Compare Class#getInterfaces() with org.springframework.util.ClassUtils#getAllInterfaces()

GetAllInterfacesTest.java

import static org.junit.Assert.*;

import org.junit.Test;
import org.springframework.util.ClassUtils;

public class GetAllInterfacesTest {
	@Test
	public void getInterfaceTest() throws Exception {
		Class<?>[] interfaces = new ConcreteClass1().getClass().getInterfaces();
		assertEquals(0, interfaces.length);
	}

	@Test
	public void UseClassUtils() throws Exception {
		Class[] allInterfaces = ClassUtils.getAllInterfaces(new ConcreteClass1());
		assertEquals(Interface1.class, allInterfaces[0]);
	}

	@Test
	public void ParentsAndChildImplementsDifferentClass() throws Exception {
		Class[] allInterfaces = ClassUtils.getAllInterfaces(new ConcreteClass2());
		// child->parent
		assertEquals(Interface2.class, allInterfaces[0]);
		assertEquals(Interface3.class, allInterfaces[1]);
		assertEquals(Interface1.class, allInterfaces[2]);
		
		allInterfaces = ClassUtils.getAllInterfaces(new ConcreteClass3());
		// declare order
		assertEquals(Interface3.class, allInterfaces[0]);
		assertEquals(Interface2.class, allInterfaces[1]);
		assertEquals(Interface1.class, allInterfaces[2]);
	}

	@Test
	public void ParentsAndChildImplementsSameClass() throws Exception {
		Class[] allInterfaces = ClassUtils.getAllInterfaces(new ConcreteClass4());
		// exclude same class
		assertEquals(2, allInterfaces.length);
		assertEquals(Interface1.class, allInterfaces[0]);
		assertEquals(Interface2.class, allInterfaces[1]);
	}

	@Test
	public void VariableDeclarationIsInterface() throws Exception {
		Interface1 instance = new ConcreteClass4();
		Class[] allInterfaces = ClassUtils.getAllInterfaces(instance);
		assertEquals(2, allInterfaces.length);
		assertEquals(Interface1.class, allInterfaces[0]);
		assertEquals(Interface2.class, allInterfaces[1]);
	}

	@Test
	public void ThreeLayerClass() throws Exception {
		Class[] allInterfaces = ClassUtils.getAllInterfaces(new ConcreteClass5());
		assertEquals(3, allInterfaces.length);
		assertEquals(Interface3.class, allInterfaces[0]);
		assertEquals(Interface1.class, allInterfaces[1]);
		assertEquals(Interface2.class, allInterfaces[2]);
	}

	private static interface Interface1 {
	}
	private static interface Interface2 {
	}
	private static interface Interface3 {
	}

	private static abstract class AbstractClass implements Interface1 {
	}

	private static class ConcreteClass1 extends AbstractClass {
	}
	private static class ConcreteClass2 extends AbstractClass implements Interface2, Interface3 {
	}
	private static class ConcreteClass3 extends AbstractClass implements Interface3, Interface2 {
	}
	private static class ConcreteClass4 extends AbstractClass implements Interface1, Interface2 {
	}
	private static class ConcreteClass5 extends ConcreteClass4 implements Interface3 {
	}
}