Revised InvocableHandlerMethod exception messages (controller vs endpoint vs handler)

Introduces dedicated MethodArgumentResolutionException for spring-messaging invocations.

Issue: SPR-15139

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractMethodArgumentResolutionException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -18,7 +18,7 @@ package org.springframework.messaging.handler.annotation.support;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.messaging.Message;
-import org.springframework.messaging.MessagingException;
+import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;
 
 /**
  * Base class for exceptions resulting from the invocation of
@@ -26,43 +26,24 @@ import org.springframework.messaging.MessagingException;
  *
  * @author Rossen Stoyanchev
  * @since 4.0.3
+ * @deprecated as of 4.3.6, in favor of the invocation-associated
+ * {@link MethodArgumentResolutionException}
  */
+@Deprecated
 @SuppressWarnings("serial")
-public abstract class AbstractMethodArgumentResolutionException extends MessagingException {
+public abstract class AbstractMethodArgumentResolutionException extends MethodArgumentResolutionException {
 
-	private final MethodParameter parameter;
-
-
-	/**
-	 * Create a new instance providing the invalid {@code MethodParameter}.
-	 */
 	protected AbstractMethodArgumentResolutionException(Message<?> message, MethodParameter parameter) {
-		this(message, parameter, getMethodParamMessage(parameter));
+		super(message, parameter);
 	}
 
-	/**
-	 * Create a new instance providing the invalid {@code MethodParameter} and
-	 * a prepared description. Subclasses should prepend the description with
-	 * the help of {@link #getMethodParamMessage(org.springframework.core.MethodParameter)}.
-	 */
-	protected AbstractMethodArgumentResolutionException(Message<?> message, MethodParameter param, String description) {
-		super(message, description);
-		this.parameter = param;
-	}
-
-
-	/**
-	 * Return the MethodParameter that was rejected.
-	 */
-	public final MethodParameter getMethodParameter() {
-		return this.parameter;
+	protected AbstractMethodArgumentResolutionException(Message<?> message, MethodParameter parameter, String description) {
+		super(message, parameter, description);
 	}
 
 
 	protected static String getMethodParamMessage(MethodParameter param) {
-		return new StringBuilder("Could not resolve method parameter at index ")
-				.append(param.getParameterIndex()).append(" in method: ")
-				.append(param.getMethod().toGenericString()).append(" ").toString();
+		return "";
 	}
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MethodArgumentNotValidException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -29,27 +29,25 @@ import org.springframework.validation.ObjectError;
  * @author Rossen Stoyanchev
  * @since 4.0.1
  */
-@SuppressWarnings("serial")
+@SuppressWarnings({"serial", "deprecation"})
 public class MethodArgumentNotValidException extends AbstractMethodArgumentResolutionException {
 
-	private final BindingResult bindingResult;
+	private BindingResult bindingResult;
 
 
 	/**
 	 * Create a new instance with the invalid {@code MethodParameter}.
 	 */
 	public MethodArgumentNotValidException(Message<?> message, MethodParameter parameter) {
-		this(message, parameter, null);
+		super(message, parameter);
 	}
 
 	/**
 	 * Create a new instance with the invalid {@code MethodParameter} and a
 	 * {@link org.springframework.validation.BindingResult}.
 	 */
-	public MethodArgumentNotValidException(Message<?> message, MethodParameter parameter,
-			BindingResult bindingResult) {
-
-		super(message, parameter, getMethodParamMessage(parameter) + getValidationErrorMessage(bindingResult));
+	public MethodArgumentNotValidException(Message<?> message, MethodParameter parameter, BindingResult bindingResult) {
+		super(message, parameter, getValidationErrorMessage(bindingResult));
 		this.bindingResult = bindingResult;
 	}
 
@@ -64,17 +62,12 @@ public class MethodArgumentNotValidException extends AbstractMethodArgumentResol
 
 
 	private static String getValidationErrorMessage(BindingResult bindingResult) {
-		if (bindingResult != null) {
-			StringBuilder sb = new StringBuilder();
-			sb.append(", with ").append(bindingResult.getErrorCount()).append(" error(s): ");
-			for (ObjectError error : bindingResult.getAllErrors()) {
-				sb.append("[").append(error).append("] ");
-			}
-			return sb.toString();
-		}
-		else {
-			return "";
+		StringBuilder sb = new StringBuilder();
+		sb.append(bindingResult.getErrorCount()).append(" error(s): ");
+		for (ObjectError error : bindingResult.getAllErrors()) {
+			sb.append("[").append(error).append("] ");
 		}
+		return sb.toString();
 	}
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/MethodArgumentTypeMismatchException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -20,20 +20,16 @@ import org.springframework.core.MethodParameter;
 import org.springframework.messaging.Message;
 
