Add unit test for ..get_start_of_next_voting_interval().

This functionality was covered only accidentally by our voting-test
code, and as such wasn't actually tested at all.  The tests that
called it made its coverage nondeterministic, depending on what time
of day you ran the tests.

Closes ticket 26014.

4 files changed, 67 insertions, 0 deletions

diff --git a/src/test/include.am b/src/test/include.am
index eb61d74893..43eaf1e239 100644
--- a/src/test/include.am
+++ b/src/test/include.am
@@ -171,6 +171,7 @@ src_test_test_SOURCES = \
 	src/test/test_util.c \
 	src/test/test_util_format.c \
 	src/test/test_util_process.c \
+	src/test/test_voting_schedule.c \
 	src/test/test_helpers.c \
 	src/test/test_dns.c \
 	src/test/testing_common.c \
diff --git a/src/test/test.c b/src/test/test.c
index b1e5345b3c..0ad33ec0c0 100644
--- a/src/test/test.c
+++ b/src/test/test.c
@@ -859,6 +859,7 @@ struct testgroup_t testgroups[] = {
   { "dir/", dir_tests },
   { "dir_handle_get/", dir_handle_get_tests },
   { "dir/md/", microdesc_tests },
+  { "dir/voting-schedule/", voting_schedule_tests },
   { "dos/", dos_tests },
   { "entryconn/", entryconn_tests },
   { "entrynodes/", entrynodes_tests },
diff --git a/src/test/test.h b/src/test/test.h
index 15965ccaf4..0cd0304629 100644
--- a/src/test/test.h
+++ b/src/test/test.h
@@ -265,6 +265,7 @@ extern struct testcase_t tortls_tests[];
 extern struct testcase_t util_tests[];
 extern struct testcase_t util_format_tests[];
 extern struct testcase_t util_process_tests[];
+extern struct testcase_t voting_schedule_tests[];
 extern struct testcase_t dns_tests[];
 extern struct testcase_t handle_tests[];
 extern struct testcase_t sr_tests[];
diff --git a/src/test/test_voting_schedule.c b/src/test/test_voting_schedule.c
new file mode 100644
index 0000000000..df6058b74f
--- /dev/null
+++ b/src/test/test_voting_schedule.c
@@ -0,0 +1,64 @@
+/* Copyright (c) 2018, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "orconfig.h"
+
+#include "or.h"
+#include "voting_schedule.h"
+
+#include "test.h"
+
+static void
+test_voting_schedule_interval_start(void *arg)
+{
+#define next_interval voting_schedule_get_start_of_next_interval
+  (void)arg;
+  char buf[ISO_TIME_LEN+1];
+
+  // Midnight UTC tonight (as I am writing this test)
+  const time_t midnight = 1525651200;
+  format_iso_time(buf, midnight);
+  tt_str_op(buf, OP_EQ, "2018-05-07 00:00:00");
+
+  /* Some simple tests with a 50-minute voting interval */
+
+  tt_i64_op(next_interval(midnight, 3000, 0), OP_EQ,
+            midnight+3000);
+
+  tt_i64_op(next_interval(midnight+100, 3000, 0), OP_EQ,
+            midnight+3000);
+
+  tt_i64_op(next_interval(midnight+3000, 3000, 0), OP_EQ,
+            midnight+6000);
+
+  tt_i64_op(next_interval(midnight+3001, 3000, 0), OP_EQ,
+            midnight+6000);
+
+  /* Make sure that we roll around properly at midnight */
+  tt_i64_op(next_interval(midnight+83000, 3000, 0), OP_EQ,
+            midnight+84000);
+
+  /* We start fresh at midnight UTC, even if there are leftover seconds. */
+  tt_i64_op(next_interval(midnight+84005, 3000, 0), OP_EQ,
+            midnight+86400);
+
+  /* Now try with offsets.  (These are only used for test networks.) */
+  tt_i64_op(next_interval(midnight, 3000, 99), OP_EQ,
+            midnight+99);
+
+  tt_i64_op(next_interval(midnight+100, 3000, 99), OP_EQ,
+            midnight+3099);
+
+ done:
+  ;
+#undef next_interval
+}
+
+#define VS(name,flags)                                          \
+  { #name, test_voting_schedule_##name, (flags), NULL, NULL }
+
+struct testcase_t voting_schedule_tests[] = {
+  VS(interval_start, 0),
+  END_OF_TESTCASES
+};
+