@@ -123,6 +124,9 @@ def submit_metric_e2e(
             self._metrics[name].append(MetricStub(name, mtype, value, tags, hostname, device))
 
     def submit_service_check(self, check, check_id, name, status, tags, hostname, message):
+        if status == ServiceCheck.OK and message:
+            raise Exception("Expected empty message on OK service check")
+
         check_tag_names(name, tags)
         self._service_checks[name].append(ServiceCheckStub(check_id, name, status, tags, hostname, message))