[Python] python unittest How to patch a function with an injected argument and modify it

Try to unittest the function to test which used a function with an injected Element I know how to patch the return value of function_to_patch but how to alter the injected element ?

@dataclass
class Element:
type: str
name:str
tags: List[str]
nb_elt:int


def function_to_patch(injected_arg:Element )-> Tuple[List[str], int]:
do_something()

injected_arg.tags=["tag1","tag3"]
return (["somedata"], 0)


def function_to_test()-> str:
injected_arg= Element()
do_something...
mylist, myval = function_to_patch(injected_arg)
....
return Element.tags[1]




With this approach the result is not correct The result does not contain the expected "tag3" as I have no idea on how to alter the injected_arg

@mock.patch("function_to_patch")
def TestsFunctionToTest(self, patch_of_function_to_patch):

patch_of_function_to_patch.return_value=("my return",3)

result = function_to_test()
assertEqual(result, "tag3")

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