public void GivenDefaultSettingsRequested_RedirectToAuthenticate_ReturnsAUri()
            {
                // Arrange.
                var facebookProvider = new FacebookProvider("aa", "bb", new Uri("http://www.2p1s.com"));
                var facebookAuthenticationServiceSettings = new FacebookAuthenticationServiceSettings();

                // Act.
                var result = facebookProvider.RedirectToAuthenticate(facebookAuthenticationServiceSettings);

                // Assert.
                Assert.NotNull(result);
                Assert.Equal("https://www.facebook.com/dialog/oauth?client_id=aa&scope=email&redirect_uri=http://www.2p1s.com/", result.AbsoluteUri);
            }
            public void GivenMobileAndDisplayAreRequested_RedirectToAuthenticate_ReturnsAUri()
            {
                // Arrange.
                var facebookProvider = new FacebookProvider("aa", "bb", new Uri("http://www.2p1s.com"));
                var facebookAuthenticationServiceSettings = new FacebookAuthenticationServiceSettings
                                                            {
                                                                IsMobile = true,
                                                                Display = DisplayType.Touch
                                                            };
                // Act.
                var result = facebookProvider.RedirectToAuthenticate(facebookAuthenticationServiceSettings);

                // Assert.
                Assert.NotNull(result);
                Assert.Equal("https://m.facebook.com/dialog/oauth?client_id=aa&scope=email&display=touch&redirect_uri=http://www.2p1s.com/", result.AbsoluteUri);
            }