Improve async support in Spring MVC Test

When obtaining an async result, tests will now await concurrent
processing to complete for the exact amount of time equal to the
actual async timeout value.

Issue: SPR-9875

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/DefaultMvcResult.java

@@ -15,8 +15,15 @@
  */
 package org.springframework.test.web.servlet;
 
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import javax.servlet.http.HttpServletRequest;
+
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.web.context.request.async.WebAsyncManager;
+import org.springframework.web.context.request.async.WebAsyncUtils;
 import org.springframework.web.servlet.FlashMap;
 import org.springframework.web.servlet.HandlerInterceptor;
 import org.springframework.web.servlet.ModelAndView;
@@ -43,6 +50,8 @@ class DefaultMvcResult implements MvcResult {
 
 	private Exception resolvedException;
 
+	private CountDownLatch asyncResultLatch;
+
 
 	/**
 	 * Create a new instance with the given request and response.
@@ -96,4 +105,36 @@ class DefaultMvcResult implements MvcResult {
 		return RequestContextUtils.getOutputFlashMap(mockRequest);
 	}
 
+	public void setAsyncResultLatch(CountDownLatch asyncResultLatch) {
+		this.asyncResultLatch = asyncResultLatch;
+	}
+
+	public Object getAsyncResult() {
+		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(this.mockRequest);
+		if (asyncManager.isConcurrentHandlingStarted()) {
+			if (!awaitAsyncResult()) {
+				throw new IllegalStateException(
+						"Gave up waiting on async result from [" + this.handler + "] to complete");
+			}
+			if (asyncManager.hasConcurrentResult()) {
+				return asyncManager.getConcurrentResult();
+			}
+		}
+
+		return null;
+	}
+
+	private boolean awaitAsyncResult() {
+		if (this.asyncResultLatch == null) {
+			return true;
+		}
+		long timeout = ((HttpServletRequest) this.mockRequest).getAsyncContext().getTimeout();
+		try {
+			return this.asyncResultLatch.await(timeout, TimeUnit.MILLISECONDS);
+		}
+		catch (InterruptedException e) {
+			return false;
+		}
+	}
+
 }

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/MvcResult.java

@@ -75,4 +75,14 @@ public interface MvcResult {
 	 */
 	FlashMap getFlashMap();
 
+	/**
+	 * Get the result of asynchronous execution or {@code null} if concurrent
+	 * handling did not start. This method will hold and await the completion
+	 * of concurrent handling.
+	 *
+	 * @throws IllegalStateException if concurrent handling does not complete
+	 * within the allocated async timeout value.
+	 */
+	Object getAsyncResult();
+
 }

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/TestDispatcherServlet.java

@@ -19,7 +19,6 @@ package org.springframework.test.web.servlet;
 import java.io.IOException;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.TimeUnit;
 
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
@@ -56,32 +55,41 @@ final class TestDispatcherServlet extends DispatcherServlet {
 		super(webApplicationContext);
 	}
 
-	protected DefaultMvcResult getMvcResult(ServletRequest request) {
-		return (DefaultMvcResult) request.getAttribute(MockMvc.MVC_RESULT_ATTRIBUTE);
-	}
-
 	@Override
 	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 
-		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
+		CountDownLatch latch = registerAsyncInterceptors(request);
+		getMvcResult(request).setAsyncResultLatch(latch);
 
-		TestCallableInterceptor callableInterceptor = new TestCallableInterceptor();
-		asyncManager.registerCallableInterceptor("mock-mvc", callableInterceptor);
+		super.service(request, response);
+	}
 
-		TestDeferredResultInterceptor deferredResultInterceptor = new TestDeferredResultInterceptor();
-		asyncManager.registerDeferredResultInterceptor("mock-mvc", deferredResultInterceptor);
+	private CountDownLatch registerAsyncInterceptors(HttpServletRequest request) {
 
-		super.service(request, response);
+		final CountDownLatch asyncResultLatch = new CountDownLatch(1);
+
+		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
 
-		// TODO: add CountDownLatch to DeferredResultInterceptor and wait in request().asyncResult(..)
+		asyncManager.registerCallableInterceptor("mockmvc", new CallableProcessingInterceptor() {
+			public void preProcess(NativeWebRequest request, Callable<?> task) throws Exception { }
+			public void postProcess(NativeWebRequest request, Callable<?> task, Object value) throws Exception {
+				asyncResultLatch.countDown();
+			}
+		});
 
