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diff --git a/pipermail/pycrypto/2011q1/000380.html b/pipermail/pycrypto/2011q1/000380.html new file mode 100644 index 0000000..518de82 --- /dev/null +++ b/pipermail/pycrypto/2011q1/000380.html @@ -0,0 +1,129 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML> + <HEAD> + <TITLE> [pycrypto] Issue with the new random.choice() unit test + </TITLE> + <LINK REL="Index" HREF="index.html" > + <LINK REL="made" HREF="mailto:pycrypto%40lists.dlitz.net?Subject=%5Bpycrypto%5D%20Issue%20with%20the%20new%20random.choice%28%29%20unit%20test&In-Reply-To=4D2385B2.2050406%40gmx.li"> + <META NAME="robots" CONTENT="index,nofollow"> + <META http-equiv="Content-Type" content="text/html; charset=us-ascii"> + <LINK REL="Previous" HREF="000379.html"> + <LINK REL="Next" HREF="000381.html"> + </HEAD> + <BODY BGCOLOR="#ffffff"> + <H1>[pycrypto] Issue with the new random.choice() unit test</H1> + <B>Lorenz Quack</B> + <A HREF="mailto:pycrypto%40lists.dlitz.net?Subject=%5Bpycrypto%5D%20Issue%20with%20the%20new%20random.choice%28%29%20unit%20test&In-Reply-To=4D2385B2.2050406%40gmx.li" + TITLE="[pycrypto] Issue with the new random.choice() unit test">don at amberfisharts.com + </A><BR> + <I>Tue Jan 4 17:24:14 CST 2011</I> + <P><UL> + <LI>Previous message: <A HREF="000379.html">[pycrypto] Issue with the new random.choice() unit test +</A></li> + <LI>Next message: <A HREF="000381.html">[pycrypto] Issue with the new random.choice() unit test +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#380">[ date ]</a> + <a href="thread.html#380">[ thread ]</a> + <a href="subject.html#380">[ subject ]</a> + <a href="author.html#380">[ author ]</a> + </LI> + </UL> + <HR> +<!--beginarticle--> +<PRE>Well, this problem exist in all your random test although it is indeed +unlikely that one will hit the others. +I personally wouldn't worry to much about the exact distribution of most +random tests. They all use random.randrange which in turn uses getrandbits. +So if you want to go for *real* tests those functions should be the focus. +Although proper test for the others functions would of course also be good +I personally would settle for simple sanity checks (i.e., just increase the +seq size or wrap the part with a try-except block in which you repeat the test. +If it fails again raise an exception) + +By the way: + * You don't need to create the seq randomly or do you? wouldn't range(500) suffice? + * I find the way you fixed the shuffle function rather odd (good catch, though) + my suggestion would be + for i in xrange(len(x)): + p = self.randrange(len(items)) + x[i] = items[p] + del items[p] + or even shorter + for i in xrange(len(x)): + x[i] = items.pop(self.randrange(len(items))) + +sincerely yours, +//Lorenz + + +On 01/04/2011 09:40 PM, Thorsten Behrens wrote: +><i> I have introduced a unit test in test_random.py that has too high a rate +</I>><i> of failure. Specifically, this: +</I>><i> +</I>><i> # Test choice +</I>><i> seq = [] +</I>><i> for i in range(500): # seed the sequence +</I>><i> seq[i:] = [random.getrandbits(32)] +</I>><i> x = random.choice(seq) +</I>><i> y = random.choice(seq) +</I>><i> self.assertNotEqual(x, y) +</I>><i> +</I>><i> just produced a FAIL: +</I>><i> +</I>><i> FAIL: runTest (Crypto.SelfTest.Random.test_random.SimpleTest) +</I>><i> Crypto.Random.new() +</I>><i> ---------------------------------------------------------------------- +</I>><i> Traceback (most recent call last): +</I>><i> File "build\lib.win-amd64-2.7\Crypto\SelfTest\Random\test_random.py", +</I>><i> line 103, in runTest +</I>><i> self.assertNotEqual(x, y) +</I>><i> AssertionError: 1793595220L == 1793595220L +</I>><i> +</I>><i> +</I>><i> Well darn. I guess saying "hey it's a 1 in 500 chance, it'll never +</I>><i> fail!" is indeed naive. What would be a less naive test, then? I am +</I>><i> thinking seeding a much smaller seq, and then running choice many times, +</I>><i> counting collisions each time, and getting some form of expected value +</I>><i> with an expected precision from that. It's been very long since I've +</I>><i> done stochastic stuff, however. Before I screw this up further: Concrete +</I>><i> suggestions on how to fix this unit test? +</I>><i> +</I>><i> Thanks! +</I>><i> Thorsten +</I> +</PRE> + + + + + + + + + + + + + + +<!--endarticle--> + <HR> + <P><UL> + <!--threads--> + <LI>Previous message: <A HREF="000379.html">[pycrypto] Issue with the new random.choice() unit test +</A></li> + <LI>Next message: <A HREF="000381.html">[pycrypto] Issue with the new random.choice() unit test +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#380">[ date ]</a> + <a href="thread.html#380">[ thread ]</a> + <a href="subject.html#380">[ subject ]</a> + <a href="author.html#380">[ author ]</a> + </LI> + </UL> + +<hr> +<a href="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">More information about the pycrypto +mailing list</a><br> +</body></html> |