SF patch 658251: Install a C implementation of the Mersenne Twister as the

core generator for random.py.

1 files changed, 201 insertions, 14 deletions

diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
index 5f60f4b..d0a2a15 100644
--- a/Lib/test/test_random.py
+++ b/Lib/test/test_random.py
@@ -1,19 +1,206 @@
-from test import test_support
+#!/usr/bin/env python
+
+import unittest
 import random
+import time
+from test import test_support
+
+class TestBasicOps(unittest.TestCase):
+    # Superclass with tests common to all generators.
+    # Subclasses must arrange for self.gen to retrieve the Random instance
+    # to be tested.
+
+    def randomlist(self, n):
+        """Helper function to make a list of random numbers"""
+        return [self.gen.random() for i in xrange(n)]
+
+    def test_autoseed(self):
+        self.gen.seed()
+        state1 = self.gen.getstate()
+        time.sleep(1)
+        self.gen.seed()      # diffent seeds at different times
+        state2 = self.gen.getstate()
+        self.assertNotEqual(state1, state2)
+
+    def test_saverestore(self):
+        N = 1000
+        self.gen.seed()
+        state = self.gen.getstate()
+        randseq = self.randomlist(N)
+        self.gen.setstate(state)    # should regenerate the same sequence
+        self.assertEqual(randseq, self.randomlist(N))
+
+    def test_seedargs(self):
+        for arg in [None, 0, 0L, 1, 1L, -1, -1L, 10**20, -(10**20),
+                    3.14, 1+2j, 'a', tuple('abc')]:
+            self.gen.seed(arg)
+        for arg in [range(3), dict(one=1)]:
+            self.assertRaises(TypeError, self.gen.seed, arg)
+
+    def test_jumpahead(self):
+        self.gen.seed()
+        state1 = self.gen.getstate()
+        self.gen.jumpahead(100)
+        state2 = self.gen.getstate()    # s/b distinct from state1
+        self.assertNotEqual(state1, state2)
+        self.gen.jumpahead(100)
+        state3 = self.gen.getstate()    # s/b distinct from state2
+        self.assertNotEqual(state2, state3)
+
+        self.assertRaises(TypeError, self.gen.jumpahead)  # needs an arg
+        self.assertRaises(TypeError, self.gen.jumpahead, "ick")  # wrong type
+        self.assertRaises(TypeError, self.gen.jumpahead, 2.3)  # wrong type
+        self.assertRaises(TypeError, self.gen.jumpahead, 2, 3)  # too many
+
+    def test_sample(self):
+        # For the entire allowable range of 0 <= k <= N, validate that
+        # the sample is of the correct length and contains only unique items
+        N = 100
+        population = xrange(N)
+        for k in xrange(N+1):
+            s = self.gen.sample(population, k)
+            self.assertEqual(len(s), k)
+            uniq = dict.fromkeys(s)
+            self.assertEqual(len(uniq), k)
+            self.failIf(None in uniq)
+
+    def test_gauss(self):
+        # Ensure that the seed() method initializes all the hidden state.  In
+        # particular, through 2.2.1 it failed to reset a piece of state used
+        # by (and only by) the .gauss() method.
+
+        for seed in 1, 12, 123, 1234, 12345, 123456, 654321:
+            self.gen.seed(seed)
+            x1 = self.gen.random()
+            y1 = self.gen.gauss(0, 1)
+
+            self.gen.seed(seed)
+            x2 = self.gen.random()
+            y2 = self.gen.gauss(0, 1)
+
+            self.assertEqual(x1, x2)
+            self.assertEqual(y1, y2)
+
+
+class WichmannHill_TestBasicOps(TestBasicOps):
+    gen = random.WichmannHill()
+
+    def test_strong_jumpahead(self):
+        # tests that jumpahead(n) semantics correspond to n calls to random()
+        N = 1000
+        s = self.gen.getstate()
+        self.gen.jumpahead(N)
+        r1 = self.gen.random()
+        # now do it the slow way
+        self.gen.setstate(s)
+        for i in xrange(N):
+            self.gen.random()
+        r2 = self.gen.random()
+        self.assertEqual(r1, r2)
+
+    def test_gauss_with_whseed(self):
+        # Ensure that the seed() method initializes all the hidden state.  In
+        # particular, through 2.2.1 it failed to reset a piece of state used
+        # by (and only by) the .gauss() method.
+
+        for seed in 1, 12, 123, 1234, 12345, 123456, 654321:
+            self.gen.whseed(seed)
+            x1 = self.gen.random()
+            y1 = self.gen.gauss(0, 1)
+
+            self.gen.whseed(seed)
+            x2 = self.gen.random()
+            y2 = self.gen.gauss(0, 1)
+
+            self.assertEqual(x1, x2)
+            self.assertEqual(y1, y2)
+
+class MersenneTwister_TestBasicOps(TestBasicOps):
+    gen = random.Random()
+
+    def test_referenceImplementation(self):
+        # Compare the python implementation with results from the original
+        # code.  Create 2000 53-bit precision random floats.  Compare only
+        # the last ten entries to show that the independent implementations
+        # are tracking.  Here is the main() function needed to create the
+        # list of expected random numbers:
+        #    void main(void){
+        #         int i;
+        #         unsigned long init[4]={61731, 24903, 614, 42143}, length=4;
+        #         init_by_array(init, length);
+        #         for (i=0; i<2000; i++) {
+        #           printf("%.15f ", genrand_res53());
+        #           if (i%5==4) printf("\n");
+        #         }
+        #     }
+        expected = [0.45839803073713259,
+                    0.86057815201978782,
+                    0.92848331726782152,
+                    0.35932681119782461,
+                    0.081823493762449573,
+                    0.14332226470169329,
+                    0.084297823823520024,
+                    0.53814864671831453,
+                    0.089215024911993401,
+                    0.78486196105372907]
+
+        self.gen.seed(61731L + (24903L<<32) + (614L<<64) + (42143L<<96))
+        actual = self.randomlist(2000)[-10:]
+        for a, e in zip(actual, expected):
+            self.assertAlmostEqual(a,e,places=14)
+
+    def test_strong_reference_implementation(self):
+        # Like test_referenceImplementation, but checks for exact bit-level
+        # equality.  This should pass on any box where C double contains
+        # at least 53 bits of precision (the underlying algorithm suffers
+        # no rounding errors -- all results are exact).
+        from math import ldexp
+
+        expected = [0x0eab3258d2231fL,
+                    0x1b89db315277a5L,
+                    0x1db622a5518016L,
+                    0x0b7f9af0d575bfL,
+                    0x029e4c4db82240L,
+                    0x04961892f5d673L,
+                    0x02b291598e4589L,
+                    0x11388382c15694L,
+                    0x02dad977c9e1feL,
+                    0x191d96d4d334c6L]
+
+        self.gen.seed(61731L + (24903L<<32) + (614L<<64) + (42143L<<96))
+        actual = self.randomlist(2000)[-10:]
+        for a, e in zip(actual, expected):
+            self.assertEqual(long(ldexp(a, 53)), e)
+
+    def test_long_seed(self):
+        # This is most interesting to run in debug mode, just to make sure
+        # nothing blows up.  Under the covers, a dynamically resized array
+        # is allocated, consuming space proportional to the number of bits
+        # in the seed.  Unfortunately, that's a quadratic-time algorithm,
+        # so don't make this horribly big.
+        seed = (1L << (10000 * 8)) - 1  # about 10K bytes
+        self.gen.seed(seed)
 
