/*
* Copyright (c) 2007 Mockito contributors
* This program is made available under the terms of the MIT License.
*/
package org.mockito.internal.stubbing.defaultanswers;
import java.io.Serializable;
import java.lang.reflect.Modifier;
import org.mockito.Mockito;
import org.mockito.exceptions.Reporter;
import org.mockito.internal.debugging.LocationImpl;
import org.mockito.invocation.Location;
import org.mockito.internal.util.ObjectMethodsGuru;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
/**
* Optional Answer that can be used with
* {@link Mockito#mock(Class, Answer)}
* <p>
* This implementation can be helpful when working with legacy code. Unstubbed
* methods often return null. If your code uses the object returned by an
* unstubbed call you get a NullPointerException. This implementation of
* Answer returns SmartNulls instead of nulls.
* SmartNull gives nicer exception message than NPE because it points out the
* line where unstubbed method was called. You just click on the stack trace.
* <p>
* ReturnsSmartNulls first tries to return ordinary return values (see
* {@link ReturnsMoreEmptyValues}) then it tries to return SmartNull. If the
* return type is not mockable (e.g. final) then ordinary null is returned.
* <p>
* ReturnsSmartNulls will be probably the default return values strategy in
* Mockito 2.0
*/
public class ReturnsSmartNulls implements Answer<Object>, Serializable {
private static final long serialVersionUID = 7618312406617949441L;
private final Answer<Object> delegate = new ReturnsMoreEmptyValues();
public Object answer(final InvocationOnMock invocation) throws Throwable {
Object defaultReturnValue = delegate.answer(invocation);
if (defaultReturnValue != null) {
return defaultReturnValue;
}
Class<?> type = invocation.getMethod().getReturnType();
if (!type.isPrimitive() && !Modifier.isFinal(type.getModifiers())) {
final Location location = new LocationImpl();
return Mockito.mock(type, new ThrowsSmartNullPointer(invocation, location));
}
return null;
}
private static class ThrowsSmartNullPointer implements Answer {
private final InvocationOnMock unstubbedInvocation;
private final Location location;
public ThrowsSmartNullPointer(InvocationOnMock unstubbedInvocation, Location location) {
this.unstubbedInvocation = unstubbedInvocation;
this.location = location;
}
public Object answer(InvocationOnMock currentInvocation) throws Throwable {
if (new ObjectMethodsGuru().isToString(currentInvocation.getMethod())) {
return "SmartNull returned by this unstubbed method call on a mock:\n" +
unstubbedInvocation.toString();
}
new Reporter().smartNullPointerException(unstubbedInvocation.toString(), location);
return null;
}
}
}