Add a test for operation name collisions and fix the one additional collision found

endpoints/api/discovery.py

@@ -65,6 +65,7 @@ def swagger_route_data(include_internal=False, compact=False):
   models = {}
   tags = []
   tags_added = set()
+  operationIds = set()
 
   for rule in app.url_map.iter_rules():
     endpoint_method = app.view_functions[rule.endpoint]
@@ -125,13 +126,20 @@ def swagger_route_data(include_internal=False, compact=False):
         logger.debug('Unable to find method for %s in class %s', method_name, view_class)
         continue
 
+      operationId = method_metadata(method, 'nickname')
       operation_swagger = {
-        'operationId': method_metadata(method, 'nickname'),
+        'operationId': operationId,
         'parameters': [],
       }
-      if operation_swagger['operationId'] is None:
+
+      if operationId is None:
         continue
 
+      if operationId in operationIds:
+        raise Exception('Duplicate operation Id: %s' % operationId)
+
+      operationIds.add(operationId)
+
       if not compact:
         operation_swagger.update({
           'description': method.__doc__.strip() if method.__doc__ else '',