def test_happy_days(self):
'''Test various regular inputs'''
assert list(flatten([[2, 3], 1, [5, [7, 8]]])) == [2, 3, 1, 5, [7, 8]]
assert list(flatten([[2, 3], 1, [5, [7, 8]]], times=2)) == [2, 3, 1, 5, 7, 8]
assert list(flatten([[2, 3], 1, [5, [7, 8]]], times=3)) == [2, 3, 1, 5, 7, 8]
assert list(flatten([[2, 3], 1, [5, [7, 8]]], times=0)) == [[2, 3], 1, [5, [7, 8]]]
# Deep things are left alone (not iterators turned into lists or lists turned into sets or ...
iterator = iter([7, 8])
assert list(flatten([iter([2, 3]), 1, [{1,2}, iterator]])) == [2, 3, 1, {1,2}, iterator]
def test_empty(self, times):
'''When flatten empty, return iter(empty)'''
assert list(flatten([], times=times)) == []
def test_invalid_times(self):
with pytest.raises(ValueError):
'''When times < 0, ValueError'''
list(flatten([1], times=-1))
