Backported further GenericTypeResolver tests

Issue: SPR-11052

spring-core/src/main/java/org/springframework/core/GenericTypeResolver.java

@@ -231,7 +231,7 @@ public abstract class GenericTypeResolver {
 	 * @return the resolved type of the argument, or {@code null} if not resolvable
 	 */
 	public static Class<?> resolveTypeArgument(Class<?> clazz, Class<?> genericIfc) {
-		Class[] typeArgs = resolveTypeArguments(clazz, genericIfc);
+		Class<?>[] typeArgs = resolveTypeArguments(clazz, genericIfc);
 		if (typeArgs == null) {
 			return null;
 		}
@@ -246,21 +246,25 @@ public abstract class GenericTypeResolver {
 	 * Resolve the type arguments of the given generic interface against the given
 	 * target class which is assumed to implement the generic interface and possibly
 	 * declare concrete types for its type variables.
+	 * <p>Note: In Spring 3.2, this method doesn't return {@code null} in all scenarios
+	 * where it should. To be fixed in Spring 4.0; for client code, this just means it
+	 * might see {@code null} in a few more cases then where it now sees an array with
+	 * a single {@link Object} type.
 	 * @param clazz the target class to check against
 	 * @param genericIfc the generic interface or superclass to resolve the type argument from
 	 * @return the resolved type of each argument, with the array size matching the
 	 * number of actual type arguments, or {@code null} if not resolvable
 	 */
-	public static Class[] resolveTypeArguments(Class<?> clazz, Class<?> genericIfc) {
+	public static Class<?>[] resolveTypeArguments(Class<?> clazz, Class<?> genericIfc) {
 		return doResolveTypeArguments(clazz, clazz, genericIfc);
 	}
 
-	private static Class[] doResolveTypeArguments(Class<?> ownerClass, Class<?> classToIntrospect, Class<?> genericIfc) {
+	private static Class<?>[] doResolveTypeArguments(Class<?> ownerClass, Class<?> classToIntrospect, Class<?> genericIfc) {
 		while (classToIntrospect != null) {
 			if (genericIfc.isInterface()) {
 				Type[] ifcs = classToIntrospect.getGenericInterfaces();
 				for (Type ifc : ifcs) {
-					Class[] result = doResolveTypeArguments(ownerClass, ifc, genericIfc);
+					Class<?>[] result = doResolveTypeArguments(ownerClass, ifc, genericIfc);
 					if (result != null) {
 						return result;
 					}
@@ -268,7 +272,7 @@ public abstract class GenericTypeResolver {
 			}
 			else {
 				try {
-					Class[] result = doResolveTypeArguments(ownerClass, classToIntrospect.getGenericSuperclass(), genericIfc);
+					Class<?>[] result = doResolveTypeArguments(ownerClass, classToIntrospect.getGenericSuperclass(), genericIfc);
 					if (result != null) {
 						return result;
 					}
@@ -283,13 +287,13 @@ public abstract class GenericTypeResolver {
 		return null;
 	}
 
-	private static Class[] doResolveTypeArguments(Class<?> ownerClass, Type ifc, Class<?> genericIfc) {
+	private static Class<?>[] doResolveTypeArguments(Class<?> ownerClass, Type ifc, Class<?> genericIfc) {
 		if (ifc instanceof ParameterizedType) {
 			ParameterizedType paramIfc = (ParameterizedType) ifc;
 			Type rawType = paramIfc.getRawType();
 			if (genericIfc.equals(rawType)) {
 				Type[] typeArgs = paramIfc.getActualTypeArguments();
-				Class[] result = new Class[typeArgs.length];
+				Class<?>[] result = new Class[typeArgs.length];
 				for (int i = 0; i < typeArgs.length; i++) {
 					Type arg = typeArgs[i];
 					result[i] = extractClass(ownerClass, arg);

spring-core/src/test/java/org/springframework/core/GenericTypeResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 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.
@@ -21,10 +21,12 @@ import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.junit.Test;
 
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 import static org.springframework.core.GenericTypeResolver.*;
 import static org.springframework.util.ReflectionUtils.*;
@@ -63,28 +65,33 @@ public class GenericTypeResolverTests {
 
 	@Test
 	public void methodReturnTypes() {
-		assertEquals(Integer.class, resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "integer"), MyInterfaceType.class));
-		assertEquals(String.class, resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "string"), MyInterfaceType.class));
+		assertEquals(Integer.class,
+				resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "integer"), MyInterfaceType.class));
+		assertEquals(String.class,
+				resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "string"), MyInterfaceType.class));
 		assertEquals(null, resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "raw"), MyInterfaceType.class));
-		assertEquals(null, resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "object"), MyInterfaceType.class));
+		assertEquals(null,
+				resolveReturnTypeArgument(findMethod(MyTypeWithMethods.class, "object"), MyInterfaceType.class));
 	}
 
