def METHOD_NAME(self):
    ctx = utils.FormattedDict({
        'BUILD_DIR': self.build_dir,
        'PHP_VERSION': '8.1.13',
        'SOME_JUNK': 'jkl;'
    })
    class MyExtn(PHPExtensionHelper):
        def _defaults(self):
            return {
                'DEFAULT_JUNK': 'asdf',
                'SOME_JUNK': 'qwerty'
            }
    ext = MyExtn(ctx)
    eq_(4, len(ext._ctx))
    eq_('asdf', ext._ctx['DEFAULT_JUNK'])
    eq_('jkl;', ext._ctx['SOME_JUNK'])
    eq_('8.1.13', ext._ctx['PHP_VERSION'])