[post-test] Add a param to specify show tech since in post-test (sonic-net#9771)

What is the motivation for this PR?
Add a parameter to specify show tech since in post-test. The default value is yesterday, which keeps the same behavior as current code.
To collect show tech result of all time spans, please specify --posttest_show_tech_since='-1hour'.

How did you do it?
Add parameter --posttest_show_tech_since in conftest.py and use it in test_collect_techsupport.

How did you verify/test it?
Verified on physical DUT with below parameters:
* Do not specify --posttest_show_tech_since
* Empty string: --posttest_show_tech_since=
* Collect all time span: --posttest_show_tech_since='@0'
* Collect since 1 hour ago: --posttest_show_tech_since='-1hour'

Signed-off-by: Zhijian Li <[email protected]>

Author: lizhijianrd

tests/conftest.py

@@ -149,6 +149,14 @@ def pytest_addoption(parser):
                      help="Specify the url of the saithrift package to be installed on the ptf "
                           "(should be http://<serverip>/path/python-saithrift_0.9.4_amd64.deb")
 
+    #########################
+    #   post-test options   #
+    #########################
+    parser.addoption("--posttest_show_tech_since", action="store", default="yesterday",
+                     help="collect show techsupport since <date>. <date> should be a string which can "
+                          "be parsed by bash command 'date --d <date>'. Default value is yesterday. "
+                          "To collect all time spans, please use '@0' as the value.")
+
     ############################
     #  keysight ixanvl options #
     ############################

tests/test_posttest.py

@@ -14,20 +14,23 @@
 ]
 
 
-def test_collect_techsupport(duthosts, enum_dut_hostname):
+def test_collect_techsupport(request, duthosts, enum_dut_hostname):
+    since = request.config.getoption("--posttest_show_tech_since")
+    if since == '':
+        since = 'yesterday'
     duthost = duthosts[enum_dut_hostname]
     """
     A util for collecting techsupport after tests.
 
     Since nightly test on Jenkins will do a cleanup at the beginning of tests,
     we need a method to save history logs and dumps. This util does the job.
     """
-    logger.info("Collecting techsupport since yesterday")
+    logger.info("Collecting techsupport since {}".format(since))
     # Because Jenkins is configured to save artifacts from tests/logs,
     # and this util is mainly designed for running on Jenkins,
     # save path is fixed to logs for now.
     TECHSUPPORT_SAVE_PATH = 'logs/'
-    out = duthost.command("generate_dump -s yesterday", module_ignore_errors=True)
+    out = duthost.command("show techsupport --since {}".format(since), module_ignore_errors=True)
     if out['rc'] == 0:
         tar_file = out['stdout_lines'][-1]
         duthost.fetch(src=tar_file, dest=TECHSUPPORT_SAVE_PATH, flat=True)