Issue #13355: Raise ValueError on random.triangular call with invalid params.

Initial patch by Yuriy Senko.

diff --cc Lib/random.py
Simple merge

diff --cc Lib/test/test_random.py
index ed5a48a4bf99c4281b04272a3093907359c81261,7b4b11026be3da8875c66ffbdf1ff205ce38be58..84f81ee114a0745809962e54846515186c02bf14
--- 1/Lib/test/test_random.py
--- 2/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@@ -48,49 -46,36 +48,75 @@@ class TestBasicOps(unittest.TestCase)
          self.assertRaises(TypeError, self.gen.seed, 1, 2, 3, 4)
          self.assertRaises(TypeError, type(self.gen), [])
  
 -
+     def test_triangular(self):
+         # Check that triangular() correctly handles bad input. See issue 13355.
 -
+         # mode > high.
+         with self.assertRaises(ValueError):
+             random.triangular(mode=2)
+         with self.assertRaises(ValueError):
+             random.triangular(low=1, high=10, mode=11)
+         with self.assertRaises(ValueError):
+             random.triangular(low=1, high=1, mode=11)
 -
+         # mode < low.
+         with self.assertRaises(ValueError):
+             random.triangular(mode=-1)
+         with self.assertRaises(ValueError):
+             random.triangular(low=1, high=10, mode=0)
+         with self.assertRaises(ValueError):
+             random.triangular(low=1, high=1, mode=0)
- 
+         # low > high
+         with self.assertRaises(ValueError):
+             random.triangular(low=5, high=2)
+         with self.assertRaises(ValueError):
+             random.triangular(low=5, high=2, mode=1)
+         with self.assertRaises(ValueError):
+            random.triangular(low=-2, high=-5)
+ 
+         self.assertEqual(random.triangular(low=10, high=10), 10)
+         self.assertEqual(random.triangular(low=10, high=10, mode=10), 10)
+ 
 +    @unittest.mock.patch('random._urandom') # os.urandom
 +    def test_seed_when_randomness_source_not_found(self, urandom_mock):
 +        # Random.seed() uses time.time() when an operating system specific
 +        # randomness source is not found. To test this on machines were it
 +        # exists, run the above test, test_seedargs(), again after mocking
 +        # os.urandom() so that it raises the exception expected when the
 +        # randomness source is not available.
 +        urandom_mock.side_effect = NotImplementedError
 +        self.test_seedargs()
 +
 +    def test_shuffle(self):
 +        shuffle = self.gen.shuffle
 +        lst = []
 +        shuffle(lst)
 +        self.assertEqual(lst, [])
 +        lst = [37]
 +        shuffle(lst)
 +        self.assertEqual(lst, [37])
 +        seqs = [list(range(n)) for n in range(10)]
 +        shuffled_seqs = [list(range(n)) for n in range(10)]
 +        for shuffled_seq in shuffled_seqs:
 +            shuffle(shuffled_seq)
 +        for (seq, shuffled_seq) in zip(seqs, shuffled_seqs):
 +            self.assertEqual(len(seq), len(shuffled_seq))
 +            self.assertEqual(set(seq), set(shuffled_seq))
 +        # The above tests all would pass if the shuffle was a
 +        # no-op. The following non-deterministic test covers that.  It
 +        # asserts that the shuffled sequence of 1000 distinct elements
 +        # must be different from the original one. Although there is
 +        # mathematically a non-zero probability that this could
 +        # actually happen in a genuinely random shuffle, it is
 +        # completely negligible, given that the number of possible
 +        # permutations of 1000 objects is 1000! (factorial of 1000),
 +        # which is considerably larger than the number of atoms in the
 +        # universe...
 +        lst = list(range(1000))
 +        shuffled_lst = list(range(1000))
 +        shuffle(shuffled_lst)
 +        self.assertTrue(lst != shuffled_lst)
 +        shuffle(lst)
 +        self.assertTrue(lst != shuffled_lst)
 +
      def test_choice(self):
          choice = self.gen.choice
          with self.assertRaises(IndexError):

diff --cc Misc/ACKS
Simple merge

diff --cc Misc/NEWS
Simple merge