Correctly initialise clock type for ROSClocks instantiated directly

Author: dhood

rclpy/rclpy/clock.py

@@ -60,6 +60,9 @@ def now(self):
 
 class ROSClock(Clock):
 
+    def __new__(cls):
+        return super().__new__(Clock, clock_type=ClockType.ROS_TIME)
+
     @property
     def ros_time_is_active(self):
         return _rclpy.rclpy_clock_get_ros_time_override_is_enabled(self._clock_handle)

rclpy/test/test_clock.py

@@ -38,6 +38,10 @@ def test_clock_construction(self):
         assert clock.clock_type == ClockType.ROS_TIME
         assert isinstance(clock, ROSClock)
 
+        # Direct instantiation of a ROSClock is also possible.
+        clock = ROSClock()
+        assert clock.clock_type == ClockType.ROS_TIME
+
     def test_clock_now(self):
         # System time should be roughly equal to time.time()
         # There will still be differences between them, with the bound depending on the scheduler.