it would be nice to have arrange, act, assert format... I think there is a missing new line before ```value = ```

Also, session.expire() is not really part of the test... but rather a cleanup.

you can do something like this:

```

def setUp():
    super()
    self.session = MAKE_SESSION

def tearDown():
   if self.session and self.session.notExpired():
       self.session.expire
   super()

def test_bla():
    request.setHeader(self.session.id)

```
What do you think?