[PATCH v2] kunit: tool: fix _list_tests filtering wrong variable when list has TAP prefix

[Mohammad abukhader <mohammad.abukhader@hotmail.com>]

From: Mohammad Abu-Khader <mohammad.abukhader@hotmail.com>

`_list_tests()` runs the kernel to list tests, strips printk timestamp
lines via `extract_tap_lines()`, then drops the dummy TAP header from
the cleaned `lines`.  However the subsequent regex filter mistakenly
operates on the original `output` instead of the cleaned `lines`.  When
the kernel output includes timestamp prefixes (common with UML or slower
setups), e.g.:

  [    0.100000] suite.test1
  [    0.100000] suite.test2

the anchored regex `^[^\s.]+\.[^\s.]+$` rejects them and `--list_tests`
returns an empty list.

Filter `lines` instead of `output`, matching the behavior of the
adjacent `_list_tests_attr()` which already returns the cleaned list.

Add a regression test with timestamp-prefixed input to verify the fix.

Fixes: 723c8258c8fe ("kunit: tool: Add command line interface to filter and report attributes")
Signed-off-by: Mohammad Abu-Khader <mohammad.abukhader@hotmail.com>
---
 tools/testing/kunit/kunit.py           |  2 +-
 tools/testing/kunit/kunit_tool_test.py | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/tools/testing/kunit/kunit.py b/tools/testing/kunit/kunit.py
index ac3f7159e67f..91d234ac3b57 100755
--- a/tools/testing/kunit/kunit.py
+++ b/tools/testing/kunit/kunit.py
@@ -126,7 +126,7 @@ def _list_tests(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest)
 	lines.pop()
 
 	# Filter out any extraneous non-test output that might have gotten mixed in.
-	return [l for l in output if re.match(r'^[^\s.]+\.[^\s.]+$', l)]
+	return [l for l in lines if re.match(r'^[^\s.]+\.[^\s.]+$', l)]
 
 def _list_tests_attr(linux: kunit_kernel.LinuxSourceTree, request: KunitExecRequest) -> Iterable[str]:
 	args = ['kunit.action=list_attr']
diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py
index da88c3a1651d..85ae21754bdf 100755
--- a/tools/testing/kunit/kunit_tool_test.py
+++ b/tools/testing/kunit/kunit_tool_test.py
@@ -979,6 +979,18 @@ class KUnitMainTest(unittest.TestCase):
 		self.linux_source_mock.run_kernel.assert_called_once_with(
 			args=['kunit.action=list'], build_dir='.kunit', filter_glob='suite*', filter='', filter_action=None, timeout=300)
 
+	def test_list_tests_with_prefix(self):
+		want = ['suite.test1', 'suite.test2', 'suite2.test1']
+		self.linux_source_mock.run_kernel.return_value = [
+			'[    0.100000] TAP version 14',
+			'[    0.200000] suite.test1',
+			'[    0.200000] suite.test2',
+			'[    0.300000] suite2.test1']
+
+		got = kunit._list_tests(self.linux_source_mock,
+				     kunit.KunitExecRequest(None, None, None, False, False, '.kunit', 300, 'suite*', '', None, None, 'suite', False, False, False))
+		self.assertEqual(got, want)
+
 	@mock.patch.object(kunit, '_list_tests')
 	def test_run_isolated_by_suite(self, mock_tests):
 		mock_tests.return_value = ['suite.test1', 'suite.test2', 'suite2.test1']
-- 
2.55.0