Enforce "data: " prefix for outgoing SSE data payloads

Prior to this commit, SSE support in Spring would write payloads with
the "data:" prefix (without space). While this is OK with the standard,
this makes it harder for implementations to support reading and writing
payloads with Spring (the round trip use case).

This commit introduces a breaking change and now enforces "data: " in
all variants. This has the potential of breaking some low level test
suites with text/plain or custom media types, but this should overall
make the situation better for developers.

Closes gh-37242

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/ReactiveReturnTypeTests.java

@@ -52,7 +52,7 @@ class ReactiveReturnTypeTests {
 				.andReturn();
 
 		mockMvc.perform(asyncDispatch(mvcResult))
-				.andExpect(content().string("data:event0\n\ndata:event1\n\ndata:event2\n\n"));
+				.andExpect(content().string("data: event0\n\ndata: event1\n\ndata: event2\n\n"));
 	}
 
 

spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java

@@ -96,7 +96,7 @@ public final class ServerSentEvent<T> {
 
 	/**
 	 * Return a StringBuilder with the id, event, retry, and comment fields fully
-	 * serialized, and also appending "data:" if there is data.
+	 * serialized, and also appending "data: " if there is data.
 	 * @since 6.2.1
 	 */
 	public String format() {
@@ -116,7 +116,7 @@ public final class ServerSentEvent<T> {
 			sb.append('\n');
 		}
 		if (this.data != null) {
-			sb.append("data:");
+			sb.append("data: ");
 		}
 		return sb.toString();
 	}

spring-web/src/main/java/org/springframework/http/codec/json/Jackson2JsonEncoder.java

@@ -69,7 +69,7 @@ public class Jackson2JsonEncoder extends AbstractJackson2Encoder {
 
 	private static PrettyPrinter initSsePrettyPrinter() {
 		DefaultPrettyPrinter printer = new DefaultPrettyPrinter();
-		printer.indentObjectsWith(new DefaultIndenter("  ", "\ndata:"));
+		printer.indentObjectsWith(new DefaultIndenter("  ", "\ndata: "));
 		return printer;
 	}
 

spring-web/src/main/java/org/springframework/http/codec/json/JacksonJsonEncoder.java

@@ -117,7 +117,7 @@ public class JacksonJsonEncoder extends AbstractJacksonEncoder<JsonMapper> {
 
 	private static PrettyPrinter initSsePrettyPrinter() {
 		DefaultPrettyPrinter printer = new DefaultPrettyPrinter();
-		printer.indentObjectsWith(new DefaultIndenter("  ", "\ndata:"));
+		printer.indentObjectsWith(new DefaultIndenter("  ", "\ndata: "));
 		return printer;
 	}
 

spring-web/src/main/java/org/springframework/http/converter/AbstractJacksonHttpMessageConverter.java

@@ -175,7 +175,7 @@ public abstract class AbstractJacksonHttpMessageConverter<T extends ObjectMapper
 
 	private PrettyPrinter initSsePrettyPrinter() {
 		DefaultPrettyPrinter prettyPrinter = new DefaultPrettyPrinter();
-		prettyPrinter.indentObjectsWith(new DefaultIndenter("  ", "\ndata:"));
+		prettyPrinter.indentObjectsWith(new DefaultIndenter("  ", "\ndata: "));
 		return prettyPrinter;
 	}
 

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -108,7 +108,7 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 	protected AbstractJackson2HttpMessageConverter(ObjectMapper objectMapper) {
 		this.defaultObjectMapper = objectMapper;
 		DefaultPrettyPrinter prettyPrinter = new DefaultPrettyPrinter();
-		prettyPrinter.indentObjectsWith(new DefaultIndenter("  ", "\ndata:"));
+		prettyPrinter.indentObjectsWith(new DefaultIndenter("  ", "\ndata: "));
 		this.ssePrettyPrinter = prettyPrinter;
 	}
 

