timer: add assertions to test

2 files changed, 25 insertions, 0 deletions

diff --git a/test/timer.cc b/test/timer.cc
index 5ac169c..3b5b5ac 100644
--- a/test/timer.cc
+++ b/test/timer.cc
@@ -1,5 +1,6 @@
 #include <timer.h>
 #include <unistd.h>
+#include <cassert>
 #include <cstdio>
 
 int main() {
@@ -15,6 +16,9 @@ int main() {
     const timer::scoped_timer kS{t};
     usleep(100 * 1000);
   }
+  assert(100000 < t.as_usec() && t.as_usec() < 101000);
+  assert(100 < t.as_msec() && t.as_msec() < 101);
+  assert(0.100 < t.as_sec() && t.as_sec() < 0.101);
   kShowTime();
 
   {
@@ -22,6 +26,20 @@ int main() {
     const timer::scoped_timer kS{t};
     usleep(500 * 1000);
   }
+  assert(600000 < t.as_usec() && t.as_usec() < 601000);
+  assert(600 < t.as_msec() && t.as_msec() < 601);
+  assert(0.600 < t.as_sec() && t.as_sec() < 0.601);
+  kShowTime();
+
+  t.reset();
+  {
+    puts("Sleep 200ms");
+    timer::scoped_timer s{t};
+    usleep(200 * 1000);
+  }
+  assert(200000 < t.as_usec() && t.as_usec() < 201000);
+  assert(200 < t.as_msec() && t.as_msec() < 201);
+  assert(0.200 < t.as_sec() && t.as_sec() < 0.201);
   kShowTime();
 
   return 0;
diff --git a/timer.h b/timer.h
index ce0e629..15e0497 100644
--- a/timer.h
+++ b/timer.h
@@ -2,6 +2,7 @@
 #include <ctime>
 
 namespace timer {
+/// A minimal Linux watch clock.
 struct timer {
   constexpr timer() = default;
 
@@ -17,6 +18,10 @@ struct timer {
                (end.tv_nsec - m_start.tv_nsec);
   }
 
+  constexpr void reset() {
+    m_nanos = 0;
+  }
+
   constexpr double as_sec() const {
     return as_msec() / 1000.0;
   }
@@ -36,6 +41,8 @@ struct timer {
   std::uint64_t m_nanos{0};
 };
 
+/// A scoped timer to automatically start / stop a watch clock in the scope the
+/// scoped_timer lives.
 struct scoped_timer {
   explicit scoped_timer(timer& t) : m_timer(t) {
     m_timer.start();