 /**
- * Exception that indicates that a method argument has not the
- * expected type.
+ * Exception that indicates that a method argument has not the expected type.
  *
  * @author Stephane Nicoll
  * @since 4.0.3
  */
-@SuppressWarnings("serial")
+@SuppressWarnings({"serial", "deprecation"})
 public class MethodArgumentTypeMismatchException extends AbstractMethodArgumentResolutionException {
 
-	/**
-	 * Create a new instance with the invalid {@code MethodParameter}.
-	 */
-	public MethodArgumentTypeMismatchException(Message<?> message, MethodParameter param, String description) {
-		super(message, param, getMethodParamMessage(param) + description);
+	public MethodArgumentTypeMismatchException(Message<?> message, MethodParameter parameter, String description) {
+		super(message, parameter, description);
 	}
 
 }

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/InvocableHandlerMethod.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -139,36 +139,22 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				}
 				catch (Exception ex) {
 					if (logger.isDebugEnabled()) {
-						logger.debug(getArgumentResolutionErrorMessage("Error resolving argument", i), ex);
+						logger.debug(getArgumentResolutionErrorMessage("Failed to resolve", i), ex);
 					}
 					throw ex;
 				}
 			}
 			if (args[i] == null) {
-				String msg = getArgumentResolutionErrorMessage("No suitable resolver for argument", i);
-				throw new IllegalStateException(msg);
+				throw new MethodArgumentResolutionException(message, parameter,
+						getArgumentResolutionErrorMessage("No suitable resolver for", i));
 			}
 		}
 		return args;
 	}
 
-	private String getArgumentResolutionErrorMessage(String message, int index) {
-		MethodParameter param = getMethodParameters()[index];
-		message += " [" + index + "] [type=" + param.getParameterType().getName() + "]";
-		return getDetailedErrorMessage(message);
-	}
-
-	/**
-	 * Adds HandlerMethod details such as the controller type and method
-	 * signature to the given error message.
-	 * @param message error message to append the HandlerMethod details to
-	 */
-	protected String getDetailedErrorMessage(String message) {
-		StringBuilder sb = new StringBuilder(message).append("\n");
-		sb.append("HandlerMethod details: \n");
-		sb.append("Controller [").append(getBeanType().getName()).append("]\n");
-		sb.append("Method [").append(getBridgedMethod().toGenericString()).append("]\n");
-		return sb.toString();
+	private String getArgumentResolutionErrorMessage(String text, int index) {
+		Class<?> paramType = getMethodParameters()[index].getParameterType();
+		return text + " argument " + index + " of type '" + paramType.getName() + "'";
 	}
 
 	/**
@@ -197,8 +183,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		}
 		catch (IllegalArgumentException ex) {
 			assertTargetBean(getBridgedMethod(), getBean(), args);
-			String message = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
-			throw new IllegalStateException(getInvocationErrorMessage(message, args), ex);
+			String text = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
+			throw new IllegalStateException(getInvocationErrorMessage(text, args), ex);
 		}
 		catch (InvocationTargetException ex) {
 			// Unwrap for HandlerExceptionResolvers ...
@@ -213,33 +199,33 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				throw (Exception) targetException;
 			}
 			else {
-				String msg = getInvocationErrorMessage("Failed to invoke controller method", args);
-				throw new IllegalStateException(msg, targetException);
+				String text = getInvocationErrorMessage("Failed to invoke handler method", args);
+				throw new IllegalStateException(text, targetException);
 			}
 		}
 	}
 
