lib: Add test for rng

src/lib/Makefile.am

@@ -394,6 +394,7 @@ test_lib_SOURCES = \
 	test-primes.c \
 	test-printf-format-fix.c \
 	test-priorityq.c \
+	test-random.c \
 	test-seq-range-array.c \
 	test-stats-dist.c \
 	test-str.c \
@@ -414,7 +415,7 @@ test_headers = \
 	test-lib.h \
 	test-lib.inc
 
-test_lib_LDADD = $(test_libs)
+test_lib_LDADD = $(test_libs) -lm
 test_lib_DEPENDENCIES = $(test_libs)
 
 check-local:

src/lib/test-lib.inc

@@ -71,6 +71,7 @@ TEST(test_primes)
 TEST(test_printf_format_fix)
 FATAL(fatal_printf_format_fix)
 TEST(test_priorityq)
+TEST(test_random)
 TEST(test_seq_range_array)
 TEST(test_stats_dist)
 TEST(test_str)

src/lib/test-random.c

@@ -0,0 +1,40 @@
+/* Copyright (c) 2018 Dovecot authors, see the included COPYING file */
+
+#include "test-lib.h"
+#include "stats-dist.h"
+#include "randgen.h"
+#include <math.h>
+
+#define TEST_RAND_SIZE_MEDIAN 100000.0
+
+static void test_random_median(void)
+{
+	uint64_t tmp;
+	double median, average;
+
+	struct stats_dist *s = stats_dist_init_with_size(TEST_RAND_SIZE_MEDIAN);
+	test_begin("test_random (median & average)");
+	for(unsigned int i = 0; i < TEST_RAND_SIZE_MEDIAN; i++) {
+		uint64_t value;
+		value = i_rand_limit(TEST_RAND_SIZE_MEDIAN);
+		stats_dist_add(s, value);
+	}
+	tmp = stats_dist_get_median(s);
+
+	/* median should be 0.5 +-2% */
+	median = (double)tmp / TEST_RAND_SIZE_MEDIAN;
+	test_assert(fabs(median - 0.5) < 0.01);
+
+	/* average should be 0.5 +- %2 */
+	average = stats_dist_get_avg(s) / TEST_RAND_SIZE_MEDIAN;
+
+	test_assert(fabs(average - 0.5) < 0.01);
+
+	stats_dist_deinit(&s);
+	test_end();
+}
+
+void test_random(void)
+{
+	test_random_median();
+}