fix: Periodic timers were being removed.

Author: kcexn

include/net/timers/impl/timers_impl.hpp

@@ -251,7 +251,7 @@ auto timers<Interrupt>::resolve() -> duration
     if (event.period.count() == 0)
       event.armed.clear();
 
-    return event.armed.test();
+    return !event.armed.test();
   });
 
   return with_lock(std::unique_lock(mtx_), [&] {

tests/test_timers.cpp

@@ -77,4 +77,16 @@ TEST(TimersTests, ReuseTimerID)
   auto timer1 = timers.add(100, [](timer_id) {});
   EXPECT_EQ(timer0, timer1);
 }
+
+TEST(TimersTests, PeriodicTimer)
+{
+  using namespace std::chrono;
+
+  auto timers = timers_type();
+  auto timer0 = timers.add(100, [](timer_id) {}, 100);
+  ASSERT_EQ(timer0, 0);
+  std::this_thread::sleep_for(milliseconds(1));
+  auto next = timers.resolve();
+  EXPECT_NE(next.count(), -1);
+}
 // NOLINTEND