itertools._tee object has no attribute error with 3.15.0

[kasium]

With the newest version (3.15.0) the below code fails with AttributeError: 'itertools._tee' object has no attribute 'start'

foo.py

class Client:
    def start(self):
        pass

class Lock:
    def create_client(self):
        return Client()
    def start(self):
        self._client = self.create_client()
        self._client.start()

test_foo.py

import foo

def test(mocker):
    mocker.patch("foo.Client")
    lock = foo.Lock()
    mocker.spy(lock, "create_client")
    lock.start()

The problem ist, that spy checks if the returned instance is an iterator, but each MagicMock is an iterator which leads to issues.
The logic should exclude any mock object IMO which should solve the issue

[nicoddemus]

Thanks @kasium for the report!

@vokracko could you take a look at this?

[vokracko]

Apologies for the regression, it was introduced by myself in:

• Add spy_return_iter attribute to spy #524

The logic should exclude any mock object IMO which should solve the issue

I don't think this would be good approach. It could lead to unexpected behaviour when somebody would use MagicMock as an Iterator.

Given how niche the spy_return_iter usage is I propose to enable that behavior only when explicitly requested:

- def spy(self, obj: object, name: str) -> MockType:
+ def spy(self, obj: object, name: str, duplicate_iterators: bool = False) -> MockType:

What do you think @nicoddemus?

[nicoddemus]

Given how niche the spy_return_iter usage is I propose to enable that behavior only when explicitly requested:

Sounds good!

Could you work on that @vokracko ?

[vokracko]

Done in #537