public async Task OAuth2Client_GetAuthorizationCodeAsync()
        {
            const string expectedAuthCode = "68c39cbd8d";

            var baseUri = new Uri("https://example.com");
            OAuth2ServerEndpoints endpoints = CreateEndpoints(baseUri);

            var httpHandler = new TestHttpMessageHandler {
                ThrowOnUnexpectedRequest = true
            };

            string[] expectedScopes = { "read", "write", "delete" };

            OAuth2Application app = CreateTestApplication();

            var server = new TestOAuth2Server(endpoints);

            server.RegisterApplication(app);
            server.Bind(httpHandler);
            server.TokenGenerator.AuthCodes.Add(expectedAuthCode);

            IOAuth2WebBrowser browser = new TestOAuth2WebBrowser(httpHandler);

            OAuth2Client client = CreateClient(httpHandler, endpoints);

            OAuth2AuthorizationCodeResult result = await client.GetAuthorizationCodeAsync(expectedScopes, browser, CancellationToken.None);

            Assert.Equal(expectedAuthCode, result.Code);
        }
        public async Task OAuth2Client_E2E_InteractiveWebFlowAndRefresh()
        {
            const string expectedAuthCode      = "e78a711d11";
            const string expectedAccessToken1  = "LET_ME_IN-1";
            const string expectedAccessToken2  = "LET_ME_IN-2";
            const string expectedRefreshToken1 = "REFRESH_ME-1";
            const string expectedRefreshToken2 = "REFRESH_ME-2";

            var baseUri = new Uri("https://example.com");
            OAuth2ServerEndpoints endpoints = CreateEndpoints(baseUri);

            var httpHandler = new TestHttpMessageHandler {
                ThrowOnUnexpectedRequest = true
            };

            string[] expectedScopes = { "read", "write", "delete" };

            OAuth2Application app = CreateTestApplication();

            var server = new TestOAuth2Server(endpoints);

            server.RegisterApplication(app);
            server.Bind(httpHandler);
            server.TokenGenerator.AuthCodes.Add(expectedAuthCode);
            server.TokenGenerator.AccessTokens.Add(expectedAccessToken1);
            server.TokenGenerator.RefreshTokens.Add(expectedRefreshToken1);

            IOAuth2WebBrowser browser = new TestOAuth2WebBrowser(httpHandler);

            OAuth2Client client = CreateClient(httpHandler, endpoints);

            OAuth2AuthorizationCodeResult authCodeResult = await client.GetAuthorizationCodeAsync(
                expectedScopes, browser, CancellationToken.None);

            OAuth2TokenResult result1 = await client.GetTokenByAuthorizationCodeAsync(authCodeResult, CancellationToken.None);

            Assert.NotNull(result1);
            Assert.Equal(expectedScopes, result1.Scopes);
            Assert.Equal(expectedAccessToken1, result1.AccessToken);
            Assert.Equal(expectedRefreshToken1, result1.RefreshToken);

            server.TokenGenerator.AccessTokens.Add(expectedAccessToken2);
            server.TokenGenerator.RefreshTokens.Add(expectedRefreshToken2);

            OAuth2TokenResult result2 = await client.GetTokenByRefreshTokenAsync(result1.RefreshToken, CancellationToken.None);

            Assert.NotNull(result2);
            Assert.Equal(expectedScopes, result2.Scopes);
            Assert.Equal(expectedAccessToken2, result2.AccessToken);
            Assert.Equal(expectedRefreshToken2, result2.RefreshToken);
        }