LoginPageGeneratingWebFilter conditionally renders formLogin

Issue: gh-4807

config/src/test/java/org/springframework/security/config/web/server/FormLoginTests.java

@@ -17,6 +17,8 @@
 package org.springframework.security.config.web.server;
 
 import org.junit.Test;
+import org.openqa.selenium.By;
+import org.openqa.selenium.NoSuchElementException;
 import org.openqa.selenium.WebDriver;
 import org.openqa.selenium.WebElement;
 import org.openqa.selenium.support.FindBy;
@@ -36,6 +38,8 @@ import org.springframework.web.server.ServerWebExchange;
 import reactor.core.publisher.Mono;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 /**
  * @author Rob Winch
@@ -204,9 +208,10 @@ public class FormLoginTests {
 
 		private LoginForm loginForm;
 
+		private OAuth2Login oauth2Login = new OAuth2Login();
+
 		public DefaultLoginPage(WebDriver webDriver) {
 			this.driver = webDriver;
-			this.loginForm = PageFactory.initElements(webDriver, LoginForm.class);
 		}
 
 		static DefaultLoginPage create(WebDriver driver) {
@@ -228,10 +233,23 @@ public class FormLoginTests {
 			return this;
 		}
 
+		public DefaultLoginPage assertLoginFormNotPresent() {
+			assertThatThrownBy(() -> loginForm().username(""))
+					.isInstanceOf(NoSuchElementException.class);
+			return this;
+		}
+
 		public LoginForm loginForm() {
+			if (this.loginForm == null) {
+				this.loginForm = PageFactory.initElements(this.driver, LoginForm.class);
+			}
 			return this.loginForm;
 		}
 
+		public OAuth2Login oauth2Login() {
+			return this.oauth2Login;
+		}
+
 		static DefaultLoginPage to(WebDriver driver) {
 			driver.get("http://localhost/login");
 			return PageFactory.initElements(driver, DefaultLoginPage.class);
@@ -263,6 +281,22 @@ public class FormLoginTests {
 				return PageFactory.initElements(this.driver, page);
 			}
 		}
+
+		public class OAuth2Login {
+			public WebElement findClientRegistrationByName(String clientName) {
+				return DefaultLoginPage.this.driver.findElement(By.linkText(clientName));
+			}
+
+			public OAuth2Login assertClientRegistrationByName(String clientName) {
+				assertThatCode(() -> findClientRegistrationByName(clientName))
+						.doesNotThrowAnyException();
+				return this;
+			}
+
+			public DefaultLoginPage and() {
+				return DefaultLoginPage.this;
+			}
+		}
 	}
 
 	public static class DefaultLogoutPage {

config/src/test/java/org/springframework/security/config/web/server/OAuth2LoginTests.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2002-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.config.web.server;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.openqa.selenium.WebDriver;
+import org.openqa.selenium.WebElement;
+import org.openqa.selenium.support.FindBy;
+import org.openqa.selenium.support.PageFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
+import org.springframework.security.config.annotation.web.reactive.ServerHttpSecurityConfigurationBuilder;
+import org.springframework.security.config.oauth2.client.CommonOAuth2Provider;
+import org.springframework.security.config.test.SpringTestRule;
+import org.springframework.security.htmlunit.server.WebTestClientHtmlUnitDriverBuilder;
+import org.springframework.security.oauth2.client.registration.ClientRegistration;
+import org.springframework.security.oauth2.client.registration.InMemoryReactiveClientRegistrationRepository;
+import org.springframework.security.oauth2.client.registration.ReactiveClientRegistrationRepository;
+import org.springframework.security.test.web.reactive.server.WebTestClientBuilder;
+import org.springframework.security.web.server.SecurityWebFilterChain;
+import org.springframework.security.web.server.WebFilterChainProxy;
+import org.springframework.security.web.server.authentication.RedirectServerAuthenticationSuccessHandler;
+import org.springframework.security.web.server.csrf.CsrfToken;
+import org.springframework.stereotype.Controller;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.server.ServerWebExchange;
+
+import reactor.core.publisher.Mono;
+
+/**
+ * @author Rob Winch
+ * @since 5.1
+ */
+public class OAuth2LoginTests {
+
+	@Rule
+	public final SpringTestRule spring = new SpringTestRule();
+
+	@Autowired
+	private WebFilterChainProxy springSecurity;
+
+	private ClientRegistration github = CommonOAuth2Provider.GITHUB
+			.getBuilder("github")
+			.clientId("client")
+			.clientSecret("secret")
+			.build();
+
+	@Test
+	public void defaultLoginPageWithMultipleClientRegistrationsThenLinks() {
+		this.spring.register(OAuth2LoginWithMulitpleClientRegistrations.class).autowire();
+
+		WebTestClient webTestClient = WebTestClientBuilder
+				.bindToWebFilters(this.springSecurity)
+				.build();
+
+		WebDriver driver = WebTestClientHtmlUnitDriverBuilder
+				.webTestClientSetup(webTestClient)
+				.build();
+
+		FormLoginTests.DefaultLoginPage loginPage = FormLoginTests.HomePage
+				.to(driver, FormLoginTests.DefaultLoginPage.class)
+				.assertAt()
+				.assertLoginFormNotPresent()
+				.oauth2Login()
+					.assertClientRegistrationByName(this.github.getClientName())
+					.and();
+	}
+
+	@EnableWebFluxSecurity
+	static class OAuth2LoginWithMulitpleClientRegistrations {
+		@Bean
+		InMemoryReactiveClientRegistrationRepository clientRegistrationRepository() {
+			ClientRegistration github = CommonOAuth2Provider.GITHUB
+					.getBuilder("github")
+					.clientId("client")
+					.clientSecret("secret")
+					.build();
+			ClientRegistration google = CommonOAuth2Provider.GOOGLE
+					.getBuilder("google")
+					.clientId("client")
+					.clientSecret("secret")
+					.build();
+			return new InMemoryReactiveClientRegistrationRepository(github, google);
+		}
+	}
+}