How to use the webtest.utils.encode_params function in WebTest

def test_encode_params_None(self):
        self.assertEqual(utils.encode_params(None, None), None)

inline_uploads = []

        # this supports OrderedDict
        if isinstance(params, dict) or hasattr(params, 'items'):
            params = list(params.items())

        if isinstance(params, (list, tuple)):
            inline_uploads = [v for (k, v) in params
                              if isinstance(v, (forms.File, forms.Upload))]

        if len(inline_uploads) > 0:
            content_type, params = self.encode_multipart(
                params, upload_files or ())
            environ['CONTENT_TYPE'] = content_type
        else:
            params = utils.encode_params(params, content_type)
            if upload_files or \
                (content_type and
                 to_bytes(content_type).startswith(b'multipart')):
                params = urlparse.parse_qsl(params, keep_blank_values=True)
                content_type, params = self.encode_multipart(
                    params, upload_files or ())
                environ['CONTENT_TYPE'] = content_type
            elif params:
                environ.setdefault('CONTENT_TYPE',
                                   str('application/x-www-form-urlencoded'))

        if content_type is not None:
            environ['CONTENT_TYPE'] = content_type
        environ['REQUEST_METHOD'] = str(method)
        url = str(url)
        url = self._remove_fragment(url)

def test_encode_params_NoDefault(self):
        self.assertEqual(utils.encode_params(utils.NoDefault, None), '')

def test_encode_params_no_charset(self):
        # no content_type at all
        self.assertEqual(utils.encode_params({'foo': 'bar'}, None), 'foo=bar')
        # content_type without "charset=xxxx"
        self.assertEqual(utils.encode_params({'foo': 'bar'}, 'ba'), 'foo=bar')

def test_encode_params_charset_utf8(self):
        # charset is using inconsistent casing on purpose, it should still work
        self.assertEqual(utils.encode_params({'f': '€'}, ' CHARset=uTF-8; '),
                          'f=%E2%82%AC')