support more date formats in date

datetime.strptime doesn't support time zone like IST, and need specify
time format. Use dateutil.parser is easier.

lisa/tools/date.py

@@ -1,5 +1,7 @@
 from datetime import datetime
 
+from dateutil.parser import parser
+
 from lisa.executable import Tool
 from lisa.util import LisaException
 
@@ -18,6 +20,4 @@ class Date(Tool):
             raise LisaException(
                 f"'Date' return non-zero exit code: {command_result.stderr}"
             )
-        # Mon Nov 23 00:21:02 UTC 2020
-        result = datetime.strptime(command_result.stdout, "%a %b %d %H:%M:%S %Z %Y")
-        return result
+        return parser().parse(command_result.stdout)

lisa/tools/reboot.py

@@ -34,14 +34,16 @@ class Reboot(Tool):
         # The reboot will wait forever.
         # in this case, verify the time is wait enough to prevent this problem.
         date = self.node.tools[Date]
-        current_delta = date.current() - current_boot_time
+        # boot time has no tzinfo, so remove from date result to avoid below error.
+        # TypeError: can't subtract offset-naive and offset-aware datetimes
+        current_delta = date.current().replace(tzinfo=None) - current_boot_time
         self._log.debug(f"delta time since last boot: {current_delta}")
         while current_delta < timedelta(minutes=1):
             # wait until one minute
             wait_seconds = 60 - current_delta.seconds + 1
             self._log.debug(f"waiting {wait_seconds} seconds before rebooting")
             sleep(wait_seconds)
-            current_delta = date.current() - current_boot_time
+            current_delta = date.current().replace(tzinfo=None) - current_boot_time
 
         self._log.debug(f"rebooting with boot time: {last_boot_time}")
         try:

lisa/tools/who.py

@@ -1,6 +1,8 @@
 import re
 from datetime import datetime
 
+from dateutil.parser import parser
+
 from lisa.executable import Tool
 from lisa.util import LisaException, get_matched_str
 
@@ -23,11 +25,5 @@ class Who(Tool):
                 f"'last' return non-zero exit code: {command_result.stderr}"
             )
         datetime_output = get_matched_str(command_result.stdout, self.last_time_pattern)
-        try:
-            result = datetime.fromisoformat(datetime_output)
-        except ValueError:
-            # ValueError: Invalid isoformat string: 'Nov 10 20:54'
-            datetime_with_year = f"{datetime_output} {datetime.utcnow().year}"
-            result = datetime.strptime(datetime_with_year, "%b %d %H:%M %Y")
 
-        return result
+        return parser().parse(datetime_output)