add ptfhost check statement to prevent failure on test_posttest.py (#…

…14783)

PTFHost can be None in some cases (eg. ixia) and this was not handled correctly in test_collect_ptf_logs. Add ptfhost check to prevent error caused by None value.

PTFHost can be None in some cases (eg. ixia) and this was not handled correctly in test_collect_ptf_logs. Add ptfhost check to prevent error caused by None value.

Description of PR
Summary:
PTFHost can be None in some cases (eg. ixia) and this was not handled correctly in test_collect_ptf_logs. Add ptfhost check to prevent error caused by None value.

Approach
What is the motivation for this PR?
Resolve unexpected error during log collection

How did you do it?
check for None value

co-authorized by: jianquanye@microsoft.com

tests/test_posttest.py

@@ -92,6 +92,8 @@ def test_enable_startup_tsa_tsb_service(duthosts, localhost):
 
 
 def test_collect_ptf_logs(ptfhost):
+    if ptfhost is None:
+        return
     log_files = ptfhost.shell('ls /tmp/*.log')['stdout'].split()
     if not os.path.exists('logs/ptf'):
         os.makedirs('logs/ptf')