Issue #13355: Raise ValueError on random.triangular call with invalid params.
Initial patch by Yuriy Senko.
diff --git a/Lib/random.py b/Lib/random.py
index af04ab2..8560fb9 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -367,6 +367,16 @@
http://en.wikipedia.org/wiki/Triangular_distribution
"""
+ # Sanity check. According to the doc low must be less or equal to
+ # high. And mode should be somewhere between these bounds.
+ if low > high:
+ raise ValueError('high cannot be less then low.')
+ if mode is not None and (mode < low or mode > high):
+ raise ValueError('mode must be between low and high.')
+
+ if high == low:
+ return low
+
u = self.random()
c = 0.5 if mode is None else (mode - low) / (high - low)
if u > c:
diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
index 3316415..75e1afc 100644
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -43,6 +43,33 @@
self.assertRaises(TypeError, self.gen.seed, 1, 2)
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)
+
def test_jumpahead(self):
self.gen.seed()
state1 = self.gen.getstate()
@@ -543,7 +570,7 @@
for variate, args, expected in [
(g.uniform, (10.0, 10.0), 10.0),
(g.triangular, (10.0, 10.0), 10.0),
- #(g.triangular, (10.0, 10.0, 10.0), 10.0),
+ (g.triangular, (10.0, 10.0, 10.0), 10.0),
(g.expovariate, (float('inf'),), 0.0),
(g.vonmisesvariate, (3.0, float('inf')), 3.0),
(g.gauss, (10.0, 0.0), 10.0),
diff --git a/Misc/ACKS b/Misc/ACKS
index 4de44cc..9480f2d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -907,6 +907,7 @@
Žiga Seilnach
Yury Selivanov
Fred Sells
+Yuriy Senko
Jiwon Seo
Joakim Sernbrant
Roger Serwy
diff --git a/Misc/NEWS b/Misc/NEWS
index 62e809a..c4d9635 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -22,6 +22,9 @@
Library
-------
+- Issue #13355: Raise ValueError on random.triangular call with invalid params.
+ Initial patch by Yuriy Senko.
+
- Issue #17666: Fix reading gzip files with an extra field.
- Issue #13150, #17512: sysconfig no longer parses the Makefile and config.h