added test for new parameter

test/test_fail_safe_subprocess.py

 import os
 import unittest
+from subprocess import CalledProcessError
 from time import time
 
 from common_helper_files import get_dir_of_file
@@ -30,6 +31,12 @@ class TestProcessHelperPublic(unittest.TestCase):
         self.assertEqual(output, 'test 123\n', 'result not correct')
         self.assertEqual(rc, 2, 'return code not correct')
 
+    def test_execute_shell_command_with_check(self):
+        with self.assertRaises(CalledProcessError):
+            execute_shell_command("exit 1", check=True)
+        with self.assertRaises(CalledProcessError):
+            execute_shell_command("exit 255", check=True)
+
     def test_execute_shell_command_time_out(self):
         start_time = time()
         output, rc = execute_shell_command_get_return_code('echo \'test 123\' && for i in {1..10}; do sleep 1; done', timeout=1)