spring-web/src/main/java/org/springframework/web/util/SseUtils.java

@@ -31,9 +31,9 @@ public abstract class SseUtils {
 	/**
 	 * Append {@code value} to {@code output}, replacing each line separator
 	 * ({@code "\n"}, {@code "\r"}, or {@code "\r\n"}) it contains with a new
-	 * {@code field} line (that is, {@code "\n" + field + ":"}). This keeps a
+	 * {@code field} line (that is, {@code "\n" + field + ": "}, or
-	 * multi-line field value from breaking out of the current SSE field when
+	 * {@code "\n:"} for a comment). This keeps a multi-line field value from
-	 * written on the wire.
+	 * breaking out of the current SSE field when written on the wire.
 	 * @param field the name of the SSE field that {@code value} belongs to
 	 * (for example, {@code "data"}), or an empty string for a comment
 	 * @param value the field value to escape and append
@@ -44,7 +44,7 @@ public abstract class SseUtils {
 			output.append(value);
 			return;
 		}
-		String lineSeparatorReplacement = "\n" + field + ":";
+		String lineSeparatorReplacement = "\n" + field + (field.isEmpty() ? ":" : ": ");
 		int length = value.length();
 		for (int i = 0; i < length; i++) {
 			char c = value.charAt(i);

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

@@ -85,7 +85,7 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 
 		StepVerifier.create(outputMessage.getBody())
 				.consumeNextWith(stringConsumer(
-						"id:c42\nevent:foo\nretry:123\n:bla\n:bla bla\n:bla bla bla\ndata:bar\n\n"))
+						"id:c42\nevent:foo\nretry:123\n:bla\n:bla bla\n:bla bla bla\ndata: bar\n\n"))
 				.expectComplete()
 				.verify();
 	}
@@ -99,8 +99,8 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 		testWrite(source, outputMessage, String.class);
 
 		StepVerifier.create(outputMessage.getBody())
-				.consumeNextWith(stringConsumer("data:foo\n\n"))
+				.consumeNextWith(stringConsumer("data: foo\n\n"))
-				.consumeNextWith(stringConsumer("data:bar\n\n"))
+				.consumeNextWith(stringConsumer("data: bar\n\n"))
 				.expectComplete()
 				.verify();
 	}
@@ -114,9 +114,9 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 		testWrite(source, outputMessage, String.class);
 
 		StepVerifier.create(outputMessage.getBody())
-				.consumeNextWith(stringConsumer("data:first\ndata:second\n\n"))
+				.consumeNextWith(stringConsumer("data: first\ndata: second\n\n"))
-				.consumeNextWith(stringConsumer("data:first\ndata:second\n\n"))
+				.consumeNextWith(stringConsumer("data: first\ndata: second\n\n"))
-				.consumeNextWith(stringConsumer("data:first\ndata:second\n\n"))
+				.consumeNextWith(stringConsumer("data: first\ndata: second\n\n"))
 				.expectComplete()
 				.verify();
 	}
@@ -136,7 +136,7 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 				.consumeNextWith(dataBuffer -> {
 					String value = dataBuffer.toString(charset);
 					DataBufferUtils.release(dataBuffer);
-					assertThat(value).isEqualTo("data:\u00A3\n\n");
+					assertThat(value).isEqualTo("data: \u00A3\n\n");
 				})
 				.expectComplete()
 				.verify();
@@ -151,10 +151,10 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 		testWrite(source, outputMessage, Pojo.class);
 
 		StepVerifier.create(outputMessage.getBody())
-				.consumeNextWith(stringConsumer("data:"))
+				.consumeNextWith(stringConsumer("data: "))
 				.consumeNextWith(stringConsumer("{\"foo\":\"foofoo\",\"bar\":\"barbar\"}"))
 				.consumeNextWith(stringConsumer("\n\n"))
-				.consumeNextWith(stringConsumer("data:"))
+				.consumeNextWith(stringConsumer("data: "))
 				.consumeNextWith(stringConsumer("{\"foo\":\"foofoofoo\",\"bar\":\"barbarbar\"}"))
 				.consumeNextWith(stringConsumer("\n\n"))
 				.expectComplete()
@@ -173,19 +173,19 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 		testWrite(source, outputMessage, Pojo.class);
 
 		StepVerifier.create(outputMessage.getBody())
-				.consumeNextWith(stringConsumer("data:"))
+				.consumeNextWith(stringConsumer("data: "))
 				.consumeNextWith(stringConsumer("""
 						{
-						data:  "foo" : "foofoo",
+						data:   "foo" : "foofoo",
-						data:  "bar" : "barbar"
+						data:   "bar" : "barbar"
-						data:}"""))
+						data: }"""))
 				.consumeNextWith(stringConsumer("\n\n"))
-				.consumeNextWith(stringConsumer("data:"))
+				.consumeNextWith(stringConsumer("data: "))
 				.consumeNextWith(stringConsumer("""
 						{
-						data:  "foo" : "foofoofoo",
+						data:   "foo" : "foofoofoo",
-						data:  "bar" : "barbarbar"
+						data:   "bar" : "barbarbar"
-						data:}"""))
+						data: }"""))
 				.consumeNextWith(stringConsumer("\n\n"))
 				.expectComplete()
 				.verify();
@@ -203,7 +203,7 @@ class ServerSentEventHttpMessageWriterTests extends AbstractDataBufferAllocating
 