 	@Test
 	public void testResolveType() {
-			Method intMessageMethod = findMethod(MyTypeWithMethods.class, "readIntegerInputMessage", MyInterfaceType.class);
-			MethodParameter intMessageMethodParam = new MethodParameter(intMessageMethod, 0);
-			assertEquals(MyInterfaceType.class,
-							resolveType(intMessageMethodParam.getGenericParameterType(), new HashMap<TypeVariable, Type>()));
-
-			Method intArrMessageMethod = findMethod(MyTypeWithMethods.class, "readIntegerArrayInputMessage", MyInterfaceType[].class);
-			MethodParameter intArrMessageMethodParam = new MethodParameter(intArrMessageMethod, 0);
-			assertEquals(MyInterfaceType[].class,
-							resolveType(intArrMessageMethodParam.getGenericParameterType(), new HashMap<TypeVariable, Type>()));
-
-			Method genericArrMessageMethod = findMethod(MySimpleTypeWithMethods.class, "readGenericArrayInputMessage", Object[].class);
-			MethodParameter genericArrMessageMethodParam = new MethodParameter(genericArrMessageMethod, 0);
-			Map<TypeVariable, Type> varMap = getTypeVariableMap(MySimpleTypeWithMethods.class);
-			assertEquals(Integer[].class, resolveType(genericArrMessageMethodParam.getGenericParameterType(), varMap));
+		Method intMessageMethod = findMethod(MyTypeWithMethods.class, "readIntegerInputMessage", MyInterfaceType.class);
+		MethodParameter intMessageMethodParam = new MethodParameter(intMessageMethod, 0);
+		assertEquals(MyInterfaceType.class,
+				resolveType(intMessageMethodParam.getGenericParameterType(), new HashMap<TypeVariable, Type>()));
+
+		Method intArrMessageMethod = findMethod(MyTypeWithMethods.class, "readIntegerArrayInputMessage",
+				MyInterfaceType[].class);
+		MethodParameter intArrMessageMethodParam = new MethodParameter(intArrMessageMethod, 0);
+		assertEquals(MyInterfaceType[].class,
+				resolveType(intArrMessageMethodParam.getGenericParameterType(), new HashMap<TypeVariable, Type>()));
+
+		Method genericArrMessageMethod = findMethod(MySimpleTypeWithMethods.class, "readGenericArrayInputMessage",
+				Object[].class);
+		MethodParameter genericArrMessageMethodParam = new MethodParameter(genericArrMessageMethod, 0);
+		Map<TypeVariable, Type> varMap = getTypeVariableMap(MySimpleTypeWithMethods.class);
+		assertEquals(Integer[].class, resolveType(genericArrMessageMethodParam.getGenericParameterType(), varMap));
 	}
 
 	@Test
@@ -92,7 +99,76 @@ public class GenericTypeResolverTests {
 		assertEquals(B.class, resolveTypeArgument(TestImpl.class, ITest.class));
 	}
 
+	@Test
+	public void testGetTypeVariableMap() throws Exception {
+		Map<TypeVariable, Type> map;
+
+		map = GenericTypeResolver.getTypeVariableMap(MySimpleInterfaceType.class);
+		assertThat(map.toString(), equalTo("{T=class java.lang.String}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(MyCollectionInterfaceType.class);
+		assertThat(map.toString(), equalTo("{T=java.util.Collection<java.lang.String>}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(MyCollectionSuperclassType.class);
+		assertThat(map.toString(), equalTo("{T=java.util.Collection<java.lang.String>}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(MySimpleTypeWithMethods.class);
+		assertThat(map.toString(), equalTo("{T=class java.lang.Integer}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(TopLevelClass.class);
+		assertThat(map.toString(), equalTo("{}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(TypedTopLevelClass.class);
+		assertThat(map.toString(), equalTo("{T=class java.lang.Integer}"));
+
+		map = GenericTypeResolver.getTypeVariableMap(TypedTopLevelClass.TypedNested.class);
+		assertThat(map.size(), equalTo(2));
+		Type t = null;
+		Type x = null;
+		for (Map.Entry<TypeVariable, Type> entry : map.entrySet()) {
+			if(entry.getKey().toString().equals("T")) {
+				t = entry.getValue();
+			}
+			else {
+				x = entry.getValue();
+			}
+		}
+		assertThat(t, equalTo((Type) Integer.class));
+		assertThat(x, equalTo((Type) Long.class));
+	}
+
+	@Test
+	public void getGenericsCannotBeResolved() throws Exception {
+		// SPR-11030
+		Class<?>[] resolved = GenericTypeResolver.resolveTypeArguments(List.class, Iterable.class);
+		// Note: to be changed to return null in Spring 4.0
+		assertThat(resolved, equalTo(new Class[] {Object.class}));
+	}
 
