test_config_fec_oper_mode: Set the fec_mode to align with the current…

… configuration of the interface. (#16360)

* Configure the fec_mode that interface is already configured for

* Fix a backslash

tests/platform_tests/test_intf_fec.py

@@ -1,6 +1,7 @@
 import logging
 import pytest
 
+from tests.common.helpers.assertions import pytest_assert
 from tests.common.utilities import skip_release, wait_until
 
 pytestmark = [
@@ -28,6 +29,15 @@ def is_supported_platform(duthost):
         pytest.skip("DUT has platform {}, test is not supported".format(duthost.facts['platform']))
 
 
+def get_fec_oper_mode(duthost, interface):
+    """
+    @Return: FEC operational mode for a specific interface
+    """
+    logging.info("Get output of '{} {}'".format("show interfaces fec status", interface))
+    fec_status = duthost.show_and_parse("show interfaces fec status {}".format(interface))
+    return fec_status[0].get('fec oper', '').lower()
+
+
 def test_verify_fec_oper_mode(duthosts, enum_rand_one_per_hwsku_frontend_hostname,
                               enum_frontend_asic_index, conn_graph_facts):
     """
@@ -52,9 +62,7 @@ def test_verify_fec_oper_mode(duthosts, enum_rand_one_per_hwsku_frontend_hostnam
 
             if presence == "present" and oper == "up" and speed in SUPPORTED_SPEEDS:
                 # Verify the FEC operational mode is valid
-                logging.info("Get output of '{} {}'".format("show interfaces fec status", intf['interface']))
-                fec_status = duthost.show_and_parse("show interfaces fec status {}".format(intf['interface']))
-                fec = fec_status[0].get('fec oper', '').lower()
+                fec = get_fec_oper_mode(duthost, intf['interface'])
                 if fec == "n/a":
                     pytest.fail("FEC status is N/A for interface {}".format(intf['interface']))
 
@@ -84,16 +92,18 @@ def test_config_fec_oper_mode(duthosts, enum_rand_one_per_hwsku_frontend_hostnam
             if presence == "not present" or oper != "up" or speed not in SUPPORTED_SPEEDS:
                 continue
 
-        config_status = duthost.command("sudo config interface fec {} rs"
-                                        .format(intf['interface']))
+        fec_mode = get_fec_oper_mode(duthost, intf['interface'])
+        if fec_mode == "n/a":
+            pytest.fail("FEC status is N/A for interface {}".format(intf['interface']))
+
+        config_status = duthost.command("sudo config interface fec {} {}"
+                                        .format(intf['interface'], fec_mode))
         if config_status:
-            wait_until(30, 2, 0, duthost.is_interface_status_up, intf["interface"])
+            pytest_assert(wait_until(30, 2, 0, duthost.is_interface_status_up, intf["interface"]),
+                          "Interface {} did not come up after configuring FEC mode".format(intf["interface"]))
             # Verify the FEC operational mode is restored
-            logging.info("Get output of '{} {}'".format("show interfaces fec status", intf['interface']))
-            fec_status = duthost.show_and_parse("show interfaces fec status {}".format(intf['interface']))
-            fec = fec_status[0].get('fec oper', '').lower()
-
-            if not (fec == "rs"):
+            post_fec = get_fec_oper_mode(duthost, intf['interface'])
+            if not (post_fec == fec_mode):
                 pytest.fail("FEC status is not restored for interface {}".format(intf['interface']))