 		assertThat(outputMessage.getHeaders().getContentType()).isEqualTo(mediaType);
 		StepVerifier.create(outputMessage.getBody())
-				.consumeNextWith(stringConsumer("data:", charset))
+				.consumeNextWith(stringConsumer("data: ", charset))
 				.consumeNextWith(stringConsumer("{\"foo\":\"foo\uD834\uDD1E\",\"bar\":\"bar\uD834\uDD1E\"}", charset))
 				.consumeNextWith(stringConsumer("\n\n", charset))
 				.expectComplete()

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

@@ -51,7 +51,7 @@ class ServerSentEventTests {
 	void supportMultiLineComments(String newLine, String description) {
 		ServerSentEvent<String> event = ServerSentEvent.<String>builder()
 				.comment("foo" + newLine + "bar" + newLine + "baz").data("payload").build();
-		assertThat(event.format()).isEqualTo(":foo\n:bar\n:baz\ndata:");
+		assertThat(event.format()).isEqualTo(":foo\n:bar\n:baz\ndata: ");
 	}
 
 	private static Stream<Arguments> newLineCharacters() {

spring-web/src/test/java/org/springframework/http/converter/json/JacksonJsonHttpMessageConverterTests.java

@@ -415,7 +415,7 @@ class JacksonJsonHttpMessageConverterTests {
 				MediaType.APPLICATION_JSON, outputMessage, null);
 		String result = outputMessage.getBodyAsString(StandardCharsets.UTF_8);
 
-		assertThat(result).isEqualTo("{\ndata:  \"name\" : \"Jason\"\ndata:}");
+		assertThat(result).isEqualTo("{\ndata:   \"name\" : \"Jason\"\ndata: }");
 	}
 
 	@Test

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -385,7 +385,7 @@ class MappingJackson2HttpMessageConverterTests {
 		this.converter.writeInternal(bean, null, outputMessage);
 		String result = outputMessage.getBodyAsString(StandardCharsets.UTF_8);
 
-		assertThat(result).isEqualTo("{\ndata:  \"name\" : \"Jason\"\ndata:}");
+		assertThat(result).isEqualTo("{\ndata:   \"name\" : \"Jason\"\ndata: }");
 	}
 
 	@Test

spring-web/src/test/java/org/springframework/web/util/SseUtilsTests.java

@@ -44,9 +44,9 @@ class SseUtilsTests {
 	@MethodSource("newLineCharacters")
 	void appendFieldValueReplacesLineSeparatorWithFieldPrefix(String newLine, String description) {
 		StringBuilder sb = new StringBuilder();
-		sb.append("data:");
+		sb.append("data: ");
 		SseUtils.appendFieldValue("data", "first" + newLine + "second", sb);
-		assertThat(sb).hasToString("data:first\ndata:second");
+		assertThat(sb).hasToString("data: first\ndata: second");
 	}
 
 	@ParameterizedTest(name = "{1}")

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/ViewResolutionResultHandler.java

@@ -590,7 +590,7 @@ public class ViewResolutionResultHandler extends HandlerResultHandlerSupport imp
 
 			ServerSentEvent<?> sse = (ServerSentEvent<?>) hints;
 			CharSequence eventText = (sse != null ? sse.format() :
-					(fragment.viewName() != null ? "event:" + fragment.viewName() + "\n" : "") + "data:");
+					(fragment.viewName() != null ? "event:" + fragment.viewName() + "\n" : "") + "data: ");
 
 			DataBuffer prefix = encodeText(eventText.toString(), charset, bufferFactory);
 			DataBuffer suffix = encodeText("\n\n", charset, bufferFactory);

spring-webflux/src/test/java/org/springframework/web/reactive/result/view/FragmentViewResolutionResultHandlerTests.java

@@ -107,14 +107,14 @@ class FragmentViewResolutionResultHandlerTests {
 				on(Handler.class).resolveReturnType(Flux.class, Fragment.class),
 				"""
 				event:fragment1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data:</p>
+				data: </p>
 
 				event:fragment2
-				data:<p>
+				data: <p>
-				data:	Hello Bar
+				data: 	Hello Bar
-				data:</p>
+				data: </p>
 