+	@Test
+	public void getRawMapTypeCannotBeResolved() throws Exception {
+		// SPR-11052
+		Class<?>[] resolved = GenericTypeResolver.resolveTypeArguments(Map.class, Map.class);
+		assertNull(resolved);
+	}
+
+	@Test
+	public void getGenericsOnArrayFromParamCannotBeResolved() throws Exception {
+		// SPR-11044
+		MethodParameter methodParameter = MethodParameter.forMethodOrConstructor(
+				WithArrayBase.class.getDeclaredMethod("array", Object[].class), 0);
+		Class<?> resolved = GenericTypeResolver.resolveParameterType(methodParameter, WithArray.class);
+		assertThat(resolved, equalTo((Class) Object[].class));
+	}
+
+	@Test
+	public void getGenericsOnArrayFromReturnCannotBeResolved() throws Exception {
+		// SPR-11044
+		Class<?> resolved = GenericTypeResolver.resolveReturnType(
+				WithArrayBase.class.getDeclaredMethod("array", Object[].class),
+				WithArray.class);
+		assertThat(resolved, equalTo((Class) Object[].class));
+	}
 
 	public interface MyInterfaceType<T> {
 	}
@@ -113,26 +189,44 @@ public class GenericTypeResolverTests {
 	}
 
 	public static class MyTypeWithMethods<T> {
-		public MyInterfaceType<Integer> integer() { return null; }
-		public MySimpleInterfaceType string() { return null; }
-		public Object object() { return null; }
+
+		public MyInterfaceType<Integer> integer() {
+			return null;
+		}
+
+		public MySimpleInterfaceType string() {
+			return null;
+		}
+
+		public Object object() {
+			return null;
+		}
+
 		@SuppressWarnings("rawtypes")
-		public MyInterfaceType raw() { return null; }
-		public String notParameterized() { return null; }
-		public String notParameterizedWithArguments(Integer x, Boolean b) { return null; }
+		public MyInterfaceType raw() {
+			return null;
+		}
+
+		public String notParameterized() {
+			return null;
+		}
+
+		public String notParameterizedWithArguments(Integer x, Boolean b) {
+			return null;
+		}
 
 		/**
-		 * Simulates a factory method that wraps the supplied object in a proxy
-		 * of the same type.
+		 * Simulates a factory method that wraps the supplied object in a proxy of the
+		 * same type.
 		 */
 		public static <T> T createProxy(T object) {
 			return null;
 		}
 
 		/**
-		 * Similar to {@link #createProxy(Object)} but adds an additional argument
-		 * before the argument of type {@code T}. Note that they may potentially
-		 * be of the same time when invoked!
+		 * Similar to {@link #createProxy(Object)} but adds an additional argument before
+		 * the argument of type {@code T}. Note that they may potentially be of the same
+		 * time when invoked!
 		 */
 		public static <T> T createNamedProxy(String name, T object) {
 			return null;
@@ -146,8 +240,8 @@ public class GenericTypeResolverTests {
 		}
 
 		/**
-		 * Similar to {@link #createMock(Class)} but adds an additional method
-		 * argument before the parameterized argument.
+		 * Similar to {@link #createMock(Class)} but adds an additional method argument
+		 * before the parameterized argument.
 		 */
 		public static <T> T createNamedMock(String name, Class<T> toMock) {
 			return null;
@@ -162,8 +256,8 @@ public class GenericTypeResolverTests {
 		}
 
 		/**
-		 * Extract some value of the type supported by the interface (i.e., by
-		 * a concrete, non-generic implementation of the interface).
+		 * Extract some value of the type supported by the interface (i.e., by a concrete,
+		 * non-generic implementation of the interface).
 		 */
 		public static <T> T extractValueFrom(MyInterfaceType<T> myInterfaceType) {
 			return null;
@@ -201,4 +295,22 @@ public class GenericTypeResolverTests {
 	class TestImpl<I extends A, T extends B<I>> extends ITest<T>{
 	}
 
+	static class TopLevelClass<T> {
+		class Nested<X> {
+		}
+	}
+
+	static class TypedTopLevelClass extends TopLevelClass<Integer> {
+		class TypedNested extends Nested<Long> {
+		}
+	}
+
+	static abstract class WithArrayBase<T> {
+
+		public abstract T[] array(T... args);
+	}
+
+	static abstract class WithArray<T> extends WithArrayBase<T> {
+	}
+
 }