public void OAuth_PostOAuthRefresh()
        {
            // ARRANGE
            string          clientId = "GS36SG653FDAY", clientSecret = "H7BD5D6G56", grand = "pw", refreshToken = "things";
            IRequestBuilder builder  = new DracoonRequestBuilder(FactoryClients.OAuthMock);
            RestRequest     expected = FactoryRestSharp.RestRequestWithoutAuth(OAuthConfig.OAuthPostRefreshToken, Method.POST);

            expected.AddHeader("Authorization", "Basic " + Convert.ToBase64String(Encoding.UTF8.GetBytes(clientId + ":" + clientSecret)));
            expected.AddParameter("grant_type", grand, ParameterType.GetOrPost);
            expected.AddParameter("refresh_token", refreshToken, ParameterType.GetOrPost);

            // ACT
            IRestRequest actual = builder.PostOAuthRefresh(clientId, clientSecret, grand, refreshToken);

            // ASSERT
            Assert.Equal(expected, actual, new RestRequestComparer());
        }