 				""");
 	}
@@ -126,10 +126,10 @@ class FragmentViewResolutionResultHandlerTests {
 				on(Handler.class).resolveReturnType(Flux.class, Fragment.class),
 				"""
 				event:fragment1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data: and Bar
+				data:  and Bar
-				data:</p>
+				data: </p>
 
 				""");
 	}
@@ -147,15 +147,15 @@ class FragmentViewResolutionResultHandlerTests {
 				"""
 				id:id1
 				event:event1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data:</p>
+				data: </p>
 
 				id:id2
 				event:event2
-				data:<p>
+				data: <p>
-				data:	Hello Bar
+				data: 	Hello Bar
-				data:</p>
+				data: </p>
 
 				""");
 	}

spring-webmvc/src/main/java/org/springframework/web/servlet/function/SseServerResponse.java

@@ -177,6 +177,9 @@ final class SseServerResponse extends AbstractServerResponse {
 
 		private SseBuilder field(String name, String value) {
 			this.builder.append(name).append(':');
+			if (!name.isEmpty()) {
+				this.builder.append(' ');
+			}
 			SseUtils.appendFieldValue(name, value, this.builder);
 			this.builder.append('\n');
 			return this;
@@ -200,7 +203,7 @@ final class SseServerResponse extends AbstractServerResponse {
 
 		@SuppressWarnings("unchecked")
 		private void writeObject(Object data) throws IOException {
-			this.builder.append("data:");
+			this.builder.append("data: ");
 			try {
 				this.outputMessage.getBody().write(builderBytes());
 				Class<?> dataClass = data.getClass();

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitter.java

@@ -240,7 +240,7 @@ public class SseEmitter extends ResponseBodyEmitter {
 			if (object instanceof ModelAndView mav && !this.hasName && mav.getViewName() != null) {
 				name(mav.getViewName());
 			}
-			append("data:");
+			append("data: ");
 			saveAppendedText(TEXT_PLAIN);
 			if (object instanceof String text) {
 				writeStringData(text, mediaType);

spring-webmvc/src/test/java/org/springframework/web/servlet/function/SseServerResponseTests.java

@@ -71,7 +71,7 @@ class SseServerResponseTests {
 		ModelAndView mav = response.writeTo(this.mockRequest, this.mockResponse, context);
 		assertThat(mav).isNull();
 
-		String expected = "data:" + body + "\n\n";
+		String expected = "data: " + body + "\n\n";
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
 	}
 
@@ -127,7 +127,7 @@ class SseServerResponseTests {
 		ModelAndView mav = response.writeTo(this.mockRequest, this.mockResponse, context);
 		assertThat(mav).isNull();
 
-		String expected = "data:{\"name\":\"John Doe\",\"age\":42}\n\n";
+		String expected = "data: {\"name\":\"John Doe\",\"age\":42}\n\n";
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
 	}
 
@@ -151,10 +151,10 @@ class SseServerResponseTests {
 		assertThat(mav).isNull();
 
 		String expected = """
-				data:{
+				data: {
-				data:  "name" : "John Doe",
+				data:   "name" : "John Doe",
-				data:  "age" : 42
+				data:   "age" : 42
-				data:}
+				data: }
 
 				""";
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
@@ -186,7 +186,7 @@ class SseServerResponseTests {
 				:comment line 1
 				:comment line 2
 				retry:1000
-				data:data
+				data: data
 
 				""";
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
@@ -229,7 +229,7 @@ class SseServerResponseTests {
 		ModelAndView mav = response.writeTo(this.mockRequest, this.mockResponse, context);
 		assertThat(mav).isNull();
 
-		String expected = "data:line1\ndata:line2\ndata:line3\n\n";
+		String expected = "data: line1\ndata: line2\ndata: line3\n\n";
 		assertThat(this.mockResponse.getContentAsString()).isEqualTo(expected);
 	}
 

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/FragmentRenderingStreamTests.java

@@ -104,14 +104,14 @@ class FragmentRenderingStreamTests {
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
 		assertThat(this.response.getContentAsString()).isEqualTo(("""
 				event:fragment1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data:</p>
+				data: </p>
 
 				event:fragment2
-				data:<p>
+				data: <p>
-				data:	Hello Bar
+				data: 	Hello Bar
-				data:</p>
+				data: </p>
 
