gistfile1.py

def test_it_location_is_not_dir():
    from somewhere import Config
    c = Config()
    c.os = DummyOS(False)
    assertRaises(SomeException, setattr, c, settings_location, '/whatever')

def test_it_location_is_dir():
    from somewhere import Config
    c = Config()
    c.os = DummyOS(True)
    c.settings_location = 'foo'
    assert c.settings_location == 'foo'
    
    
class DummyOS(object):
    def __init__(self, result):
        self.result = result
    @property
    def path(self):
        return self
    def isdir(self, location):
        return self.result