1 files changed, 30 insertions, 0 deletions
diff --git a/lib/ccan/tally/test/run-mean.c b/lib/ccan/tally/test/run-mean.c
new file mode 100644
index 0000000000..b43dea6b28
--- /dev/null
+++ b/lib/ccan/tally/test/run-mean.c
@@ -0,0 +1,30 @@
+#include <ccan/tally/tally.c>
+#include <ccan/tap/tap.h>
+
+int main(void)
+{
+	int i;
+	struct tally *tally = tally_new(0);
+	ssize_t min, max;
+
+	max = (ssize_t)~(1ULL << (sizeof(max)*CHAR_BIT - 1));
+	min = (ssize_t)(1ULL << (sizeof(max)*CHAR_BIT - 1));
+
+	plan_tests(100 + 100);
+	/* Simple mean test: should always be 0. */
+	for (i = 0; i < 100; i++) {
+		tally_add(tally, i);
+		tally_add(tally, -i);
+		ok1(tally_mean(tally) == 0);
+	}
+
+	/* Works for big values too... */
+	for (i = 0; i < 100; i++) {
+		tally_add(tally, max - i);
+		tally_add(tally, min + 1 + i);
+		ok1(tally_mean(tally) == 0);
+	}
+
+	free(tally);
+	return exit_status();
+}