 				"""));
 	}
@@ -134,14 +134,14 @@ class FragmentRenderingStreamTests {
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
 		assertThat(this.response.getContentAsString()).isEqualTo(("""
 				event:fragment1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data:</p>
+				data: </p>
 
 				event:fragment2
-				data:<p>
+				data: <p>
-				data:	Hello Bar
+				data: 	Hello Bar
-				data:</p>
+				data: </p>
 
 				"""));
 	}
@@ -163,10 +163,10 @@ class FragmentRenderingStreamTests {
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
 		assertThat(this.response.getContentAsString()).isEqualTo(("""
 				event:fragment1
-				data:<p>
+				data: <p>
-				data:	Hello Foo
+				data: 	Hello Foo
-				data: and Bar
+				data:  and Bar
-				data:</p>
+				data: </p>
 
 				"""));
 	}

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ReactiveTypeHandlerTests.java

@@ -267,7 +267,7 @@ class ReactiveTypeHandlerTests {
 		sink.tryEmitNext("baz");
 		sink.tryEmitComplete();
 
-		assertThat(emitterHandler.getValuesAsText()).isEqualTo("data:foo\n\ndata:bar\n\ndata:baz\n\n");
+		assertThat(emitterHandler.getValuesAsText()).isEqualTo("data: foo\n\ndata: bar\n\ndata: baz\n\n");
 	}
 
 	@Test
@@ -286,7 +286,7 @@ class ReactiveTypeHandlerTests {
 		sink.tryEmitNext(ServerSentEvent.builder("baz").id("3").build());
 		sink.tryEmitComplete();
 
-		assertThat(emitterHandler.getValuesAsText()).isEqualTo("id:1\ndata:foo\n\nid:2\ndata:bar\n\nid:3\ndata:baz\n\n");
+		assertThat(emitterHandler.getValuesAsText()).isEqualTo("id:1\ndata: foo\n\nid:2\ndata: bar\n\nid:3\ndata: baz\n\n");
 	}
 
 	@ParameterizedTest
@@ -453,7 +453,7 @@ class ReactiveTypeHandlerTests {
 
 			sink.tryEmitComplete();
 
-			assertThat(emitterHandler.getValuesAsText()).isEqualTo("data:emitted value\n\n");
+			assertThat(emitterHandler.getValuesAsText()).isEqualTo("data: emitted value\n\n");
 			assertThat(emitterHandler.getSavedRequest()).isSameAs(this.servletRequest);
 		}
 		finally {

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapterTests.java

@@ -218,7 +218,7 @@ class RequestMappingHandlerAdapterTests {
 
 		assertThat(this.response.getStatus()).isEqualTo(200);
 		assertThat(this.response.getHeader("Content-Type")).isEqualTo("text/event-stream");
-		assertThat(this.response.getContentAsString()).isEqualTo("data:event 1\n\ndata:event 2\n\n");
+		assertThat(this.response.getContentAsString()).isEqualTo("data: event 1\n\ndata: event 2\n\n");
 	}
 
 	@Test

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ResponseBodyEmitterReturnValueHandlerTests.java

@@ -218,8 +218,8 @@ class ResponseBodyEmitterReturnValueHandlerTests {
 				event:update
 				id:1
 				retry:5000
-				data:{"id":1,"name":"Joe"}
+				data: {"id":1,"name":"Joe"}
-				data:{"id":2,"name":"John"}
+				data: {"id":2,"name":"John"}
 
 				"""));
 	}
@@ -235,7 +235,7 @@ class ResponseBodyEmitterReturnValueHandlerTests {
 		assertThat(this.response.getStatus()).isEqualTo(200);
 
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
-		assertThat(this.response.getContentAsString()).isEqualTo("data:foo\n\ndata:bar\n\ndata:baz\n\n");
+		assertThat(this.response.getContentAsString()).isEqualTo("data: foo\n\ndata: bar\n\ndata: baz\n\n");
 	}
 
 	@Test
@@ -274,7 +274,7 @@ class ResponseBodyEmitterReturnValueHandlerTests {
 		assertThat(this.response.getStatus()).isEqualTo(200);
 
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
-		assertThat(this.response.getContentAsString()).isEqualTo("data:foo123\n\ndata:bar123\n\ndata:baz123\n\n");
+		assertThat(this.response.getContentAsString()).isEqualTo("data: foo123\n\ndata: bar123\n\ndata: baz123\n\n");
 	}
 
