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/*
 * GroupLens Common Utilities
 * Copyright © 2011 Regents of the University of Minnesota
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the
 *    distribution.
 *
 *  * Neither the name of the University of Minnesota nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software has been partly funded by NSF grant IIS 08-08692.
 */
package org.grouplens.common.test;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.FrameworkMethod;
import org.junit.runners.model.InitializationError;
import org.junit.runners.model.Statement;

import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Module;

/**
 * 
 * GuiceTestRunner allows junit tests to have parameterized constructors
 * annotated with @Inject, and it allows methods annotated with @Before, @After,
 * @BeforeClass, @AfterClass, and @Test to have parameters as well.
 * 
 * 
 * Note, the methods should not be annotated with @Inject since those methods
 * are called by Guice when an instance is constructed. This runner also assumes
 * that all parameters can be instantiated by Guice; exceptions will be thrown
 * if this is not the case.
 * 
 * 
 * Use the @TestModule annotation to specify the Module to use when creating the
 * Injector.
 * 
 */
public class GuiceTestRunner extends BlockJUnit4ClassRunner {
	private final Class testClass;
	private final Injector injector;
	
	public GuiceTestRunner(Class klass) throws InitializationError {
		super(klass);
		this.testClass = klass;
		
		TestModule testModule = klass.getAnnotation(TestModule.class);
		
		if (testModule != null) {
			try {
				Module m = (Module) testModule.value().newInstance();
				this.injector = Guice.createInjector(m);
			} catch (Exception e) {
				List t = new ArrayList();
				t.add(e);
				throw new InitializationError(t);
			}
		} else {
			// no TestModule annotation, so use no module
			this.injector = Guice.createInjector();
		}
	}
	
	@Override
	protected Object createTest() {
		return injector.getInstance(testClass);
	}
	
	@Override
	protected Statement methodInvoker(FrameworkMethod method, Object test) {
		return new InjectInvokeMethod(this, method, test);
	}
	
	/** Overridden to return InjectRunAfters instead of RunAfters. */
	@Override
	protected Statement withBeforeClasses(Statement statement) {
		List befores = getTestClass().getAnnotatedMethods(BeforeClass.class);
		return new InjectRunBefores(this, statement, befores, null);
	}

	/** Overridden to return InjectRunAfters instead of RunAfters. */
	@Override
	protected Statement withAfterClasses(Statement statement) {
		List afters = getTestClass().getAnnotatedMethods(AfterClass.class);
		return new InjectRunAfters(this, statement, afters, null);
	}
	
	/** Overridden to return InjectRunBefores instead of RunBefores. */
	@Override
	protected Statement withBefores(FrameworkMethod method, Object target, Statement statement) {
		List befores = getTestClass().getAnnotatedMethods(Before.class);
		return new InjectRunBefores(this, statement, befores, target);
	}

	/** Overridden to return InjectRunAfters instead of RunAfters. */
	@Override
	protected Statement withAfters(FrameworkMethod method, Object target, Statement statement) {
		List afters = getTestClass().getAnnotatedMethods(After.class);
		return new InjectRunAfters(this, statement, afters, target);
	}
	
	/** This is now somewhat of a misnomer and no longer follows the
	 * expected contract. It is effectively validatePublicVoid() and
	 * allows for multiple argument methods. */
	@Override
	protected void validatePublicVoidNoArgMethods(Class annotation, boolean isStatic, List errors) {
		// copied, and then modified implementation from ParentRunner
		List methods = getTestClass().getAnnotatedMethods(annotation);

		for (FrameworkMethod eachTestMethod: methods)
			eachTestMethod.validatePublicVoid(isStatic, errors); // used to be validatePublicVoidNoArg()
	}
	
	@Override
	protected void validateZeroArgConstructor(List errors) {
		// do nothing, constructor can take any arguments
	}
	
	/** This method should be used by Statements that need to 
	 * invoke FrameworkMethods, and use the returned array as
	 * the parameters to that method. */
	public Object[] injectParameters(Method m) {
		// FIXME: we should build up the parameters in a safer way
		Class[] parameterTypes = m.getParameterTypes();
		Object[] injectedParameters = new Object[parameterTypes.length];
		for (int i = 0; i < parameterTypes.length; i++) {
			injectedParameters[i] = injector.getInstance(parameterTypes[i]);
		}
		
		return injectedParameters;
	}
}