kunit: tool: fix unit test cleanup handling

* Stop leaking file objects.
* Use self.addCleanup() to ensure we call cleanup functions even if
setUp() fails.
* use mock.patch.stopall instead of more error-prone manual approach

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

Author: dlatypov

tools/testing/kunit/kunit_tool_test.py

@@ -288,19 +288,17 @@ def __eq__(self, other):
 class KUnitMainTest(unittest.TestCase):
 	def setUp(self):
 		path = get_absolute_path('test_data/test_is_test_passed-all_passed.log')
-		file = open(path)
-		all_passed_log = file.readlines()
-		self.print_patch = mock.patch('builtins.print')
-		self.print_mock = self.print_patch.start()
+		with open(path) as file:
+			all_passed_log = file.readlines()
+
+		self.print_mock = mock.patch('builtins.print').start()
+		self.addCleanup(mock.patch.stopall)
+
 		self.linux_source_mock = mock.Mock()
 		self.linux_source_mock.build_reconfig = mock.Mock(return_value=True)
 		self.linux_source_mock.build_um_kernel = mock.Mock(return_value=True)
 		self.linux_source_mock.run_kernel = mock.Mock(return_value=all_passed_log)
 
-	def tearDown(self):
-		self.print_patch.stop()
-		pass
-
 	def test_config_passes_args_pass(self):
 		kunit.main(['config', '--build_dir=.kunit'], self.linux_source_mock)
 		assert self.linux_source_mock.build_reconfig.call_count == 1