Refactor: separate models.Device method for device JSON obj

models.py

@@ -93,13 +93,23 @@ class Device:
         '''Generate a JSON format request body'''
 
         obj = {
-            'devices': [{
-                'mac': self.mac,
-                'sensors': [],
-            }]
+            'devices': [
+                self._json_device_obj(),
+            ]
+        }
+
+        return json.dumps(obj)
+
+    def _json_device_obj(self) -> dict[str, Any]:
+        '''Create a device JSON object for json_req_data().
+        Moved to a separate function to allow performing tests
+        with multiple devices in a request at once.'''
+
+        dev = {
+            'mac': self.mac,
+            'sensors': [],
         }
 
-        dev = obj['devices'][0]
         if self.name is not None:
             dev['name'] = self.name
         if self.owner is not None:
@@ -121,4 +131,4 @@ class Device:
                 sobj['name'] = s.name
             sl.append(sobj)
 
-        return json.dumps(obj)
+        return dev