def test_permutations_versus_reference_implementation(two_ints):
num = two_ints[0]
choose = two_ints[1]
result = stats.permutations(num, choose=choose)
reference = stats._permutations_reference(num, choose=choose)
assert result == reference
def test_permutations_there_and_back(two_ints):
num = two_ints[0]
choose = two_ints[1]
result = stats.permutations(num, choose=choose)
top_to_bottom = [result]
top_to_bottom.extend(range(num, num - choose, -1))
and_back = reduce(operator.truediv, top_to_bottom)
assert round(and_back) == 1
def test_permutations_factorial(integer):
result = stats.permutations(integer)
assert result == factorial(integer)
def test_permutations_slow_number_equal_choose(integer):
result = stats.permutations(integer)
result_choose = stats.permutations(integer, choose=integer)
assert result == result_choose