added port autoneg test support for testbeds with AOS fanouts (#5206)

What is the motivation for this PR?
Port autoneg tests execute fanout commands via a common class FanoutHost which in turn delegates commands to OS specific impl. For now AOS class does not have methods required by port autoneg test. The PR resolves the issue

How did you do it?
Implemented methods tests require

How did you verify/test it?
py.test --inventory=../ansible/lab,../ansible/veos --testbed_file=../ansible/testbed.csv --module-path=../ansible/library -v -rA --topology=t1,any platform_tests/test_auto_negotiation.py

Author: antonptashnik

tests/common/devices/aos.py

@@ -2,19 +2,31 @@
 import logging
 import os
 
+from tests.common.devices.base import AnsibleHostBase
+import re
 
-class AosHost():
+def _raise_err(msg):
+        raise Exception(msg)
+
+class AosHost(AnsibleHostBase):
     """
     @summary: Class for Accton switch
     For running ansible module on the Accton switch
     """
 
     def __init__(self, ansible_adhoc, hostname, user, passwd, gather_facts=False):
+        AnsibleHostBase.__init__(self, ansible_adhoc, hostname)
         self.hostname = hostname
-        self.user = user
-        self.passwd = passwd
         self.localhost = ansible_adhoc(inventory='localhost', connection='local', host_pattern="localhost")["localhost"]
 
+        self.admin_conn_props = {
+            'ansible_connection': 'network_cli',
+            'ansible_network_os':'aos',
+            'ansible_become_method': 'enable',
+            'ansible_user': user,
+            'ansible_password': passwd
+        }
+
     def _exec_jinja_template(self, task_name, jinja_template):
         inventory = 'lab'
         ansible_root = '../ansible/'
@@ -97,3 +109,86 @@ def exec_template(self, ansible_root, ansible_playbook, inventory, **kwargs):
 
         if res["localhost"]["rc"] != 0:
             raise Exception("Unable to execute template\n{}".format(res["localhost"]["stdout"]))
+
+    # delegate AOS related commands to Ansible
+    def __getattr__(self, module_name):
+        if not module_name.startswith('aos_'):
+            return None
+        self.host.options['variable_manager'].extra_vars.update(self.admin_conn_props)
+        return super(AosHost, self).__getattr__(module_name)
+
+    def _has_cli_cmd_failed(self, cmd_output_obj):
+        return 'failed' in cmd_output_obj and cmd_output_obj['failed']
+
+    def cli_command(self, cmd):
+        return self.aos_command(commands=[cmd])['stdout'][0]
+
+    def get_auto_negotiation_mode(self, port):
+        return self.get_speed(port) == 'Auto'
+
+    def set_auto_negotiation_mode(self, port, enabled):
+        if self.get_auto_negotiation_mode(port) == enabled:
+            return True
+        if enabled:
+            out = self.aos_config(
+                lines=['negotiation'],
+                parents=['interface {}'.format(port)])
+        else:
+            out = self.aos_config(
+                lines=['no negotiation'],
+                parents=['interface {}'.format(port)])
+        return not self._has_cli_cmd_failed(out)
+    
+    def get_speed(self, port):
+        output = self.cli_command('show interfaces status {}'.format(port))
+
+        found_txt = extract_val('Speed-duplex', output)
+        if found_txt is None:
+            _raise_err('Not able to extract interface %s speed from output: %s' % (port, output))
+
+        return speed_gb_to_mb(found_txt)
+
+    def get_supported_speeds(self, port):
+        """Get supported speeds for a given interface
+
+        Args:
+            interface_name (str): Interface name
+
+        Returns:
+            list: A list of supported speed strings or None
+        """
+        output = self.cli_command('show interfaces status {}'.format(port))
+        found_txt = extract_val('Capabilities', output)
+
+        if found_txt is None:
+            _raise_err('Failed to find port speeds list in output: %s' % output)
+
+        speed_list = found_txt.split(',')
+        return list(map(speed_gb_to_mb, speed_list))
+
+    def set_speed(self, interface_name, speed):
+        
+        if not speed:
+            # other set_speed implementations advertise port speeds when speed=None
+            # but in AOS autoneg activation and speeds advertisement is done via a single CLI cmd
+            # so this branch left nop intentionally
+            return True
+        speed = speed_mb_to_gb(speed)
+        out = self.aos_config(
+                lines=['speed {}'.format(speed)],
+                parents='interface %s' % interface_name)
+        return not self._has_cli_cmd_failed(out)
+
+def speed_gb_to_mb(speed):
+    res = re.search(r'(\d+)(\w)', speed)
+    if not res:
+        return speed
+    speed = res.groups()[0]
+    return speed + '000'
+
+def speed_mb_to_gb(val):
+    return '{}Gfull'.format(int(val) // 1000)
+
+def extract_val(prop_name, output):
+    found_txt = re.search(r'{}\s+:\s+(.+)'.format(prop_name), output)
+    return found_txt.groups()[0] if found_txt else None