Add some tests for check_dummies (#19146)

utils/check_dummies.py

@@ -105,9 +105,10 @@ def create_dummy_object(name, backend_name):
         return DUMMY_CLASS.format(name, backend_name)
 
 
-def create_dummy_files():
+def create_dummy_files(backend_specific_objects=None):
     """Create the content of the dummy files."""
-    backend_specific_objects = read_init()
+    if backend_specific_objects is None:
+        backend_specific_objects = read_init()
     # For special correspondence backend to module name as used in the function requires_modulename
     dummy_files = {}