-		Object handler = getMvcResult(request).getHandler();
-		if (asyncManager.isConcurrentHandlingStarted() && !deferredResultInterceptor.wasInvoked) {
-			if (!callableInterceptor.await()) {
-				throw new ServletException(
-						"Gave up waiting on Callable from [" + handler.getClass().getName() + "] to complete");
+		asyncManager.registerDeferredResultInterceptor("mockmvc", new DeferredResultProcessingInterceptor() {
+			public void preProcess(NativeWebRequest request, DeferredResult<?> result) throws Exception { }
+			public void postProcess(NativeWebRequest request, DeferredResult<?> result, Object value) throws Exception {
+				asyncResultLatch.countDown();
 			}
-		}
+			public void afterExpiration(NativeWebRequest request, DeferredResult<?> result) throws Exception { }
+		});
+
+		return asyncResultLatch;
+	}
+
+	protected DefaultMvcResult getMvcResult(ServletRequest request) {
+		return (DefaultMvcResult) request.getAttribute(MockMvc.MVC_RESULT_ATTRIBUTE);
 	}
 
 	@Override
@@ -118,38 +126,4 @@ final class TestDispatcherServlet extends DispatcherServlet {
 		return mav;
 	}
 
-
-	private final class TestCallableInterceptor implements CallableProcessingInterceptor {
-
-		private final CountDownLatch latch = new CountDownLatch(1);
-
-		private boolean await() {
-			try {
-				return this.latch.await(5, TimeUnit.SECONDS);
-			}
-			catch (InterruptedException e) {
-				return false;
-			}
-		}
-
-		public void preProcess(NativeWebRequest request, Callable<?> task) { }
-
-		public void postProcess(NativeWebRequest request, Callable<?> task, Object concurrentResult) {
-			this.latch.countDown();
-		}
-	}
-
-	private final class TestDeferredResultInterceptor implements DeferredResultProcessingInterceptor {
-
-		private boolean wasInvoked;
-
-		public void preProcess(NativeWebRequest request, DeferredResult<?> deferredResult) {
-			this.wasInvoked = true;
-		}
-
-		public void postProcess(NativeWebRequest request, DeferredResult<?> deferredResult, Object concurrentResult) { }
-
-		public void afterExpiration(NativeWebRequest request, DeferredResult<?> deferredResult) { }
-	}
-
 }

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/request/MockAsyncContext.java

@@ -48,7 +48,7 @@ class MockAsyncContext implements AsyncContext {
 
 	private String dispatchedPath;
 
-	private long timeout = 10 * 60 * 1000L;	// 10 seconds is Tomcat's default
+	private long timeout = 10 * 1000L;	// 10 seconds is Tomcat's default
 
 
 	public MockAsyncContext(ServletRequest request, ServletResponse response) {

spring-test-mvc/src/main/java/org/springframework/test/web/servlet/result/RequestResultMatchers.java

@@ -30,8 +30,6 @@ import org.springframework.test.web.servlet.MvcResult;
 import org.springframework.test.web.servlet.ResultMatcher;
 import org.springframework.web.context.request.async.AsyncTask;
 import org.springframework.web.context.request.async.DeferredResult;
-import org.springframework.web.context.request.async.WebAsyncManager;
-import org.springframework.web.context.request.async.WebAsyncUtils;
 
 /**
  * Factory for assertions on the request. An instance of this class is
@@ -90,9 +88,8 @@ public class RequestResultMatchers {
 			@SuppressWarnings("unchecked")
 			public void match(MvcResult result) {
 				HttpServletRequest request = result.getRequest();
-				WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
 				MatcherAssert.assertThat("Async started", request.isAsyncStarted(), equalTo(true));
-				MatcherAssert.assertThat("Async result", (T) asyncManager.getConcurrentResult(), matcher);
+				MatcherAssert.assertThat("Async result", (T) result.getAsyncResult(), matcher);
 			}
 		};
 	}

spring-test-mvc/src/test/java/org/springframework/test/web/servlet/StubMvcResult.java

@@ -120,4 +120,8 @@ public class StubMvcResult implements MvcResult {
 		this.response = response;
 	}
 
+	public Object getAsyncResult() {
+		return null;
+	}
+
 }