test(utils): add test for get_backup_file_path when git.find_project_root returns None

Author: crai0

tests/test_cz_utils.py

@@ -1,4 +1,5 @@
 import pytest
+from pytest_mock import MockFixture
 
 from commitizen.cz import exceptions, utils
 
@@ -17,3 +18,9 @@ def test_multiple_line_breaker():
 
     result = utils.multiple_line_breaker(message, "is")
     assert result == "th\n\nthe first line    | and th\n\nthe second line"
+
+
+def test_get_backup_file_path_no_project_root(mocker: MockFixture):
+    project_root_mock = mocker.patch("commitizen.git.find_git_project_root")
+    project_root_mock.return_value = None
+    assert utils.get_backup_file_path()