 	/**
 	 * Assert that the target bean class is an instance of the class where the given
-	 * method is declared. In some cases the actual controller instance at request-
+	 * method is declared. In some cases the actual endpoint instance at request-
 	 * processing time may be a JDK dynamic proxy (lazy initialization, prototype
-	 * beans, and others). {@code @Controller}'s that require proxying should prefer
+	 * beans, and others). Endpoint classes that require proxying should prefer
 	 * class-based proxy mechanisms.
 	 */
 	private void assertTargetBean(Method method, Object targetBean, Object[] args) {
 		Class<?> methodDeclaringClass = method.getDeclaringClass();
 		Class<?> targetBeanClass = targetBean.getClass();
 		if (!methodDeclaringClass.isAssignableFrom(targetBeanClass)) {
-			String msg = "The mapped controller method class '" + methodDeclaringClass.getName() +
-					"' is not an instance of the actual controller bean class '" +
-					targetBeanClass.getName() + "'. If the controller requires proxying " +
+			String text = "The mapped handler method class '" + methodDeclaringClass.getName() +
+					"' is not an instance of the actual endpoint bean class '" +
+					targetBeanClass.getName() + "'. If the endpoint requires proxying " +
 					"(e.g. due to @Transactional), please use class-based proxying.";
-			throw new IllegalStateException(getInvocationErrorMessage(msg, args));
+			throw new IllegalStateException(getInvocationErrorMessage(text, args));
 		}
 	}
 
-	private String getInvocationErrorMessage(String message, Object[] resolvedArgs) {
-		StringBuilder sb = new StringBuilder(getDetailedErrorMessage(message));
+	private String getInvocationErrorMessage(String text, Object[] resolvedArgs) {
+		StringBuilder sb = new StringBuilder(getDetailedErrorMessage(text));
 		sb.append("Resolved arguments: \n");
 		for (int i = 0; i < resolvedArgs.length; i++) {
 			sb.append("[").append(i).append("] ");
@@ -254,6 +240,19 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		return sb.toString();
 	}
 
+	/**
+	 * Adds HandlerMethod details such as the bean type and method signature to the message.
+	 * @param text error message to append the HandlerMethod details to
+	 */
+	protected String getDetailedErrorMessage(String text) {
+		StringBuilder sb = new StringBuilder(text).append("\n");
+		sb.append("HandlerMethod details: \n");
+		sb.append("Endpoint [").append(getBeanType().getName()).append("]\n");
+		sb.append("Method [").append(getBridgedMethod().toGenericString()).append("]\n");
+		return sb.toString();
+	}
+
+
 	MethodParameter getAsyncReturnValueType(Object returnValue) {
 		return new AsyncResultMethodParameter(returnValue);
 	}
@@ -268,7 +267,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		public AsyncResultMethodParameter(Object returnValue) {
 			super(-1);
 			this.returnValue = returnValue;
-			this.returnType = ResolvableType.forType(super.getGenericParameterType()).getGeneric(0);
+			this.returnType = ResolvableType.forType(super.getGenericParameterType()).getGeneric();
 		}
 
 		protected AsyncResultMethodParameter(AsyncResultMethodParameter original) {

spring-messaging/src/main/java/org/springframework/messaging/handler/invocation/MethodArgumentResolutionException.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2002-2017 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.messaging.handler.invocation;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.MessagingException;
+
+/**
+ * Common exception resulting from the invocation of
+ * {@link org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver}.
+ *
+ * @author Juergen Hoeller
+ * @since 4.3.6
+ * @see HandlerMethodArgumentResolver
+ */
+@SuppressWarnings("serial")
+public class MethodArgumentResolutionException extends MessagingException {
+
+	private final MethodParameter parameter;
+
+
+	/**
+	 * Create a new instance providing the invalid {@code MethodParameter}.
+	 */
+	public MethodArgumentResolutionException(Message<?> message, MethodParameter parameter) {
+		super(message, getMethodParameterMessage(parameter));
+		this.parameter = parameter;
+	}
+
+	/**
+	 * Create a new instance providing the invalid {@code MethodParameter} and
+	 * a prepared description.
+	 */
+	public MethodArgumentResolutionException(Message<?> message, MethodParameter parameter, String description) {
+		super(message, getMethodParameterMessage(parameter) + ": " + description);
+		this.parameter = parameter;
+	}
+
+
+	/**
+	 * Return the MethodParameter that was rejected.
+	 */
+	public final MethodParameter getMethodParameter() {
+		return this.parameter;
+	}
+
+
+	private static String getMethodParameterMessage(MethodParameter parameter) {
+		return "Could not resolve method parameter at index " + parameter.getParameterIndex() +
+				" in " + parameter.getMethod().toGenericString();
+	}
+
+}

spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/DefaultMessageHandlerMethodFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -41,6 +41,7 @@ import org.springframework.messaging.converter.MessageConverter;
 import org.springframework.messaging.handler.annotation.Payload;
 import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
+import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.validation.Errors;
@@ -53,13 +54,14 @@ import static org.junit.Assert.*;
  */
 public class DefaultMessageHandlerMethodFactoryTests {
 
