* Added unit test to executor to confirm spinning will trigger a timer callback.

Author: imdexsam

rclrs/src/executor.rs

@@ -86,3 +86,28 @@ impl SingleThreadedExecutor {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{spin_once, Context};
+
+    use super::*;
+
+    #[test]
+    fn spin_once_fires_timer() -> Result<(), RclrsError> {
+        let context = Context::new([])?;
+        let node = Node::new(&context, "test_spin_timer")?;
+
+        let callback_triggered = Arc::new(Mutex::new(false));
+        let callback_flag = Arc::clone(&callback_triggered);
+
+        let _timer = node.create_timer(Duration::from_secs(0), move |_| {
+            *callback_flag.lock().unwrap() = true;
+        })?;
+
+        spin_once(node, Some(Duration::ZERO))?;
+
+        assert!(*callback_triggered.lock().unwrap());
+        Ok(())
+    }
+}