my idea is to have here something like:
```python

def setUp(self):
    # more code here
    self.called1 = self.called2 = 0

def cb1(self, *args):  # same idea for cb2
    if tuple(self.args1) == args:
        self.called1 += 1
    else:
        raise ValueError('Invalid arguments for callback')

def check(*args):
    self.assertEquals(self.called1, 1)
    self.assertEquals(self.called2, 1)
```
This ensures us that the callback was reached exactly once, so we can remove the asserts in the callbacks.
It is desirable that the errors are easily found and follow a callback adds a bit of complexity.