kunit: tool: fix minor typing issue with None status

The code to handle aggregating statuses didn't check that the status
actually got set to some non-None value.
Default the value to SUCCESS instead of adding a bunch of `is None`
checks.

This sorta follows the precedent in commit 3fc4825 ("kunit: Don't
fail test suites if one of them is empty").

Also slightly simplify the code and add type annotations.

Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: dlatypov

tools/testing/kunit/kunit_parser.py

@@ -12,13 +12,13 @@
 from datetime import datetime
 from enum import Enum, auto
 from functools import reduce
-from typing import Iterator, List, Optional, Tuple
+from typing import Iterable, Iterator, List, Optional, Tuple
 
 TestResult = namedtuple('TestResult', ['status','suites','log'])
 
 class TestSuite(object):
 	def __init__(self) -> None:
-		self.status = None  # type: Optional[TestStatus]
+		self.status = TestStatus.SUCCESS
 		self.name = ''
 		self.cases = []  # type: List[TestCase]
 
@@ -30,7 +30,7 @@ def __repr__(self) -> str:
 
 class TestCase(object):
 	def __init__(self) -> None:
-		self.status = None  # type: Optional[TestStatus]
+		self.status = TestStatus.SUCCESS
 		self.name = ''
 		self.log = []  # type: List[str]
 
@@ -224,12 +224,11 @@ def parse_ok_not_ok_test_suite(lines: List[str],
 	else:
 		return False
 
-def bubble_up_errors(to_status, status_container_list) -> TestStatus:
-	status_list = map(to_status, status_container_list)
-	return reduce(max_status, status_list, TestStatus.SUCCESS)
+def bubble_up_errors(statuses: Iterable[TestStatus]) -> TestStatus:
+	return reduce(max_status, statuses, TestStatus.SUCCESS)
 
 def bubble_up_test_case_errors(test_suite: TestSuite) -> TestStatus:
-	max_test_case_status = bubble_up_errors(lambda x: x.status, test_suite.cases)
+	max_test_case_status = bubble_up_errors(x.status for x in test_suite.cases)
 	return max_status(max_test_case_status, test_suite.status)
 
 def parse_test_suite(lines: List[str], expected_suite_index: int) -> Optional[TestSuite]:
@@ -282,8 +281,8 @@ def parse_test_plan(lines: List[str]) -> Optional[int]:
 	else:
 		return None
 
-def bubble_up_suite_errors(test_suite_list: List[TestSuite]) -> TestStatus:
-	return bubble_up_errors(lambda x: x.status, test_suite_list)
+def bubble_up_suite_errors(test_suites: Iterable[TestSuite]) -> TestStatus:
+	return bubble_up_errors(x.status for x in test_suites)
 
 def parse_test_result(lines: List[str]) -> TestResult:
 	consume_non_diagnostic(lines)