[GCU E2E test] add stop pfcwd test (#7308)

Author: isabelmsft

tests/generic_config_updater/test_pfcwd_interval.py

@@ -120,13 +120,52 @@ def get_new_interval(duthost, is_valid):
         return min(detection_time, restoration_time) + 10
 
 
+def test_stop_pfcwd(duthost, ensure_dut_readiness):
+    start_pfcwd = duthost.shell('config pfcwd start_default')
+    pytest_assert(not start_pfcwd['rc'], "Failed to start default pfcwd config")
+    pfcwd_config = duthost.shell("show pfcwd config")
+    pytest_assert(not pfcwd_config['rc'], "Unable to read pfcwd config")
+
+    for line in pfcwd_config['stdout_lines']:
+        if line.startswith('Ethernet'):
+            interface = line.split()[0]
+            break
+    else:
+        pytest_assert(False, "No interface found running pfcwd - unable to run test")
+
+    json_patch = [
+        {
+            "op": "remove",
+            "path": "/PFC_WD/{}/detection_time".format(interface),
+        },
+        {
+            "op": "remove",
+            "path": "/PFC_WD/{}/restoration_time".format(interface),
+        },
+        {
+            "op": "remove",
+            "path": "/PFC_WD/{}/action".format(interface)
+        }
+    ]
+
+    try:
+        tmpfile = generate_tmpfile(duthost)
+        output = apply_patch(duthost, json_data=json_patch, dest_file=tmpfile)
+        expect_op_success(duthost, output)
+        pfcwd_updated_config = duthost.shell("show pfcwd config")
+        pytest_assert(not pfcwd_config['rc'], "Unable to read updated pfcwd config")
+        pytest_assert(interface not in pfcwd_updated_config['stdout'].split(), "pfcwd unexpectedly still running on interface {}".format(interface))
+    finally:
+        delete_tmpfile(duthost, tmpfile)
+
+
 @pytest.mark.parametrize("operation", ["add", "replace"])
 @pytest.mark.parametrize("field_pre_status", ["existing", "nonexistent"])
 @pytest.mark.parametrize("is_valid_config_update", [True, False])
 def test_pfcwd_interval_config_updates(duthost, ensure_dut_readiness, operation, field_pre_status, is_valid_config_update):
     new_interval = get_new_interval(duthost, is_valid_config_update)
 
-    operation_to_new_value_map = {"add": "{}".format(new_interval), "replace": "{}".format(new_interval), "remove": ""}
+    operation_to_new_value_map = {"add": "{}".format(new_interval), "replace": "{}".format(new_interval)}
     detection_time, restoration_time = get_detection_restoration_times(duthost)
     pre_status = max(detection_time, restoration_time)
     field_pre_status_to_value_map = {"existing": "{}".format(pre_status), "nonexistent": ""}