src/org/mockito/internal/stubbing/defaultanswers/ReturnsDeepStubs.java

/*
 * Copyright (c) 2007 Mockito contributors
 * This program is made available under the terms of the MIT License.
 */
package org.mockito.internal.stubbing.defaultanswers;

import org.mockito.MockSettings;
import org.mockito.internal.InternalMockHandler;
import org.mockito.internal.MockitoCore;
import org.mockito.internal.creation.settings.CreationSettings;
import org.mockito.internal.stubbing.InvocationContainerImpl;
import org.mockito.internal.stubbing.StubbedInvocationMatcher;
import org.mockito.internal.util.MockUtil;
import org.mockito.internal.util.reflection.GenericMetadataSupport;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

import java.io.Serializable;

import static org.mockito.Mockito.withSettings;

/**
 * Returning deep stub implementation.
 *
 * Will return previously created mock if the invocation matches.
 *
 * <p>Supports nested generic information, with this answer you can write code like this :
 *
 * <pre class="code"><code class="java">
 *     interface GenericsNest&lt;K extends Comparable&lt;K&gt; & Cloneable&gt; extends Map&lt;K, Set&lt;Number&gt;&gt; {}
 *
 *     GenericsNest&lt;?&gt; mock = mock(GenericsNest.class, new ReturnsGenericDeepStubs());
 *     Number number = mock.entrySet().iterator().next().getValue().iterator().next();
 * </code></pre>
 * </p>
 *
 * @see org.mockito.Mockito#RETURNS_DEEP_STUBS
 * @see org.mockito.Answers#RETURNS_DEEP_STUBS
 */
public class ReturnsDeepStubs implements Answer<Object>, Serializable {
    
    private static final long serialVersionUID = -7105341425736035847L;

    private MockitoCore mockitoCore = new MockitoCore();
    private ReturnsEmptyValues delegate = new ReturnsEmptyValues();

    public Object answer(InvocationOnMock invocation) throws Throwable {
        GenericMetadataSupport returnTypeGenericMetadata =
                actualParameterizedType(invocation.getMock()).resolveGenericReturnType(invocation.getMethod());

        Class<?> rawType = returnTypeGenericMetadata.rawType();
        if (!mockitoCore.isTypeMockable(rawType)) {
            return delegate.returnValueFor(rawType);
        }

        return getMock(invocation, returnTypeGenericMetadata);
    }

    private Object getMock(InvocationOnMock invocation, GenericMetadataSupport returnTypeGenericMetadata) throws Throwable {
    	InternalMockHandler<Object> handler = new MockUtil().getMockHandler(invocation.getMock());
    	InvocationContainerImpl container = (InvocationContainerImpl) handler.getInvocationContainer();

        // matches invocation for verification
        for (StubbedInvocationMatcher stubbedInvocationMatcher : container.getStubbedInvocations()) {
    		if(container.getInvocationForStubbing().matches(stubbedInvocationMatcher.getInvocation())) {
    			return stubbedInvocationMatcher.answer(invocation);
    		}
		}

        // deep stub
        return recordDeepStubMock(createNewDeepStubMock(returnTypeGenericMetadata), container);
    }

    /**
     * Creates a mock using the Generics Metadata.
     *
     * <li>Finally as we want to mock the actual type, but we want to pass along the contextual generics meta-data
     * that was resolved for the current return type, for this to happen we associate to the mock an new instance of
     * {@link ReturnsDeepStubs} answer in which we will store the returned type generic metadata.
     *
     * @param returnTypeGenericMetadata The metadata to use to create the new mock.
     * @return The mock
     */
    private Object createNewDeepStubMock(GenericMetadataSupport returnTypeGenericMetadata) {
        return mockitoCore.mock(
                returnTypeGenericMetadata.rawType(),
                withSettingsUsing(returnTypeGenericMetadata)
        );
    }

    private MockSettings withSettingsUsing(GenericMetadataSupport returnTypeGenericMetadata) {
        MockSettings mockSettings =
                returnTypeGenericMetadata.rawExtraInterfaces().length > 0 ?
                withSettings().extraInterfaces(returnTypeGenericMetadata.rawExtraInterfaces())
                : withSettings();

        return mockSettings
                .defaultAnswer(returnsDeepStubsAnswerUsing(returnTypeGenericMetadata));
    }

    private ReturnsDeepStubs returnsDeepStubsAnswerUsing(final GenericMetadataSupport returnTypeGenericMetadata) {
        return new ReturnsDeepStubs() {
            @Override
            protected GenericMetadataSupport actualParameterizedType(Object mock) {
                return returnTypeGenericMetadata;
            }
        };
    }

    private Object recordDeepStubMock(final Object mock, InvocationContainerImpl container) throws Throwable {

        container.addAnswer(new Answer<Object>() {
            public Object answer(InvocationOnMock invocation) throws Throwable {
                return mock;
            }
        }, false);

        return mock;
    }

    protected GenericMetadataSupport actualParameterizedType(Object mock) {
        CreationSettings mockSettings = (CreationSettings) new MockUtil().getMockHandler(mock).getMockSettings();
        return GenericMetadataSupport.inferFrom(mockSettings.getTypeToMock());
    }
}