+	private final SampleBean sample = new SampleBean();
+
 	@Rule
 	public final TestName name = new TestName();
 
 	@Rule
 	public final ExpectedException thrown = ExpectedException.none();
 
-	private final SampleBean sample = new SampleBean();
 
 	@Test
 	public void customConversion() throws Exception {
@@ -146,7 +148,7 @@ public class DefaultMessageHandlerMethodFactoryTests {
 		InvocableHandlerMethod invocableHandlerMethod2 =
 				createInvocableHandlerMethod(instance, "simpleString", String.class);
 
-		thrown.expect(IllegalStateException.class);
+		thrown.expect(MethodArgumentResolutionException.class);
 		thrown.expectMessage("No suitable resolver for");
 		invocableHandlerMethod2.invoke(message);
 	}
@@ -240,4 +242,5 @@ public class DefaultMessageHandlerMethodFactoryTests {
 			return Locale.getDefault();
 		}
 	}
+
 }

spring-web-reactive/src/main/java/org/springframework/web/reactive/result/method/InvocableHandlerMethod.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -45,6 +45,7 @@ import org.springframework.web.server.ServerWebExchange;
  * a {@link ServerWebExchange} and use that to invoke the underlying method.
  *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  * @since 5.0
  */
 public class InvocableHandlerMethod extends HandlerMethod {
@@ -89,14 +90,13 @@ public class InvocableHandlerMethod extends HandlerMethod {
 
 	/**
 	 * Invoke the method for the given exchange.
-	 *
 	 * @param exchange the current exchange
 	 * @param bindingContext the binding context to use
 	 * @param providedArgs optional list of argument values to match by type
 	 * @return Mono with a {@link HandlerResult}.
 	 */
-	public Mono<HandlerResult> invoke(ServerWebExchange exchange,
-			BindingContext bindingContext, Object... providedArgs) {
+	public Mono<HandlerResult> invoke(ServerWebExchange exchange, BindingContext bindingContext,
+			Object... providedArgs) {
 
 		return resolveArguments(exchange, bindingContext, providedArgs).then(args -> {
 			try {
@@ -108,14 +108,13 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				return Mono.error(ex.getTargetException());
 			}
 			catch (Throwable ex) {
-				String msg = getInvocationErrorMessage(args);
-				return Mono.error(new IllegalStateException(msg));
+				return Mono.error(new IllegalStateException(getInvocationErrorMessage(args)));
 			}
 		});
 	}
 
-	private Mono<Object[]> resolveArguments(ServerWebExchange exchange,
-			BindingContext bindingContext, Object... providedArgs) {
+	private Mono<Object[]> resolveArguments(ServerWebExchange exchange, BindingContext bindingContext,
+			Object... providedArgs) {
 
 		if (ObjectUtils.isEmpty(getMethodParameters())) {
 			return EMPTY_ARGS;
@@ -125,7 +124,7 @@ public class InvocableHandlerMethod extends HandlerMethod {
 					.map(param -> {
 						param.initParameterNameDiscovery(this.parameterNameDiscoverer);
 						GenericTypeResolver.resolveParameterType(param, getBean().getClass());
-						return findProvidedArg(param, providedArgs)
+						return findProvidedArgument(param, providedArgs)
 								.map(Mono::just)
 								.orElseGet(() -> {
 									HandlerMethodArgumentResolver resolver = findResolver(param);
@@ -144,12 +143,12 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		}
 	}
 
-	private Optional<Object> findProvidedArg(MethodParameter param, Object... providedArgs) {
+	private Optional<Object> findProvidedArgument(MethodParameter parameter, Object... providedArgs) {
 		if (ObjectUtils.isEmpty(providedArgs)) {
 			return Optional.empty();
 		}
 		return Arrays.stream(providedArgs)
-				.filter(arg -> param.getParameterType().isInstance(arg))
+				.filter(arg -> parameter.getParameterType().isInstance(arg))
 				.findFirst();
 	}
 
