fix string quotes (kubeflow#10413)

sdk/python/kfp/cli/diagnose_me/utility_test.py

@@ -25,31 +25,31 @@ class UtilityTest(unittest.TestCase):
     def test_execute_command_oserror(self):
         """Testing stdout and stderr is correctly captured upon OSError."""
         response = utility.ExecutorResponse()
-        err_msg = "Testing handling of OSError"
+        err_msg = 'Testing handling of OSError'
 
-        with patch("subprocess.run") as mock_run:
+        with patch('subprocess.run') as mock_run:
             mock_run.side_effect = MagicMock(side_effect=OSError(err_msg))
             response.execute_command([])
 
-        self.assertEqual(response._stdout, "")
+        self.assertEqual(response._stdout, '')
         self.assertEqual(response._stderr, err_msg)
 
     def test_execute_command_stdout(self):
         """Testing stdout output is correctly captured."""
-        test_string = "test string"
+        test_string = 'test string'
         response = utility.ExecutorResponse()
-        response.execute_command(["echo", test_string])
+        response.execute_command(['echo', test_string])
 
-        self.assertEqual(response._stdout, test_string + "\n")
-        self.assertEqual(response._stderr, "")
+        self.assertEqual(response._stdout, test_string + '\n')
+        self.assertEqual(response._stderr, '')
 
     def test_execute_command_stderr(self):
         """Testing stderr output is correctly captured."""
         response = utility.ExecutorResponse()
-        response.execute_command(["ls", "not_a_real_dir"])
+        response.execute_command(['ls', 'not_a_real_dir'])
 
-        self.assertEqual(response._stdout, "")
-        self.assertIn("No such file", response._stderr)
+        self.assertEqual(response._stdout, '')
+        self.assertIn('No such file', response._stderr)
 
     def test_parse_raw_input_json(self):
         """Testing json stdout is correctly parsed."""