-# Ensure that the seed() method initializes all the hidden state.  In
-# particular, through 2.2.1 it failed to reset a piece of state used by
-# (and only by) the .gauss() method.
+class TestModule(unittest.TestCase):
+    def testMagicConstants(self):
+        self.assertAlmostEqual(random.NV_MAGICCONST, 1.71552776992141)
+        self.assertAlmostEqual(random.TWOPI, 6.28318530718)
+        self.assertAlmostEqual(random.LOG4, 1.38629436111989)
+        self.assertAlmostEqual(random.SG_MAGICCONST, 2.50407739677627)
 
-for seed in 1, 12, 123, 1234, 12345, 123456, 654321:
-    for seeder in random.seed, random.whseed:
-        seeder(seed)
-        x1 = random.random()
-        y1 = random.gauss(0, 1)
+    def test__all__(self):
+        # tests validity but not completeness of the __all__ list
+        defined = dict.fromkeys(dir(random))
+        for entry in random.__all__:
+            self.failUnless(entry in defined)
 
-        seeder(seed)
-        x2 = random.random()
-        y2 = random.gauss(0, 1)
+def test_main():
+    suite = unittest.TestSuite()
+    for testclass in (WichmannHill_TestBasicOps,
+                      MersenneTwister_TestBasicOps,
+                      TestModule):
+        suite.addTest(unittest.makeSuite(testclass))
+    test_support.run_suite(suite)
 
-        test_support.vereq(x1, x2)
-        test_support.vereq(y1, y2)
+if __name__ == "__main__":
+    test_main()