fix: change the default value of ruleset_stats of activation to empty string (#1116)

Author: hsong-rh

src/aap_eda/api/serializers/activation.py

@@ -516,6 +516,7 @@ class ActivationReadSerializer(serializers.ModelSerializer):
     rules_count = serializers.IntegerField()
     rules_fired_count = serializers.IntegerField()
     ruleset_stats = YAMLSerializerField(
+        required=True,
         sort_keys=False,
         help_text="The stat information about the activation",
     )
@@ -629,7 +630,7 @@ def to_representation(self, activation):
                 activation.ruleset_stats
             )
             if activation.ruleset_stats
-            else None
+            else ""
         )
 
         return {

tests/integration/api/test_activation.py

@@ -413,7 +413,7 @@ def test_retrieve_activation(
     assert response.status_code == status.HTTP_200_OK
     data = response.data
     assert_activation_base_data(data, default_activation)
-    assert data["ruleset_stats"] is None
+    assert data["ruleset_stats"] == ""
     if default_activation.project:
         assert data["project"]["id"] == default_activation.project.id
     else: