fix!: add workaround for invalid Content-Type in response objects

tdd/__init__.py

@@ -66,6 +66,36 @@
 
 TD_TRANSFORMERS = []
 
+def apply_response_content_type_fix(thing_description):
+    """
+        This function applies the workaround described in WoT Discovery issue
+        https://github.com/w3c/wot-discovery/issues/465 to let the TD exposed
+        by the TDD pass JSON Schema validation.
+
+        The workaround is needed since the contentType field in the TD
+        specification the "response" objects has been defined as mandatory
+        without providing a default, making the TD for TDDs included in the
+        Discovery Recommendation invalid (also see
+        https://github.com/w3c/wot-thing-description/issues/1780).
+        This issue should probably be fixed in the 2.0 version of the TD
+        specification, which render this workaround obsolete.
+    """
+    actionsToFix = ['createThing', 'updateThing', 'deleteThing']
+
+    print(thing_description["actions"].keys())
+    for key in actionsToFix:
+
+      forms = thing_description["actions"].get(key, {}).get("forms", [])
+
+      for form in forms:
+          response = form.get("response")
+
+          if response is None:
+            continue
+
+          if response.get("contentType") is None:
+            response["contentType"] = "application/x-empty"
+
 
 def wait_for_sparqlendpoint():
     test_num = 0
@@ -174,6 +204,7 @@ def directory_description():
         with files(__package__).joinpath("data/tdd-description.json").open() as strm:
             tdd_description = json.load(strm)
             tdd_description["base"] = CONFIG["TD_REPO_URL"]
+            apply_response_content_type_fix(tdd_description)
             return Response(
                 json.dumps(tdd_description), content_type="application/td+json"
             )