Assert that a PropertyMock was called on a specific instance

I have successfully mocked a property with PropertyMock, but I can't figure out how to check which instance of the class has had that property called. How can I assert that the property was called on one object, but not on another?

Here's an example where I want to assert that foo1.is_big was called, and foo2.is_big was not:

from mock import PropertyMock, patch


class Foo(object):
    def __init__(self, size):
        self.size = size

    @property
    def is_big(self):
        return self.size > 5

f = Foo(3)
g = Foo(10)
assert not f.is_big
assert g.is_big

with patch('__main__.Foo.is_big', new_callable=PropertyMock) as mock_is_big:
    mock_is_big.return_value = True
    foo1 = Foo(4)
    foo2 = Foo(9)

    should_pass = False
    if should_pass:
        is_big = foo1.is_big
    else:
        is_big = foo2.is_big
    assert is_big
    # How can I make this pass when should_pass is True, and fail otherwise?
    mock_is_big.assert_called_once_with()

print('Done.')

The current code will pass when either one of them is called.