Improve Spring Session sample

This commit improves the Spring Session sample by providing multiple
build profiles that make it possible to easily try out different session
stores. By default, JDBC session store backed by an in-memory embedded H2
database is used.

See gh-10351

spring-boot-samples/spring-boot-sample-session/src/test/java/sample/session/SampleSessionApplicationTests.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2012-2017 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 sample.session.redis;
+
+import java.net.URI;
+
+import org.junit.Test;
+
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.client.RestTemplate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SampleSessionApplication}.
+ *
+ * @author Andy Wilkinson
+ */
+public class SampleSessionApplicationTests {
+
+	@Test
+	public void sessionExpiry() throws Exception {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder()
+				.sources(SampleSessionApplication.class)
+				.properties("server.port:0")
+				.initializers(new ServerPortInfoApplicationContextInitializer())
+				.run();
+		String port = context.getEnvironment().getProperty("local.server.port");
+
+		URI uri = URI.create("http://localhost:" + port + "/");
+		RestTemplate restTemplate = new RestTemplate();
+
+		ResponseEntity<String> response = restTemplate.getForEntity(uri, String.class);
+		String uuid1 = response.getBody();
+		HttpHeaders requestHeaders = new HttpHeaders();
+		requestHeaders.set("Cookie", response.getHeaders().getFirst("Set-Cookie"));
+
+		RequestEntity<Void> request = new RequestEntity<>(requestHeaders, HttpMethod.GET,
+				uri);
+
+		String uuid2 = restTemplate.exchange(request, String.class).getBody();
+		assertThat(uuid1).isEqualTo(uuid2);
+
+		Thread.sleep(5000);
+
+		String uuid3 = restTemplate.exchange(request, String.class).getBody();
+		assertThat(uuid2).isNotEqualTo(uuid3);
+	}
+
+}