Configure SessionCookieConfig in MockServletWebServer

Closes gh-26479

spring-boot-project/spring-boot-tools/spring-boot-test-support/build.gradle

@@ -30,9 +30,12 @@ dependencies {
 	implementation("org.hamcrest:hamcrest-core")
 	implementation("org.hamcrest:hamcrest-library")
 	implementation("org.springframework:spring-core")
+	implementation("org.springframework:spring-test")
 
+	testImplementation("javax.servlet:javax.servlet-api")
 	testImplementation("org.junit.jupiter:junit-jupiter")
 	testImplementation("org.springframework:spring-context")
 
 	testRuntimeOnly("org.hibernate.validator:hibernate-validator")
+	testRuntimeOnly("org.mockito:mockito-core")
 }

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/web/servlet/MockServletWebServer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2021 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.
@@ -30,6 +30,9 @@ import javax.servlet.Servlet;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
+import javax.servlet.SessionCookieConfig;
+
+import org.springframework.mock.web.MockSessionCookieConfig;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
@@ -76,6 +79,8 @@ public abstract class MockServletWebServer {
 				MockServletWebServer.this.registeredFilters.add(registeredFilter);
 				return registeredFilter.getRegistration();
 			});
+			final SessionCookieConfig sessionCookieConfig = new MockSessionCookieConfig();
+			given(this.servletContext.getSessionCookieConfig()).willReturn(sessionCookieConfig);
 			final Map<String, String> initParameters = new HashMap<>();
 			given(this.servletContext.setInitParameter(anyString(), anyString())).will((invocation) -> {
 				initParameters.put(invocation.getArgument(0), invocation.getArgument(1));

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/test/java/org/springframework/boot/testsupport/web/servlet/MockServletWebServerTests.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2012-2021 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
+ *
+ *      https://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.boot.testsupport.web.servlet;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.mock.web.MockSessionCookieConfig;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link MockServletWebServer}.
+ *
+ * @author Stephane Nicoll
+ */
+class MockServletWebServerTests {
+
+	@Test
+	void servletContextIsConfigured() {
+		MockServletWebServer server = TestMockServletWebServer.create();
+		assertThat(server.getServletContext()).isNotNull();
+	}
+
+	@Test
+	void servletContextHasSessionCookieConfigConfigured() {
+		MockServletWebServer server = TestMockServletWebServer.create();
+		assertThat(server.getServletContext().getSessionCookieConfig()).isNotNull()
+				.isInstanceOf(MockSessionCookieConfig.class);
+	}
+
+	private static final class TestMockServletWebServer extends MockServletWebServer {
+
+		private TestMockServletWebServer(Initializer[] initializers, int port) {
+			super(initializers, port);
+		}
+
+		static MockServletWebServer create(Initializer... initializers) {
+			return new TestMockServletWebServer(initializers, 8080);
+		}
+
+	}
+
+}