test(changelog): ensure error on missing changelog template filename

Author: ongdisheng

tests/commands/test_changelog_command.py

@@ -1914,6 +1914,32 @@ def test_export_changelog_template_from_plugin(
 asserttarget.read_text() ==tpl
 
 
+deftest_export_changelog_template_fails_when_template_has_no_filename(
+mocker: MockFixture,
+tmp_commitizen_project: Path,
+):
+project_root=Path(tmp_commitizen_project)
+target=project_root/"changelog.jinja"
+
+# Mock a template object with no filename
+classFakeTemplate:
+filename=None
+
+# Patch get_changelog_template to return a template without a filename
+mocker.patch(
+"commitizen.changelog.get_changelog_template", return_value=FakeTemplate()
+ )
+
+args= ["cz", "changelog", "--export-template", str(target)]
+mocker.patch.object(sys, "argv", args)
+
+withpytest.raises(NotAllowed) asexc_info:
+cli.main()
+
+assertnottarget.exists()
+assert"Template filename is not set"instr(exc_info.value)
+
+
 @skip_below_py_3_13
 deftest_changelog_command_shows_description_when_use_help_option(
 mocker: MockFixture, capsys, file_regression