@@ -157,34 +156,33 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		return this.resolvers.stream()
 				.filter(r -> r.supportsParameter(param))
 				.findFirst()
-				.orElseThrow(() -> getArgumentError("No resolver for ", param, null));
+				.orElseThrow(() -> getArgumentError("No suitable resolver for", param, null));
 	}
 
-	private Mono<Object> resolveArg(HandlerMethodArgumentResolver resolver, MethodParameter param,
+	private Mono<Object> resolveArg(HandlerMethodArgumentResolver resolver, MethodParameter parameter,
 			BindingContext bindingContext, ServerWebExchange exchange) {
 
 		try {
-			return resolver.resolveArgument(param, bindingContext, exchange)
+			return resolver.resolveArgument(parameter, bindingContext, exchange)
 					.defaultIfEmpty(NO_ARG_VALUE)
 					.doOnError(cause -> {
 						if(logger.isDebugEnabled()) {
-							logger.debug(getDetailedErrorMessage("Error resolving ", param), cause);
+							logger.debug(getDetailedErrorMessage("Failed to resolve", parameter), cause);
 						}
 					});
 		}
 		catch (Exception ex) {
-			throw getArgumentError("Error resolving ", param, ex);
+			throw getArgumentError("Failed to resolve", parameter, ex);
 		}
 	}
 
-	private IllegalStateException getArgumentError(String message, MethodParameter param, Throwable ex) {
-		return new IllegalStateException(getDetailedErrorMessage(message, param), ex);
+	private IllegalStateException getArgumentError(String text, MethodParameter parameter, Throwable ex) {
+		return new IllegalStateException(getDetailedErrorMessage(text, parameter), ex);
 	}
 
-	private String getDetailedErrorMessage(String message, MethodParameter param) {
-		return message + "argument [" + param.getParameterIndex() + "] " +
-				"of type [" + param.getParameterType().getName() + "] " +
-				"on method [" + getBridgedMethod().toGenericString() + "]";
+	private String getDetailedErrorMessage(String text, MethodParameter param) {
+		return text + " argument " + param.getParameterIndex() + " of type '" +
+				param.getParameterType().getName() + "' on " + getBridgedMethod().toGenericString();
 	}
 
 	private Object doInvoke(Object[] args) throws Exception {
@@ -207,8 +205,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 						"[" + i + "][type=" + args[i].getClass().getName() + "][value=" + args[i] + "]" :
 						"[" + i + "][null]"))
 				.collect(Collectors.joining(",", " ", " "));
-		return "Failed to invoke controller with resolved arguments:" + argumentDetails +
-				"on method [" + getBridgedMethod().toGenericString() + "]";
+		return "Failed to invoke handler method with resolved arguments:" + argumentDetails +
+				"on " + getBridgedMethod().toGenericString();
 	}
 
 }

spring-web-reactive/src/test/java/org/springframework/web/reactive/result/method/InvocableHandlerMethodTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -34,18 +34,16 @@ import org.springframework.web.server.UnsupportedMediaTypeStatusException;
 import org.springframework.web.server.adapter.DefaultServerWebExchange;
 import org.springframework.web.server.session.MockWebSessionManager;
 
-import static org.hamcrest.Matchers.instanceOf;
-import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.assertTrue;
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
 import static org.mockito.Mockito.any;
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.*;
 
 /**
  * Unit tests for {@link InvocableHandlerMethod}.
+ *
  * @author Rossen Stoyanchev
+ * @author Juergen Hoeller
  */
 @SuppressWarnings("ThrowableResultOfMethodCallIgnored")
 public class InvocableHandlerMethodTests {
@@ -93,14 +91,14 @@ public class InvocableHandlerMethodTests {
 		InvocableHandlerMethod hm = handlerMethod("singleArg");
 		Mono<HandlerResult> mono = hm.invoke(this.exchange, new BindingContext());
 
-		StepVerifier.create(mono)
-				.expectNextCount(0)
-				.consumeErrorWith(error -> {
-					assertThat(error, instanceOf(IllegalStateException.class));
-					assertThat(error.getMessage(), is("No resolver for argument [0] of type [java.lang.String] " +
-							"on method [" + hm.getMethod().toGenericString() + "]"));
-				})
-				.verify();
+		try {
+			mono.block();
+			fail("Expected IllegalStateException");
+		}
+		catch (IllegalStateException ex) {
+			assertThat(ex.getMessage(), is("No suitable resolver for argument 0 of type 'java.lang.String' " +
+					"on " + hm.getMethod().toGenericString()));
+		}
 	}
 
