import sys import my_tool def test_no_args(capsys): my_tool.my_cli() captured = capsys.readouterr() assert captured.out.startswith("usage:") def test_version(capsys, monkeypatch): monkeypatch.setattr(sys, "argv", ["", "--version"]) my_tool.my_cli() captured = capsys.readouterr() assert captured.out.startswith("Version:")