def test_combinations_float(self):
"""combinations should use gamma function when floats as input"""
self.assertFloatEqual(combinations(1.0,1.0), 1)
self.assertFloatEqual(combinations(2.0,1.0), 2)
self.assertFloatEqual(combinations(3.0,1.0), 3)
self.assertFloatEqual(combinations(4.0,1.0), 4)
self.assertFloatEqual(combinations(4.0,2), 6)
self.assertFloatEqual(combinations(4,3.0), 4)
self.assertFloatEqual(combinations(4.0,4.0), 1)
self.assertFloatEqual(combinations(20.0,4.0), 19*17*15)
self.assertFloatEqual(combinations(300,100.0),4.1582514632578812e81)
def test_combinations(self):
"""combinations should return expected results when int as input"""
self.assertEqual(combinations(1,1), 1)
self.assertEqual(combinations(2,1), 2)
self.assertEqual(combinations(3,1), 3)
self.assertEqual(combinations(4,1), 4)
self.assertEqual(combinations(4,2), 6)
self.assertEqual(combinations(4,3), 4)
self.assertEqual(combinations(4,4), 1)
self.assertEqual(combinations(20,4), 19*17*15)
self.assertFloatEqual(combinations(300, 100), 4.1582514632578812e+81)
def test_combinations_range(self):
"""combinations should decrease gradually with increasing k"""
start = 5 #combinations(10,5) = 252
end = 6 #combinations(10,6) = 210
step = 0.1
lower_lim = 210
upper_lim = 252
previous_value = 252.00001
while start <= end:
obs = combinations(10,start)
assert lower_lim <= obs <= upper_lim
assert obs < previous_value
previous_value = obs
start += step
