[link flap] add link flap pytest

Signed-off-by: Ying Xie <ying.xie@microsoft.com>

tests/common/platform/device_utils.py

@@ -0,0 +1,25 @@
+"""
+Helper script for fanout switch operations
+"""
+
+import logging
+
+def fanout_switch_port_lookup(fanout_switches, dut_port):
+    """
+        look up the fanout switch instance and the fanout switch port
+        connecting to the dut_port
+
+        Args:
+            fanout_switches (list FanoutHost): list of fanout switch
+                                               instaances.
+            dut_port (str): port name on the DUT
+
+        Returns:
+            None, None if fanout switch instance and port is not found
+            FanoutHost, Portname(str) if found
+    """
+    for _, fanout in fanout_switches.items():
+        if dut_port in fanout.host_to_fanout_port_map.keys():
+            return fanout, fanout.host_to_fanout_port_map[dut_port]
+
+    return None, None

tests/platform/test_link_flap.py

@@ -0,0 +1,80 @@
+import logging
+
+import pytest
+
+from common.platform.device_utils import fanout_switch_port_lookup
+from common.utilities import wait_until
+
+class TestLinkFlap:
+    def __init__(self):
+        self.ports_shutdown_by_test = set()
+
+
+    def __get_dut_if_facts(self, dut):
+        interface_facts = dut.interface_facts()
+        ansible_facts   = interface_facts['ansible_facts']
+        if_facts        = ansible_facts['ansible_interface_facts']
+
+        return if_facts
+
+
+    def __check_if_status(self, dut, dut_port, exp_state):
+        ifstate = self.__get_dut_if_facts(dut)[dut_port]
+        return ifstate['active'] == exp_state
+
+
+    def __toggle_one_port(self, dut, dut_port, fanout, fanout_port):
+        logging.info("Testing port toggle on {}".format(dut_port))
+
+        ifstate = self.__get_dut_if_facts(dut)[dut_port]
+        assert ifstate['active'], "dut port {} is down".format(dut_port)
+
+        logging.debug("Shutting down fanout switch {} port {} connecting to {}".format(fanout.hostname, fanout_port, dut_port))
+        self.ports_shutdown_by_test.add((fanout, fanout_port))
+        fanout.shutdown(fanout_port)
+        wait_until(30, 0.2, self.__check_if_status, dut, dut_port, False)
+        ifstate = self.__get_dut_if_facts(dut)[dut_port]
+        logging.debug("Interface fact  : {}".format(ifstate))
+        assert not ifstate['active'], "dut port {} didn't go down as expected".format(dut_port)
+
+        logging.debug("Bring up fanout switch {} port {} connecting to {}".format(fanout.hostname, fanout_port, dut_port))
+        fanout.no_shutdown(fanout_port)
+        wait_until(30, 0.2, self.__check_if_status, dut, dut_port, True)
+        ifstate = self.__get_dut_if_facts(dut)[dut_port]
+        logging.debug("Interface fact  : {}".format(ifstate))
+        assert ifstate['active'], "dut port {} didn't come up as expected".format(dut_port)
+        self.ports_shutdown_by_test.discard((fanout, fanout_port))
+
+
+    def __build_test_candidates(self, dut, fanouthosts):
+        if_facts = self.__get_dut_if_facts(dut)
+        candidates = []
+        for dut_port in if_facts.keys():
+            fanout, fanout_port = fanout_switch_port_lookup(fanouthosts, dut_port)
+
+            if not fanout or not fanout_port:
+                logging.info("Skipping port {} that is not found in connection graph".format(dut_port))
+            else:
+                candidates.append((dut_port, fanout, fanout_port))
+
+        return candidates
+
+
+    def run_link_flap_test(self, dut, fanouthosts):
+        candidates = self.__build_test_candidates(dut, fanouthosts)
+
+        try:
+            for dut_port, fanout, fanout_port in candidates:
+                self.__toggle_one_port(dut, dut_port, fanout, fanout_port)
+        finally:
+            logging.info("Restoring fanout switch ports that were shut down by test")
+            for fanout, fanout_port in self.ports_shutdown_by_test:
+                logging.debug("Restoring fanout switch {} port {} shut down by test".format(fanout.hostname, fanout_port))
+                fanout.no_shutdown(fanout_port)
+
+
+@pytest.mark.topology_agnostic
+@pytest.mark.platform_physical
+def test_link_flap(duthost, fanouthosts):
+    tlf = TestLinkFlap()
+    tlf.run_link_flap_test(duthost, fanouthosts)