 	@Test
@@ -109,13 +107,13 @@ public class InvocableHandlerMethodTests {
 		addResolver(hm, Mono.error(new UnsupportedMediaTypeStatusException("boo")));
 		Mono<HandlerResult> mono = hm.invoke(this.exchange, new BindingContext());
 
-		StepVerifier.create(mono)
-				.expectNextCount(0)
-				.consumeErrorWith(error -> {
-					assertThat(error, instanceOf(UnsupportedMediaTypeStatusException.class));
-					assertThat(error.getMessage(), is("Request failure [status: 415, reason: \"boo\"]"));
-				})
-				.verify();
+		try {
+			mono.block();
+			fail("Expected UnsupportedMediaTypeStatusException");
+		}
+		catch (UnsupportedMediaTypeStatusException ex) {
+			assertThat(ex.getMessage(), is("Request failure [status: 415, reason: \"boo\"]"));
+		}
 	}
 
 	@Test
@@ -124,15 +122,15 @@ public class InvocableHandlerMethodTests {
 		addResolver(hm, Mono.just(1));
 		Mono<HandlerResult> mono = hm.invoke(this.exchange, new BindingContext());
 
-		StepVerifier.create(mono)
-				.expectNextCount(0)
-				.consumeErrorWith(error -> {
-					assertThat(error, instanceOf(IllegalStateException.class));
-					assertThat(error.getMessage(), is("Failed to invoke controller with resolved arguments: " +
-							"[0][type=java.lang.Integer][value=1] " +
-							"on method [" + hm.getMethod().toGenericString() + "]"));
-				})
-				.verify();
+		try {
+			mono.block();
+			fail("Expected IllegalStateException");
+		}
+		catch (IllegalStateException ex) {
+			assertThat(ex.getMessage(), is("Failed to invoke handler method with resolved arguments: " +
+					"[0][type=java.lang.Integer][value=1] " +
+					"on " + hm.getMethod().toGenericString()));
+		}
 	}
 
 	@Test
@@ -140,13 +138,13 @@ public class InvocableHandlerMethodTests {
 		InvocableHandlerMethod hm = handlerMethod("exceptionMethod");
 		Mono<HandlerResult> mono = hm.invoke(this.exchange, new BindingContext());
 
-		StepVerifier.create(mono)
-				.expectNextCount(0)
-				.consumeErrorWith(error -> {
-					assertThat(error, instanceOf(IllegalStateException.class));
-					assertThat(error.getMessage(), is("boo"));
-				})
-				.verify();
+		try {
+			mono.block();
+			fail("Expected IllegalStateException");
+		}
+		catch (IllegalStateException ex) {
+			assertThat(ex.getMessage(), is("boo"));
+		}
 	}
 
 

spring-web/src/main/java/org/springframework/web/method/support/InvocableHandlerMethod.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -163,36 +163,23 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				}
 				catch (Exception ex) {
 					if (logger.isDebugEnabled()) {
-						logger.debug(getArgumentResolutionErrorMessage("Error resolving argument", i), ex);
+						logger.debug(getArgumentResolutionErrorMessage("Failed to resolve", i), ex);
 					}
 					throw ex;
 				}
 			}
 			if (args[i] == null) {
-				String msg = getArgumentResolutionErrorMessage("No suitable resolver for argument", i);
-				throw new IllegalStateException(msg);
+				throw new IllegalStateException("Could not resolve method parameter at index " +
+						parameter.getParameterIndex() + " in " + parameter.getMethod().toGenericString() +
+						": " + getArgumentResolutionErrorMessage("No suitable resolver for", i));
 			}
 		}
 		return args;
 	}
 
-	private String getArgumentResolutionErrorMessage(String message, int index) {
-		MethodParameter param = getMethodParameters()[index];
-		message += " [" + index + "] [type=" + param.getParameterType().getName() + "]";
-		return getDetailedErrorMessage(message);
-	}
-
-	/**
-	 * Adds HandlerMethod details such as the controller type and method
-	 * signature to the given error message.
-	 * @param message error message to append the HandlerMethod details to
-	 */
-	protected String getDetailedErrorMessage(String message) {
-		StringBuilder sb = new StringBuilder(message).append("\n");
-		sb.append("HandlerMethod details: \n");
-		sb.append("Controller [").append(getBeanType().getName()).append("]\n");
-		sb.append("Method [").append(getBridgedMethod().toGenericString()).append("]\n");
-		return sb.toString();
+	private String getArgumentResolutionErrorMessage(String text, int index) {
+		Class<?> paramType = getMethodParameters()[index].getParameterType();
+		return text + " argument " + index + " of type '" + paramType.getName() + "'";
 	}
 
