def test_config_cmdline_options_only_lowercase(): 

       o = py.test.ensuretemp('test_config_cmdline_options_only_lowercase')

       o.ensure("conftest.py").write(py.code.Source(""" 

           import py

           Option = py.test.config.Option

           options = py.test.config.addoptions("testing group", 

               Option('-g', '--glong', action="store", default=42,

                      type="int", dest="gdest", help="g value."), 

               )

           """))

->     old = o.chdir() 

       try: 

           py.test.raises(ValueError, """

               py.test.config._reparse(['-g', '17'])

           """)

       finally: 

           old.chdir()