Add support for server-side events and tests

User can POST to web endpoint in SSE style, i.e:

HTTP/1.1
Content-Type: text/event-stream

data:foo

data:bar

Will be converted to a Flux with values foo and bar

spring-cloud-function-web/src/test/java/org/springframework/cloud/function/web/RestApplicationTests.java

@@ -0,0 +1,102 @@
+/*
+ * Copyright 2016-2017 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 org.springframework.cloud.function.web;
+
+import java.net.URI;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.context.embedded.LocalServerPort;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.context.annotation.Bean;
+import org.springframework.http.MediaType;
+import org.springframework.http.RequestEntity;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.util.StringUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import reactor.core.publisher.Flux;
+
+/**
+ * @author Dave Syer
+ *
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
+public class RestApplicationTests {
+
+	@LocalServerPort
+	private int port;
+	private TestRestTemplate rest = new TestRestTemplate();
+
+	@Test
+	public void wordsSSE() throws Exception {
+		assertThat(
+				rest.exchange(
+						RequestEntity.get(new URI("http://localhost:" + port + "/words"))
+								.accept(MediaType.TEXT_EVENT_STREAM).build(),
+						String.class).getBody()).isEqualTo(sse("foo", "bar"));
+	}
+
+	@Test
+	public void words() throws Exception {
+		assertThat(rest.exchange(
+				RequestEntity.get(new URI("http://localhost:" + port + "/words")).build(),
+				String.class).getBody()).isEqualTo("foobar");
+	}
+
+	@Test
+	public void uppercase() {
+		assertThat(rest.postForObject("http://localhost:" + port + "/uppercase",
+				"foo\nbar", String.class)).isEqualTo("[FOO][BAR]");
+	}
+
+	@Test
+	public void uppercaseSSE() throws Exception {
+		assertThat(rest.exchange(
+				RequestEntity.post(new URI("http://localhost:" + port + "/uppercase"))
+						.accept(MediaType.TEXT_EVENT_STREAM)
+						.contentType(MediaType.TEXT_EVENT_STREAM).body(sse("foo", "bar")),
+				String.class).getBody()).isEqualTo(sse("[FOO]", "[BAR]"));
+	}
+
+	private String sse(String... values) {
+		return "data:" + StringUtils.arrayToDelimitedString(values, "\n\ndata:") + "\n\n";
+	}
+
+	@SpringBootApplication
+	public static class TestConfiguration {
+
+		@Bean
+		public Function<Flux<String>, Flux<String>> uppercase() {
+			return flux -> flux.map(value -> "[" + value.trim().toUpperCase() + "]");
+		}
+
+		@Bean
+		public Supplier<Flux<String>> words() {
+			return () -> Flux.fromArray(new String[] { "foo", "bar" });
+		}
+
+	}
+
+}