Add HttpStatusReturningServerLogoutSuccessHandler

An HttpStatusReturningServerLogoutSuccessHandler is missing on the
reactive side - essentially the reactive equivalent of
HttpStatusReturningLogoutSuccessHandler.

Fixes gh-5081

web/src/test/java/org/springframework/security/web/server/authentication/logout/HttpStatusReturningServerLogoutSuccessHandlerTests.java

@@ -0,0 +1,67 @@
+/*
+ * 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.web.server.authentication.logout;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.Mockito.mock;
+
+import org.junit.Test;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.web.server.MockServerWebExchange;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.web.server.WebFilterExchange;
+import org.springframework.web.server.WebFilterChain;
+
+/**
+ * @author Eric Deandrea
+ * @since 5.1
+ */
+public class HttpStatusReturningServerLogoutSuccessHandlerTests {
+	@Test
+	public void defaultHttpStatusBeingReturned() {
+		WebFilterExchange filterExchange = buildFilterExchange();
+		new HttpStatusReturningServerLogoutSuccessHandler()
+				.onLogoutSuccess(filterExchange, mock(Authentication.class)).block();
+
+		assertThat(filterExchange.getExchange().getResponse().getStatusCode()).isEqualTo(HttpStatus.OK);
+	}
+
+	@Test
+	public void customHttpStatusBeingReturned() {
+		WebFilterExchange filterExchange = buildFilterExchange();
+		new HttpStatusReturningServerLogoutSuccessHandler(HttpStatus.NO_CONTENT)
+				.onLogoutSuccess(filterExchange, mock(Authentication.class)).block();
+
+		assertThat(filterExchange.getExchange().getResponse().getStatusCode()).isEqualTo(HttpStatus.NO_CONTENT);
+	}
+
+	@Test
+	public void nullHttpStatusThrowsException() {
+		assertThatExceptionOfType(IllegalArgumentException.class)
+				.isThrownBy(() -> new HttpStatusReturningServerLogoutSuccessHandler(null))
+				.withMessage("The provided HttpStatus must not be null.");
+	}
+
+	private static WebFilterExchange buildFilterExchange() {
+		MockServerHttpRequest request = MockServerHttpRequest.get("/").build();
+		MockServerWebExchange exchange = MockServerWebExchange.from(request);
+
+		return new WebFilterExchange(exchange, mock(WebFilterChain.class));
+	}
+}