test(net): add retry in test_tap_offload

This test has been flaky for a while, where sometimes the file is empty.
As we're just interested that the message got delivered, not that the
file was created in a timely manner, I'm adding a small retry.

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

Author: Manciukic

tests/integration_tests/functional/test_net.py

@@ -118,5 +118,13 @@ def test_tap_offload(uvm_any):
     vm.netns.check_output(f"python3 ./host_tools/udp_offload.py {vm.ssh.host} {port}")
 
     # Check that the server received the message
-    ret = vm.ssh.run(f"sync ; cat {out_filename}")
+    # Allow for some delay due to the asynchronous nature of the test
+    retry = 10
+    while retry > 0:
+        ret = vm.ssh.run(f"sync ; cat {out_filename}")
+        if ret.stdout.strip():
+            break
+        time.sleep(0.1)
+        retry -= 1
+
     assert ret.stdout == message, f"{ret.stdout=} {ret.stderr=}"