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bpo-40282: Allow random.getrandbits(0) (GH-19539)

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Antoine Pitrou 2020-04-17 19:32:14 +02:00 • committed by GitHub
parent d7c657d4b1
commit 75a3378810
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5 changed files with 42 additions and 44 deletions
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69
Lib/test/test_random.py
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@ -263,6 +263,31 @@ class TestBasicOps:
self.assertEqual(x1, x2)
self.assertEqual(y1, y2)
def test_getrandbits(self):
# Verify ranges
for k in range(1, 1000):
self.assertTrue(0 <= self.gen.getrandbits(k) < 2**k)
self.assertEqual(self.gen.getrandbits(0), 0)
# Verify all bits active
getbits = self.gen.getrandbits
for span in [1, 2, 3, 4, 31, 32, 32, 52, 53, 54, 119, 127, 128, 129]:
all_bits = 2**span-1
cum = 0
cpl_cum = 0
for i in range(100):
v = getbits(span)
cum |= v
cpl_cum |= all_bits ^ v
self.assertEqual(cum, all_bits)
self.assertEqual(cpl_cum, all_bits)
# Verify argument checking
self.assertRaises(TypeError, self.gen.getrandbits)
self.assertRaises(TypeError, self.gen.getrandbits, 1, 2)
self.assertRaises(ValueError, self.gen.getrandbits, -1)
self.assertRaises(TypeError, self.gen.getrandbits, 10.1)
def test_pickling(self):
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
state = pickle.dumps(self.gen, proto)
@ -390,26 +415,6 @@ class SystemRandom_TestBasicOps(TestBasicOps, unittest.TestCase):
raises(0, 42, 0)
raises(0, 42, 3.14159)
def test_genrandbits(self):
# Verify ranges
for k in range(1, 1000):
self.assertTrue(0 <= self.gen.getrandbits(k) < 2**k)
# Verify all bits active
getbits = self.gen.getrandbits
for span in [1, 2, 3, 4, 31, 32, 32, 52, 53, 54, 119, 127, 128, 129]:
cum = 0
for i in range(100):
cum |= getbits(span)
self.assertEqual(cum, 2**span-1)
# Verify argument checking
self.assertRaises(TypeError, self.gen.getrandbits)
self.assertRaises(TypeError, self.gen.getrandbits, 1, 2)
self.assertRaises(ValueError, self.gen.getrandbits, 0)
self.assertRaises(ValueError, self.gen.getrandbits, -1)
self.assertRaises(TypeError, self.gen.getrandbits, 10.1)
def test_randbelow_logic(self, _log=log, int=int):
# check bitcount transition points: 2**i and 2**(i+1)-1
# show that: k = int(1.001 + _log(n, 2))
@ -629,34 +634,18 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase):
self.assertEqual(set(range(start,stop)),
set([self.gen.randrange(start,stop) for i in range(100)]))
def test_genrandbits(self):
def test_getrandbits(self):
super().test_getrandbits()
# Verify cross-platform repeatability
self.gen.seed(1234567)
self.assertEqual(self.gen.getrandbits(100),
97904845777343510404718956115)
# Verify ranges
for k in range(1, 1000):
self.assertTrue(0 <= self.gen.getrandbits(k) < 2**k)
# Verify all bits active
getbits = self.gen.getrandbits
for span in [1, 2, 3, 4, 31, 32, 32, 52, 53, 54, 119, 127, 128, 129]:
cum = 0
for i in range(100):
cum |= getbits(span)
self.assertEqual(cum, 2**span-1)
# Verify argument checking
self.assertRaises(TypeError, self.gen.getrandbits)
self.assertRaises(TypeError, self.gen.getrandbits, 'a')
self.assertRaises(TypeError, self.gen.getrandbits, 1, 2)
self.assertRaises(ValueError, self.gen.getrandbits, 0)
self.assertRaises(ValueError, self.gen.getrandbits, -1)
def test_randrange_uses_getrandbits(self):
# Verify use of getrandbits by randrange
# Use same seed as in the cross-platform repeatability test
# in test_genrandbits above.
# in test_getrandbits above.
self.gen.seed(1234567)
# If randrange uses getrandbits, it should pick getrandbits(100)
# when called with a 100-bits stop argument.