DATACMNS-769 - Fixed assignability check for from QueryMethod.

The assignability check of method return types now explicitly detects wrapper types supported in QueryExceutionConverters and automatically unwraps those before the actual check.

Author: odrotbohm

src/main/java/org/springframework/data/repository/util/ClassUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2013 the original author or authors.
+ * Copyright 2008-2015 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.
@@ -21,6 +21,9 @@
 import java.util.Collection;
 
 import org.springframework.data.repository.Repository;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
+import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
@@ -34,9 +37,7 @@ public abstract class ClassUtils {
 	/**
 	 * Private constructor to prevent instantiation.
 	 */
-	private ClassUtils() {
-
-	}
+	private ClassUtils() {}
 
 	/**
 	 * Returns whether the given class contains a property with the given name.
@@ -96,15 +97,22 @@ public static int getNumberOfOccurences(Method method, Class<?> type) {
 	}
 
 	/**
-	 * Asserts the given {@link Method}'s return type to be one of the given types.
+	 * Asserts the given {@link Method}'s return type to be one of the given types. Will unwrap known wrapper types before
+	 * the assignment check (see {@link QueryExecutionConverters}).
 	 * 
-	 * @param method
-	 * @param types
+	 * @param method must not be {@literal null}.
+	 * @param types must not be {@literal null} or empty.
 	 */
 	public static void assertReturnTypeAssignable(Method method, Class<?>... types) {
 
+		Assert.notNull(method, "Method must not be null!");
+		Assert.notEmpty(types, "Types must not be null or empty!");
+
+		TypeInformation<?> returnType = ClassTypeInformation.fromReturnTypeOf(method);
+		returnType = QueryExecutionConverters.supports(returnType.getType()) ? returnType.getComponentType() : returnType;
+
 		for (Class<?> type : types) {
-			if (type.isAssignableFrom(method.getReturnType())) {
+			if (type.isAssignableFrom(returnType.getType())) {
 				return;
 			}
 		}

src/test/java/org/springframework/data/repository/util/ClassUtilsUnitTests.java

@@ -19,13 +19,16 @@
 import static org.springframework.data.repository.util.ClassUtils.*;
 
 import java.io.Serializable;
+import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.Future;
 
 import org.junit.Test;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.repository.Repository;
+import org.springframework.scheduling.annotation.Async;
 
 /**
  * Unit test for {@link ClassUtils}.
@@ -48,6 +51,17 @@ public void determinesValidFieldsCorrectly() {
 		assertFalse(hasProperty(User.class, "address"));
 	}
 
+	/**
+	 * @see DATACMNS-769
+	 */
+	@Test
+	public void unwrapsWrapperTypesBeforeAssignmentCheck() throws Exception {
+
+		Method method = UserRepository.class.getMethod("findAsync", Pageable.class);
+
+		assertReturnTypeAssignable(method, Page.class);
+	}
+
 	@SuppressWarnings("unused")
 	private class User {
 
@@ -61,6 +75,8 @@ public String getAddress() {
 
 	static interface UserRepository extends Repository<User, Integer> {
 
+		@Async
+		Future<Page<User>> findAsync(Pageable pageable);
 	}
 
 	interface SomeDao extends Serializable, UserRepository {