[Python-checkins] python/dist/src/Lib/test test_random.py, 1.12.8.2, 1.12.8.3

[rhettinger at users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Lib/test
In directory sc8-pr-cvs1:/tmp/cvs-serv17515/Lib/test

Modified Files:
      Tag: release23-maint
	test_random.py 
Log Message:
SF bug #812202:  randint is always even

* Extend rangrange() to return meaningful results when the range is
  larger than 2**53.  Only applies to the MersenneTwister.  WichmannHill
  was left alone in the absence of a proof showing how multiple calls
  could be combined to produce long bit streams.

* WichmannHill was missing from __all__.



Index: test_random.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/test/test_random.py,v
retrieving revision 1.12.8.2
retrieving revision 1.12.8.3
diff -C2 -d -r1.12.8.2 -r1.12.8.3
*** test_random.py	5 Sep 2003 21:40:30 -0000	1.12.8.2
--- test_random.py	5 Oct 2003 23:35:38 -0000	1.12.8.3
***************
*** 221,224 ****
--- 221,256 ----
          self.gen.seed(seed)
  
+     def test_53_bits_per_float(self):
+         # This should pass whenever a C double has 53 bit precision.
+         span = 2 ** 53
+         cum = 0
+         for i in xrange(100):
+             cum |= int(self.gen.random() * span)
+         self.assertEqual(cum, span-1)
+ 
+     def test_bigrand(self):
+         # The randrange routine should build-up the required number of bits
+         # in stages so that all bit positions are active.
+         span = 2 ** 500
+         cum = 0
+         for i in xrange(100):
+             r = self.gen.randrange(span)
+             self.assert_(0 <= r < span)
+             cum |= r
+         self.assertEqual(cum, span-1)
+ 
+     def test_bigrand_ranges(self):
+         for i in [40,80, 160, 200, 211, 250, 375, 512, 550]:
+             start = self.gen.randrange(2 ** i)
+             stop = self.gen.randrange(2 ** (i-2))
+             if stop <= start:
+                 return
+             self.assert_(start <= self.gen.randrange(start, stop) < stop)
+ 
+     def test_rangelimits(self):
+         for start, stop in [(-2,0), (-(2**60)-2,-(2**60)), (2**60,2**60+2)]:
+             self.assertEqual(Set(range(start,stop)),
+                 Set([self.gen.randrange(start,stop) for i in xrange(100)]))
+ 
  _gammacoeff = (0.9999999999995183, 676.5203681218835, -1259.139216722289,
                771.3234287757674,  -176.6150291498386, 12.50734324009056,