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-rw-r--r--src/test/util_tests.cpp62
1 files changed, 62 insertions, 0 deletions
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index f56969cba6..1b0ccad511 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -261,4 +261,66 @@ BOOST_AUTO_TEST_CASE(util_IsHex)
BOOST_CHECK(!IsHex("0x0000"));
}
+BOOST_AUTO_TEST_CASE(util_seed_insecure_rand)
+{
+ // Expected results for the determinstic seed.
+ const uint32_t exp_vals[11] = { 91632771U,1889679809U,3842137544U,3256031132U,
+ 1761911779U, 489223532U,2692793790U,2737472863U,
+ 2796262275U,1309899767U,840571781U};
+ // Expected 0s in rand()%(idx+2) for the determinstic seed.
+ const int exp_count[9] = {5013,3346,2415,1972,1644,1386,1176,1096,1009};
+ int i;
+ int count=0;
+
+ seed_insecure_rand();
+
+ //Does the non-determistic rand give us results that look too like the determinstic one?
+ for (i=0;i<10;i++)
+ {
+ int match = 0;
+ uint32_t rval = insecure_rand();
+ for (int j=0;j<11;j++)match |= rval==exp_vals[j];
+ count += match;
+ }
+ // sum(binomial(10,i)*(11/(2^32))^i*(1-(11/(2^32)))^(10-i),i,0,4) ~= 1-1/2^134.73
+ // So _very_ unlikely to throw a false failure here.
+ BOOST_CHECK(count<=4);
+
+ for (int mod=2;mod<11;mod++)
+ {
+ int mask = 1;
+ // Really rough binomal confidence approximation.
+ int err = 30*10000./mod*sqrt((1./mod*(1-1./mod))/10000.);
+ //mask is 2^ceil(log2(mod))-1
+ while(mask<mod-1)mask=(mask<<1)+1;
+
+ count = 0;
+ //How often does it get a zero from the uniform range [0,mod)?
+ for (i=0;i<10000;i++)
+ {
+ uint32_t rval;
+ do{
+ rval=insecure_rand()&mask;
+ }while(rval>=(uint32_t)mod);
+ count += rval==0;
+ }
+ BOOST_CHECK(count<=10000/mod+err);
+ BOOST_CHECK(count>=10000/mod-err);
+ }
+
+ seed_insecure_rand(true);
+
+ for (i=0;i<11;i++)
+ {
+ BOOST_CHECK_EQUAL(insecure_rand(),exp_vals[i]);
+ }
+
+ for (int mod=2;mod<11;mod++)
+ {
+ count = 0;
+ for (i=0;i<10000;i++) count += insecure_rand()%mod==0;
+ BOOST_CHECK_EQUAL(count,exp_count[mod-2]);
+ }
+}
+
BOOST_AUTO_TEST_SUITE_END()