tests: verify pause vm also pauses emulation

This commit adds a regression test for correct emulation pausing.
The test will fail without the 'Pause VM' fix in the following
commits.

Signed-off-by: Adrian Catangiu <[email protected]>

Author: acatangiu

tests/integration_tests/build/test_coverage.py

@@ -23,7 +23,7 @@
 # this contains the frequency while on AMD it does not.
 # Checkout the cpuid crate. In the future other
 # differences may appear.
-COVERAGE_DICT = {"Intel": 84.9, "AMD": 84.8}
+COVERAGE_DICT = {"Intel": 84.8, "AMD": 84.7}
 PROC_MODEL = proc.proc_type()
 
 COVERAGE_MAX_DELTA = 0.05

tests/integration_tests/functional/test_pause_resume.py

@@ -2,12 +2,34 @@
 # SPDX-License-Identifier: Apache-2.0
 """Basic tests scenarios for snapshot save/restore."""
 
+import os
 import platform
 import pytest
 from framework.microvms import C3nano
+import host_tools.logging as log_tools
 import host_tools.network as net_tools  # pylint: disable=import-error
 
 
+def verify_net_emulation_paused(metrics):
+    """Verify net emulation is paused base on provided metrics."""
+    net_metrics = metrics['net']
+    assert net_metrics['rx_queue_event_count'] == 0
+    assert net_metrics['rx_partial_writes'] == 0
+    assert net_metrics['rx_tap_event_count'] == 0
+    assert net_metrics['rx_bytes_count'] == 0
+    assert net_metrics['rx_packets_count'] == 0
+    assert net_metrics['rx_fails'] == 0
+    assert net_metrics['rx_count'] == 0
+    assert net_metrics['tap_read_fails'] == 0
+    assert net_metrics['tap_write_fails'] == 0
+    assert net_metrics['tx_bytes_count'] == 0
+    assert net_metrics['tx_fails'] == 0
+    assert net_metrics['tx_count'] == 0
+    assert net_metrics['tx_packets_count'] == 0
+    assert net_metrics['tx_queue_event_count'] == 0
+    print(net_metrics)
+
+
 @pytest.mark.skipif(
     platform.machine() != "x86_64",
     reason="Not supported yet."
@@ -25,6 +47,13 @@ def test_pause_resume(bin_cloner_path):
     response = microvm.vm.patch(state='Resumed')
     assert microvm.api_session.is_status_bad_request(response.status_code)
 
+    # Configure metrics system and start microVM.
+    metrics_fifo_path = os.path.join(microvm.path, 'metrics_fifo')
+    metrics_fifo = log_tools.Fifo(metrics_fifo_path)
+    response = microvm.metrics.put(
+        metrics_path=microvm.create_jailed_resource(metrics_fifo.path)
+    )
+    assert microvm.api_session.is_status_no_content(response.status_code)
     microvm.start()
 
     ssh_connection = net_tools.SSHConnection(microvm.ssh_config)
@@ -37,6 +66,17 @@ def test_pause_resume(bin_cloner_path):
     response = microvm.vm.patch(state='Paused')
     assert microvm.api_session.is_status_no_content(response.status_code)
 
+    # Flush and reset metrics as they contain pre-pause data.
+    microvm.flush_metrics(metrics_fifo)
+
+    # Verify guest is no longer active.
+    exit_code, _, _ = ssh_connection.execute_command("ls")
+    assert exit_code != 0
+
+    # Verify emulation was indeed paused and no events from either
+    # guest or host side were handled.
+    verify_net_emulation_paused(microvm.flush_metrics(metrics_fifo))
+
     # Verify guest is no longer active.
     exit_code, _, _ = ssh_connection.execute_command("ls")
     assert exit_code != 0