Assert pre-conditions in AopTestUtils

Issue: SPR-13005

spring-test/src/test/java/org/springframework/test/util/AopTestUtilsTests.java

@@ -36,6 +36,11 @@ public class AopTestUtilsTests {
 	private final FooImpl foo = new FooImpl();
 
 
+	@Test(expected = IllegalArgumentException.class)
+	public void getTargetObjectForNull() {
+		getTargetObject(null);
+	}
+
 	@Test
 	public void getTargetObjectForNonProxiedObject() {
 		Foo target = getTargetObject(foo);
@@ -66,6 +71,11 @@ public class AopTestUtilsTests {
 		assertNotSame(foo, target);
 	}
 
+	@Test(expected = IllegalArgumentException.class)
+	public void getUltimateTargetObjectForNull() {
+		getUltimateTargetObject(null);
+	}
+
 	@Test
 	public void getUltimateTargetObjectForNonProxiedObject() {
 		Foo target = getUltimateTargetObject(foo);