Add prints in tests

Author: nviennot

src/process/process_group.rs

@@ -322,6 +322,7 @@ mod test {
 
         drop(pgrp);
 
+        println!("elapsed time {}ms", start_time.elapsed().as_millis());
         assert!(start_time.elapsed().as_millis() > 1000);
 
         Ok(())
@@ -337,6 +338,7 @@ mod test {
 
         pgrp.wait_for_success()?;
 
+        println!("elapsed time {}ms", start_time.elapsed().as_millis());
         assert!(start_time.elapsed().as_secs() < 1000);
 
         Ok(())