[pfcwd] Fix the return code in invalid case (sonic-net#1691)

Signed-off-by: Neetha John <nejo@microsoft.com>

Fixes sonic-net#1690

What I did
Set the correct return code when pfcwd command is specified with invalid options

How to verify it
Modified the unit test to check for the correct return code and ran them and they passed

pfcwd/main.py

@@ -242,7 +242,7 @@ def start(self, action, restoration_time, ports, detection_time):
             click.echo("Failed to run command, invalid options:")
             for opt in invalid_ports:
                 click.echo(opt)
-            exit()
+            exit(1)
         self.start_cmd(action, restoration_time, ports, detection_time)
 
 

tests/pfcwd_test.py

@@ -255,7 +255,7 @@ def test_pfcwd_start_ports_invalid(self):
             obj=db
         )
         print(result.output)
-        assert result.exit_code == 0
+        assert result.exit_code == 1
         assert result.output == pfcwd_show_start_config_output_fail
 
     @classmethod
@@ -447,7 +447,7 @@ def test_pfcwd_start_ports_masic_invalid(self):
             obj=db
         )
         print(result.output)
-        assert result.exit_code == 0
+        assert result.exit_code == 1
         assert result.output == show_pfc_config_start_fail
 
         # get config after the command, config shouldn't change
@@ -500,4 +500,4 @@ def teardown_class(cls):
         import mock_tables.mock_single_asic
         importlib.reload(mock_tables.mock_single_asic)
         import pfcwd.main
-        importlib.reload(pfcwd.main)
+        importlib.reload(pfcwd.main)