 	@Test // gh-21972
@@ -357,7 +357,7 @@ class ResponseBodyEmitterReturnValueHandlerTests {
 		assertThat(this.request.isAsyncStarted()).isTrue();
 		assertThat(this.response.getStatus()).isEqualTo(200);
 		assertThat(this.response.getContentType()).isEqualTo("text/event-stream");
-		assertThat(this.response.getContentAsString()).isEqualTo("data:foo\n\ndata:bar\n\n");
+		assertThat(this.response.getContentAsString()).isEqualTo("data: foo\n\ndata: bar\n\n");
 	}
 
 	@Test // gh-36357

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/SseEmitterTests.java

@@ -65,7 +65,7 @@ class SseEmitterTests {
 	void send() throws Exception {
 		this.emitter.send("foo");
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo");
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -75,7 +75,7 @@ class SseEmitterTests {
 	void sendWithMediaType() throws Exception {
 		this.emitter.send("foo", MediaType.TEXT_PLAIN);
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo", MediaType.TEXT_PLAIN);
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -92,7 +92,7 @@ class SseEmitterTests {
 	void sendEventWithDataLine() throws Exception {
 		this.emitter.send(event().data("foo"));
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo");
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -102,9 +102,9 @@ class SseEmitterTests {
 	void sendEventWithTwoDataLines() throws Exception {
 		this.emitter.send(event().data("foo").data("bar"));
 		this.handler.assertSentObjectCount(5);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo");
-		this.handler.assertObject(2, "\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(2, "\ndata: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(3, "bar");
 		this.handler.assertObject(4, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -115,8 +115,8 @@ class SseEmitterTests {
 	void sendEventWithMultiline(String newLineChars, String description) throws Exception {
 		this.emitter.send(event().data("foo" + newLineChars + "bar" + newLineChars + "baz"));
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
-		this.handler.assertObject(1, "foo\ndata:bar\ndata:baz");
+		this.handler.assertObject(1, "foo\ndata: bar\ndata: baz");
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
 	}
@@ -126,8 +126,8 @@ class SseEmitterTests {
 	void sendEventWithMultilineWithMediaType(String newLineChars, String description) throws Exception {
 		this.emitter.send(event().data("foo" + newLineChars + "bar" + newLineChars + "baz", MediaType.TEXT_PLAIN));
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, "data:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, "data: ", TEXT_PLAIN_UTF8);
-		this.handler.assertObject(1, "foo\ndata:bar\ndata:baz", MediaType.TEXT_PLAIN);
+		this.handler.assertObject(1, "foo\ndata: bar\ndata: baz", MediaType.TEXT_PLAIN);
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
 	}
@@ -136,7 +136,7 @@ class SseEmitterTests {
 	void sendEventFull() throws Exception {
 		this.emitter.send(event().comment("blah").name("test").reconnectTime(5000L).id("1").data("foo"));
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, ":blah\nevent:test\nretry:5000\nid:1\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, ":blah\nevent:test\nretry:5000\nid:1\ndata: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo");
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -146,9 +146,9 @@ class SseEmitterTests {
 	void sendEventFullWithTwoDataLinesInTheMiddle() throws Exception {
 		this.emitter.send(event().comment("blah").data("foo").data("bar").name("test").reconnectTime(5000L).id("1"));
 		this.handler.assertSentObjectCount(5);
-		this.handler.assertObject(0, ":blah\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, ":blah\ndata: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "foo");
-		this.handler.assertObject(2, "\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(2, "\ndata: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(3, "bar");
 		this.handler.assertObject(4, "\nevent:test\nretry:5000\nid:1\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);
@@ -173,7 +173,7 @@ class SseEmitterTests {
 	void supportMultiLineComments(String newLineChars, String description) throws Exception {
 		this.emitter.send(event().comment("foo" + newLineChars + "bar" + newLineChars + "baz").data("payload"));
 		this.handler.assertSentObjectCount(3);
-		this.handler.assertObject(0, ":foo\n:bar\n:baz\ndata:", TEXT_PLAIN_UTF8);
+		this.handler.assertObject(0, ":foo\n:bar\n:baz\ndata: ", TEXT_PLAIN_UTF8);
 		this.handler.assertObject(1, "payload");
 		this.handler.assertObject(2, "\n\n", TEXT_PLAIN_UTF8);
 		this.handler.assertWriteCount(1);