Support multiple async starts in MockHttpServletRequest

Closes gh-33457

Author: bclozel

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java

@@ -44,6 +44,8 @@
 import java.util.stream.Collectors;
 
 import jakarta.servlet.AsyncContext;
+import jakarta.servlet.AsyncEvent;
+import jakarta.servlet.AsyncListener;
 import jakarta.servlet.DispatcherType;
 import jakarta.servlet.RequestDispatcher;
 import jakarta.servlet.ServletConnection;
@@ -920,7 +922,19 @@ public AsyncContext startAsync() {
 	public AsyncContext startAsync(ServletRequest request, @Nullable ServletResponse response) {
 		Assert.state(this.asyncSupported, "Async not supported");
 		this.asyncStarted = true;
-		this.asyncContext = new MockAsyncContext(request, response);
+		MockAsyncContext newAsyncContext = new MockAsyncContext(request, response);
+		if (this.asyncContext != null) {
+			try {
+				AsyncEvent startEvent = new AsyncEvent(newAsyncContext);
+				for (AsyncListener asyncListener : this.asyncContext.getListeners()) {
+					asyncListener.onStartAsync(startEvent);
+				}
+			}
+			catch (IOException ex) {
+				// ignore failures
+			}
+		}
+		this.asyncContext = newAsyncContext;
 		return this.asyncContext;
 	}
 

spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java

@@ -30,6 +30,9 @@
 import java.util.Locale;
 import java.util.Map;
 
+import jakarta.servlet.AsyncContext;
+import jakarta.servlet.AsyncEvent;
+import jakarta.servlet.AsyncListener;
 import jakarta.servlet.http.Cookie;
 import org.junit.jupiter.api.Test;
 
@@ -663,6 +666,44 @@ void httpHeaderFormattedDateError() {
 				request.getDateHeader(HttpHeaders.IF_MODIFIED_SINCE));
 	}
 
+	@Test
+	void shouldRejectAsyncStartsIfUnsupported() {
+		assertThat(request.isAsyncStarted()).isFalse();
+		assertThatIllegalStateException().isThrownBy(request::startAsync);
+	}
+
+	@Test
+	void startAsyncShouldUpdateRequestState() {
+		assertThat(request.isAsyncStarted()).isFalse();
+		request.setAsyncSupported(true);
+		AsyncContext asyncContext = request.startAsync();
+		assertThat(request.isAsyncStarted()).isTrue();
+	}
+
+	@Test
+	void shouldNotifyAsyncListeners() {
+		request.setAsyncSupported(true);
+		AsyncContext asyncContext = request.startAsync();
+		TestAsyncListener testAsyncListener = new TestAsyncListener();
+		asyncContext.addListener(testAsyncListener);
+		asyncContext.complete();
+		assertThat(testAsyncListener.events).hasSize(1);
+		assertThat(testAsyncListener.events.get(0)).extracting("name").isEqualTo("onComplete");
+	}
+
+	@Test
+	void shouldNotifyAsyncListenersWhenNewAsyncStarted() {
+		request.setAsyncSupported(true);
+		AsyncContext asyncContext = request.startAsync();
+		TestAsyncListener testAsyncListener = new TestAsyncListener();
+		asyncContext.addListener(testAsyncListener);
+		AsyncContext newAsyncContext = request.startAsync();
+		assertThat(testAsyncListener.events).hasSize(1);
+		ListenerEvent listenerEvent = testAsyncListener.events.get(0);
+		assertThat(listenerEvent).extracting("name").isEqualTo("onStartAsync");
+		assertThat(listenerEvent.event.getAsyncContext()).isEqualTo(newAsyncContext);
+	}
+
 	private void assertEqualEnumerations(Enumeration<?> enum1, Enumeration<?> enum2) {
 		int count = 0;
 		while (enum1.hasMoreElements()) {
@@ -672,4 +713,31 @@ private void assertEqualEnumerations(Enumeration<?> enum1, Enumeration<?> enum2)
 		}
 	}
 
+	static class TestAsyncListener implements AsyncListener {
+
+		List<ListenerEvent> events = new ArrayList<>();
+
+		@Override
+		public void onComplete(AsyncEvent asyncEvent) throws IOException {
+			this.events.add(new ListenerEvent("onComplete", asyncEvent));
+		}
+
+		@Override
+		public void onTimeout(AsyncEvent asyncEvent) throws IOException {
+			this.events.add(new ListenerEvent("onTimeout", asyncEvent));
+		}
+
+		@Override
+		public void onError(AsyncEvent asyncEvent) throws IOException {
+			this.events.add(new ListenerEvent("onError", asyncEvent));
+		}
+
+		@Override
+		public void onStartAsync(AsyncEvent asyncEvent) throws IOException {
+			this.events.add(new ListenerEvent("onStartAsync", asyncEvent));
+		}
+	}
+
+	record ListenerEvent(String name, AsyncEvent event) {}
+
 }

spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockHttpServletRequest.java

@@ -44,6 +44,8 @@
 import java.util.stream.Collectors;
 
 import jakarta.servlet.AsyncContext;
+import jakarta.servlet.AsyncEvent;
+import jakarta.servlet.AsyncListener;
 import jakarta.servlet.DispatcherType;
 import jakarta.servlet.RequestDispatcher;
 import jakarta.servlet.ServletConnection;
@@ -921,7 +923,19 @@ public AsyncContext startAsync() {
 	public AsyncContext startAsync(ServletRequest request, @Nullable ServletResponse response) {
 		Assert.state(this.asyncSupported, "Async not supported");
 		this.asyncStarted = true;
-		this.asyncContext = new MockAsyncContext(request, response);
+		MockAsyncContext newAsyncContext = new MockAsyncContext(request, response);
+		if (this.asyncContext != null) {
+			try {
+				AsyncEvent startEvent = new AsyncEvent(newAsyncContext);
+				for (AsyncListener asyncListener : this.asyncContext.getListeners()) {
+					asyncListener.onStartAsync(startEvent);
+				}
+			}
+			catch (IOException ex) {
+				// ignore failures
+			}
+		}
+		this.asyncContext = newAsyncContext;
 		return this.asyncContext;
 	}