1 files changed, 95 insertions, 0 deletions

diff --git a/timer/test/timer_test.c b/timer/test/timer_test.c
new file mode 100644
index 0000000..a220ead
--- /dev/null
+++ b/timer/test/timer_test.c
@@ -0,0 +1,95 @@
+#include "timer.h"
+
+#include <stdio.h>
+
+#include "test.h"
+
+// Sleep puts the calling thread to sleep for a time >= than the given time.
+TEST_CASE(sleep) {
+  const double sleep_time_sec = 0.1;
+
+  const time_point start = time_now();
+  time_sleep(sec_to_time_delta(sleep_time_sec));
+  const time_point end = time_now();
+
+  TEST_TRUE(time_delta_to_sec(time_diff(start, end)) >= sleep_time_sec);
+}
+
+// The timer starts as soon as it is created.
+TEST_CASE(start_on_new) {
+  const time_point test_start_time = time_now();
+  Timer timer = timer_make();
+  TEST_TRUE(time_delta_to_sec(time_diff(test_start_time, timer.start_time)) >=
+            0.0);
+}
+
+// Tick updates the timer's last tick time.
+TEST_CASE(tick_updates_last_tick_time) {
+  const double sleep_time_sec = 0.1;
+
+  Timer timer = timer_make();
+  time_sleep(sec_to_time_delta(sleep_time_sec));
+  timer_tick(&timer);
+
+  TEST_TRUE(time_delta_to_sec(time_diff(timer.start_time, timer.last_tick)) >=
+            sleep_time_sec);
+}
+
+// Tick updates the timer's delta time.
+TEST_CASE(tick_updates_delta_time) {
+  const double sleep_time_sec = 0.1;
+
+  Timer timer = timer_make();
+  time_sleep(sec_to_time_delta(sleep_time_sec));
+  timer_tick(&timer);
+
+  TEST_TRUE(time_delta_to_sec(timer.delta_time) >= sleep_time_sec);
+}
+
+// Tick leaves the timer's start time unchanged.
+TEST_CASE(tick_does_not_change_start_time) {
+  Timer timer = timer_make();
+  const time_point start_time = timer.start_time;
+  time_sleep(sec_to_time_delta(0.1));
+  timer_tick(&timer);
+  TEST_TRUE(time_delta_to_sec(time_diff(start_time, timer.start_time)) == 0.0);
+}
+
+// Start starts/restarts the timer and updates the timer's start time.
+TEST_CASE(start_restarts_start_time) {
+  const double sleep_time_seconds = 0.1;
+  Timer timer = timer_make();
+  const time_point start_time = timer.start_time;
+  time_sleep(sec_to_time_delta(sleep_time_seconds));
+  timer_start(&timer);
+  TEST_TRUE(time_delta_to_sec(time_diff(start_time, timer.start_time)) >=
+            sleep_time_seconds);
+}
+
+// Count the number of hundred-seconds in a second.
+TEST_CASE(count) {
+  Timer timer = timer_make();
+
+  int hundred_seconds = 0;
+  const time_point start = timer.start_time;
+  {
+    while (time_delta_to_sec(timer.running_time) <= 1.0) {
+      hundred_seconds++;
+      time_sleep(sec_to_time_delta(0.1));
+      timer_tick(&timer);
+      TEST_TRUE(time_delta_to_sec(timer.delta_time) >= 0.1);
+    }
+  }
+  const time_point end = time_now();
+
+  const double time_elapsed = time_delta_to_sec(time_diff(start, end));
+
+  TEST_EQUAL(hundred_seconds, 10);
+  TEST_TRUE(time_elapsed >= 1.0);
+}
+
+int main(int argc, const char** argv) {
+  (void)argc; // Unused.
+  printf("Usage: %s --unittest\n", argv[0]);
+  return 0;
+}