 	/**
@@ -221,8 +208,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		}
 		catch (IllegalArgumentException ex) {
 			assertTargetBean(getBridgedMethod(), getBean(), args);
-			String message = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
-			throw new IllegalStateException(getInvocationErrorMessage(message, args), ex);
+			String text = (ex.getMessage() != null ? ex.getMessage() : "Illegal argument");
+			throw new IllegalStateException(getInvocationErrorMessage(text, args), ex);
 		}
 		catch (InvocationTargetException ex) {
 			// Unwrap for HandlerExceptionResolvers ...
@@ -237,8 +224,8 @@ public class InvocableHandlerMethod extends HandlerMethod {
 				throw (Exception) targetException;
 			}
 			else {
-				String msg = getInvocationErrorMessage("Failed to invoke controller method", args);
-				throw new IllegalStateException(msg, targetException);
+				String text = getInvocationErrorMessage("Failed to invoke handler method", args);
+				throw new IllegalStateException(text, targetException);
 			}
 		}
 	}
@@ -254,16 +241,16 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		Class<?> methodDeclaringClass = method.getDeclaringClass();
 		Class<?> targetBeanClass = targetBean.getClass();
 		if (!methodDeclaringClass.isAssignableFrom(targetBeanClass)) {
-			String msg = "The mapped controller method class '" + methodDeclaringClass.getName() +
+			String text = "The mapped handler method class '" + methodDeclaringClass.getName() +
 					"' is not an instance of the actual controller bean class '" +
 					targetBeanClass.getName() + "'. If the controller requires proxying " +
 					"(e.g. due to @Transactional), please use class-based proxying.";
-			throw new IllegalStateException(getInvocationErrorMessage(msg, args));
+			throw new IllegalStateException(getInvocationErrorMessage(text, args));
 		}
 	}
 
-	private String getInvocationErrorMessage(String message, Object[] resolvedArgs) {
-		StringBuilder sb = new StringBuilder(getDetailedErrorMessage(message));
+	private String getInvocationErrorMessage(String text, Object[] resolvedArgs) {
+		StringBuilder sb = new StringBuilder(getDetailedErrorMessage(text));
 		sb.append("Resolved arguments: \n");
 		for (int i = 0; i < resolvedArgs.length; i++) {
 			sb.append("[").append(i).append("] ");
@@ -278,4 +265,16 @@ public class InvocableHandlerMethod extends HandlerMethod {
 		return sb.toString();
 	}
 
+	/**
+	 * Adds HandlerMethod details such as the bean type and method signature to the message.
+	 * @param text error message to append the HandlerMethod details to
+	 */
+	protected String getDetailedErrorMessage(String text) {
+		StringBuilder sb = new StringBuilder(text).append("\n");
+		sb.append("HandlerMethod details: \n");
+		sb.append("Controller [").append(getBeanType().getName()).append("]\n");
+		sb.append("Method [").append(getBridgedMethod().toGenericString()).append("]\n");
+		return sb.toString();
+	}
+
 }

spring-web/src/test/java/org/springframework/web/method/support/InvocableHandlerMethodTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -93,7 +93,7 @@ public class InvocableHandlerMethodTests {
 			fail("Expected exception");
 		}
 		catch (IllegalStateException ex) {
-			assertTrue(ex.getMessage().contains("No suitable resolver for argument [0] [type=java.lang.Integer]"));
+			assertTrue(ex.getMessage().contains("No suitable resolver for argument 0 of type 'java.lang.Integer'"));
 		}
 	}
 
@@ -192,7 +192,7 @@ public class InvocableHandlerMethodTests {
 		catch (IllegalStateException actual) {
 			assertNotNull(actual.getCause());
 			assertSame(expected, actual.getCause());
-			assertTrue(actual.getMessage().contains("Failed to invoke controller method"));
+			assertTrue(actual.getMessage().contains("Failed to invoke handler method"));
 		}
 	}