public async Task ChallengeFormPostIssuedCorrectly()
        {
            var settings = new TestSettings(
                opt =>
            {
                opt.Authority            = TestServerBuilder.DefaultAuthority;
                opt.AuthenticationMethod = OpenIdConnectRedirectBehavior.FormPost;
                opt.ClientId             = "Test Id";
            });

            var server      = settings.CreateTestServer();
            var transaction = await server.SendAsync(ChallengeEndpoint);

            var res = transaction.Response;

            Assert.Equal(HttpStatusCode.OK, res.StatusCode);
            Assert.Equal("text/html", transaction.Response.Content.Headers.ContentType.MediaType);

            var body = await res.Content.ReadAsStringAsync();

            settings.ValidateChallengeFormPost(
                body,
                OpenIdConnectParameterNames.ClientId,
                OpenIdConnectParameterNames.ResponseType,
                OpenIdConnectParameterNames.ResponseMode,
                OpenIdConnectParameterNames.Scope,
                OpenIdConnectParameterNames.RedirectUri);
        }