MockSatisfaction.java

/*
 * Grapht, an open source dependency injector.
 * Copyright 2014-2015 various contributors (see CONTRIBUTORS.txt)
 * Copyright 2010-2014 Regents of the University of Minnesota
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
package org.grouplens.grapht.reflect;

import org.grouplens.grapht.*;

import javax.inject.Provider;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;


/**
 * MockSatisfaction is a simple implementation of Satisfactions for certain
 * types of test cases. It can be configured by its constructors, although
 * {@link Satisfaction#makeInstantiator(Map, LifecycleManager)} always returns the same provider.
 * 
 * @author <a href="http://grouplens.org">GroupLens Research</a>
 */
public class MockSatisfaction implements Satisfaction {
    private static final long serialVersionUID = 1L;

    private final Provider<?> provider;
    private final Class<?> type;
    private final List<Desire> dependencies;
    
    public MockSatisfaction() {
        this(Object.class, new Object(), new ArrayList<Desire>());
    }
    
    public MockSatisfaction(Class<?> type) {
        this(type, new ArrayList<Desire>());
    }
    
    public MockSatisfaction(Class<?> type, List<Desire> dependencies) {
        this(type, new NullProvider(), dependencies);
    }
    
    public MockSatisfaction(Class<?> type, Object instance, List<Desire> dependencies) {
        this(type, new InstanceProvider(instance), dependencies);
    }
    
    public MockSatisfaction(Class<?> type, Provider<?> provider, List<Desire> dependencies) {
        this.type = type;
        this.provider = provider;
        this.dependencies = dependencies;
    }
    
    @Override
    public CachePolicy getDefaultCachePolicy() {
        return CachePolicy.NO_PREFERENCE;
    }
    
    @Override
    public List<Desire> getDependencies() {
        return dependencies;
    }

    @Override
    public Type getType() {
        return type;
    }

    @Override
    public Class<?> getErasedType() {
        return type;
    }

    @Override
    public boolean hasInstance() {
        return true;
    }

    @Override
    public <T> T visit(SatisfactionVisitor<T> visitor) {
        throw new UnsupportedOperationException("cannot visit the mock satisfaction");
    }

    @Override
    public Instantiator makeInstantiator(Map<Desire,Instantiator> dependencies,
                                         LifecycleManager lm) {
        return Instantiators.ofProvider(provider);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        return sb.append("mock satisfaction of ")
                 .append(type)
                 .append(" with provider ")
                 .append(provider)
                 .append(" (")
                 .append(dependencies.size())
                 .append(" dependencies)")
                 .toString();
    }

    @SuppressWarnings("rawtypes")
    private static class NullProvider implements Provider {
        @Override
        public Object get() {
            return null;
        }

        @Override
        public String toString() {
            return "return null";
        }
    }
    
    @SuppressWarnings("rawtypes")
    private static class InstanceProvider implements Provider {
        private final Object instance;
        
        public InstanceProvider(Object instance) {
            this.instance = instance;
        }
        
        @Override
        public Object get() {
            return instance;
        }

        @Override
        public String toString() {
            return "return " + instance;
        }
    }
}