test(signal): sleep to avoid race condition

The unit test is asserting that the metrics are increased, however the
signal delivery is asynchronous so it could sometimes happen that a
metric (usually the last one) isn't increased it.
By adding a 100ms wait, it would be very unlikely to happen.

Signed-off-by: Riccardo Mancini <[email protected]>

Author: Manciukic

src/vmm/src/signal_handler.rs

@@ -174,6 +174,7 @@ pub fn register_signal_handlers() -> vmm_sys_util::errno::Result<()> {
 #[cfg(test)]
 mod tests {
     #![allow(clippy::undocumented_unsafe_blocks)]
+    use std::time::Duration;
     use std::{process, thread};
 
     use libc::syscall;
@@ -229,6 +230,9 @@ mod tests {
         });
         child.join().unwrap();
 
+        // signal delivery is asynchronous so wait a little to avoid race conditions
+        thread::sleep(Duration::from_millis(100));
+
         assert!(METRICS.signals.sigbus.fetch() >= 1);
         assert!(METRICS.signals.sigsegv.fetch() >= 1);
         assert!(METRICS.signals.sigxfsz.fetch() >= 1);