Add ServerSentEventHttpMessageReader

This HTTP message reader parse incoming Server-Sent
Events and turn them into Flux<String>, Flux<Pojo>
or Flux<ServerSentEvent>.

Issue: SPR-14539

spring-web/src/test/java/org/springframework/http/codec/ServerSentEventHttpMessageReaderTests.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright 2002-2016 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.http.codec;
+
+import java.time.Duration;
+import java.util.Collections;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+import reactor.core.publisher.Flux;
+import reactor.test.StepVerifier;
+
+import org.springframework.core.ResolvableType;
+import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
+import org.springframework.http.MediaType;
+import org.springframework.http.codec.json.Jackson2JsonDecoder;
+import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
+
+/**
+ * @author Sebastien Deleuze
+ */
+public class ServerSentEventHttpMessageReaderTests extends AbstractDataBufferAllocatingTestCase {
+
+	private ServerSentEventHttpMessageReader messageReader = new ServerSentEventHttpMessageReader(
+			Collections.singletonList(new Jackson2JsonDecoder()));
+
+	@Test
+	public void cantRead() {
+		assertFalse(messageReader.canRead(ResolvableType.forClass(Object.class),
+				new MediaType("foo", "bar")));
+		assertFalse(messageReader.canRead(ResolvableType.forClass(Object.class), null));
+	}
+
+	@Test
+	public void canRead() {
+		assertTrue(messageReader.canRead(ResolvableType.forClass(Object.class),
+				new MediaType("text", "event-stream")));
+		assertTrue(messageReader.canRead(ResolvableType.forClass(ServerSentEvent.class),
+				new MediaType("foo", "bar")));
+	}
+
+	@Test
+	public void readServerSentEvents() {
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.setBody("id:c42\nevent:foo\nretry:123\n:bla\n:bla bla\n:bla bla bla\ndata:bar\n\n" +
+			 	"id:c43\nevent:bar\nretry:456\ndata:baz\n\n");
+		Flux<ServerSentEvent> events = messageReader
+				.read(ResolvableType.forClassWithGenerics(ServerSentEvent.class, String.class),
+						request, Collections.emptyMap()).cast(ServerSentEvent.class);
+
+		StepVerifier.create(events)
+				.consumeNextWith(event -> {
+					assertEquals("c42", event.id().get());
+					assertEquals("foo", event.event().get());
+					assertEquals(Duration.ofMillis(123), event.retry().get());
+					assertEquals("bla\nbla bla\nbla bla bla", event.comment().get());
+					assertEquals("bar", event.data().get());
+				})
+				.consumeNextWith(event -> {
+					assertEquals("c43", event.id().get());
+					assertEquals("bar", event.event().get());
+					assertEquals(Duration.ofMillis(456), event.retry().get());
+					assertFalse(event.comment().isPresent());
+					assertEquals("baz", event.data().get());
+				})
+				.expectComplete()
+				.verify();
+	}
+
+	@Test
+	public void readServerSentEventsWithMultipleChunks() {
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.setBody(Flux.just(stringBuffer("id:c42\nev"), stringBuffer("ent:foo\nretry:123\n:bla\n:bla bla\n:bla bla bla\ndata:"),
+				stringBuffer("bar\n\nid:c43\nevent:bar\nretry:456\ndata:baz\n\n")));
+		Flux<ServerSentEvent> events = messageReader
+				.read(ResolvableType.forClassWithGenerics(ServerSentEvent.class, String.class),
+						request, Collections.emptyMap()).cast(ServerSentEvent.class);
+
+		StepVerifier.create(events)
+				.consumeNextWith(event -> {
+					assertEquals("c42", event.id().get());
+					assertEquals("foo", event.event().get());
+					assertEquals(Duration.ofMillis(123), event.retry().get());
+					assertEquals("bla\nbla bla\nbla bla bla", event.comment().get());
+					assertEquals("bar", event.data().get());
+				})
+				.consumeNextWith(event -> {
+					assertEquals("c43", event.id().get());
+					assertEquals("bar", event.event().get());
+					assertEquals(Duration.ofMillis(456), event.retry().get());
+					assertFalse(event.comment().isPresent());
+					assertEquals("baz", event.data().get());
+				})
+				.expectComplete()
+				.verify();
+	}
+
+	@Test
+	public void readString() {
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.setBody("data:foo\ndata:bar\n\ndata:baz\n\n");
+		Flux<String> data = messageReader.read(ResolvableType.forClass(String.class),
+				request, Collections.emptyMap()).cast(String.class);
+
+		StepVerifier.create(data)
+				.expectNextMatches(elem -> elem.equals("foo\nbar"))
+				.expectNextMatches(elem -> elem.equals("baz"))
+				.expectComplete()
+				.verify();
+	}
+
+	@Test
+	public void readPojo() {
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.setBody("data:{\"foo\": \"foofoo\", \"bar\": \"barbar\"}\n\n" +
+		"data:{\"foo\": \"foofoofoo\", \"bar\": \"barbarbar\"}\n\n");
+		Flux<Pojo> data = messageReader.read(ResolvableType.forClass(Pojo.class), request,
+				Collections.emptyMap()).cast(Pojo.class);
+
+		StepVerifier.create(data)
+				.consumeNextWith(pojo -> {
+					assertEquals("foofoo", pojo.getFoo());
+					assertEquals("barbar", pojo.getBar());
+				})
+				.consumeNextWith(pojo -> {
+					assertEquals("foofoofoo", pojo.getFoo());
+					assertEquals("barbarbar", pojo.getBar());
+				})
+				.expectComplete()
+				.verify();
+	}
+
+}