kunit: tool: readability tweaks in KernelCI json generation logic

Use a more idiomatic check that a list is non-empty (`if mylist:`) and
simplify the function body by dedenting and using a dict to map between
the kunit TestStatus enum => KernelCI json status string.

The dict hopefully makes it less likely to have bugs like commit
9a6bb30a ("kunit: tool: fix --json output for skipped tests").
Signed-off-by: Daniel Latypov <dlatypov@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit_json.py

@@ -16,24 +16,24 @@ from typing import Any, Dict
 
 JsonObj = Dict[str, Any]
 
+_status_map: Dict[TestStatus, str] = {
+	TestStatus.SUCCESS: "PASS",
+	TestStatus.SKIPPED: "SKIP",
+	TestStatus.TEST_CRASHED: "ERROR",
+}
+
 def _get_group_json(test: Test, def_config: str, build_dir: str) -> JsonObj:
 	sub_groups = []  # List[JsonObj]
 	test_cases = []  # List[JsonObj]
 
 	for subtest in test.subtests:
-		if len(subtest.subtests):
+		if subtest.subtests:
 			sub_group = _get_group_json(subtest, def_config,
 				build_dir)
 			sub_groups.append(sub_group)
-		else:
-			test_case = {"name": subtest.name, "status": "FAIL"}
-			if subtest.status == TestStatus.SUCCESS:
-				test_case["status"] = "PASS"
-			elif subtest.status == TestStatus.SKIPPED:
-				test_case["status"] = "SKIP"
-			elif subtest.status == TestStatus.TEST_CRASHED:
-				test_case["status"] = "ERROR"
-			test_cases.append(test_case)
+			continue
+		status = _status_map.get(subtest.status, "FAIL")
+		test_cases.append({"name": subtest.name, "status": status})
 
 	test_group = {
 		"name": test.name,