def test_Trackers_flat_property():
tiers = utils.Trackers((['http://foo:123'], ['http://bar:456']))
assert tiers.flat == ('http://foo:123', 'http://bar:456')
def test_Trackers_removes_empty_tier_automatically():
tiers = utils.Trackers(('http://foo:123', 'http://bar:456'))
assert tiers == [['http://foo:123'], ['http://bar:456']]
tiers[0].remove('http://foo:123')
assert tiers == [['http://bar:456']]