public async Task JsonErrorResult()
        {
            AvaTaxError avataxError = null;

            try
            {
                var result = await _client.ChangePasswordAsync(new PasswordChangeModel
                {
                }).ConfigureAwait(false);
            }
            catch (AvaTaxError e)
            {
                avataxError = e;
            }

            Assert.NotNull(avataxError);
            Assert.True(avataxError.error.error.message.Contains("Field oldPassword is required"));
        }
        public async Task NonJsonErrorResult()
        {
            AvaTaxError avataxError = null;

            try
            {
                // make a client that points to a server that will give a 404 for ping
                var client = new AvaTaxClient(GetType().Name,
                                              GetType().GetTypeInfo().Assembly.ImageRuntimeVersion.ToString(),
                                              Environment.MachineName, new Uri("https://www.google.com"));

                var result = await client.PingAsync().ConfigureAwait(false);
            }
            catch (AvaTaxError e)
            {
                avataxError = e;
            }

            Assert.NotNull(avataxError);
            Assert.True(avataxError.error.error.message.Contains("the response is in an unexpected format"));
            Assert.True(avataxError.error.error.details[0].description.ToLower().Contains("not found"));
        }