ExpectProxy.java

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 * Copyright 2008-2009 Sun Microsystems, Inc. All rights reserved.
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 * The contents of this file are subject to the terms of the Common Development
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 * except in compliance with the License.
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 * and include the License file at http://opensource.org/licenses/cddl1.php.
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package org.identityconnectors.dbcommon;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.List;

/**
 * This is a Test helper class for testing expected method calls and return
 * values of interfaces.
 * <p>
 * Limitation:
 * </p>
 * <p>
 * First implementation supports just a method name checking
 * </p>
 *
 * @version $Revision 1.0$
 * @param <T>
 *            Type of the interface for testing
 * @since 1.0
 */
public class ExpectProxy<T> implements InvocationHandler {

    private final List<String> methodNames = new ArrayList<String>();
    private final List<Object> returnValues = new ArrayList<Object>();
    private int count = 0;

    /**
     * Program the expected function call.
     *
     * @param methodName
     *            the expected method name
     * @param retVal
     *            the expected return value or proxy
     * @return the proxy
     */
    public ExpectProxy<T> expectAndReturn(final String methodName, final Object retVal) {
        this.methodNames.add(methodName);
        this.returnValues.add(retVal);
        return this;
    }

    /**
     * Program the expected method call.
     *
     * @param methodName
     *            the expected method name
     * @return the proxy
     */
    public ExpectProxy<T> expect(final String methodName) {
        this.methodNames.add(methodName);
        // returnValues must have same number of values as methodNames
        this.returnValues.add(null);
        return this;
    }

    /**
     * Program the expected method call.
     *
     * @param methodName
     *            the expected method name
     * @param throwEx
     *            the expected exception
     * @return the proxy
     */
    public ExpectProxy<T> expectAndThrow(final String methodName, final Throwable throwEx) {
        return this.expectAndReturn(methodName, throwEx);
    }

    /**
     * Test that all expected was called in the order.
     *
     * @return true/false all was called
     */
    public boolean isDone() {
        return count == methodNames.size();
    }

    /**
     * The InvocationHandler method.
     */
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        String ext = "";
        if (methodNames.size() > count) {
            final String mname = this.methodNames.get(count);
            ext = " The expected call no: " + (count + 1) + " was " + mname + ".";
            if (method.getName().equals(mname)) {
                final Object ret = returnValues.get(count++);
                if (ret instanceof Throwable) {
                    throw (Throwable) ret;
                }
                return ret;
            }
        }
        throw new AssertionError("The call of method :" + method + " was not expected." + ext
                + " Please call expectAndReturn(methodName,retVal) to fix it");
    }

    /**
     * Return the Proxy implementation of the Interface.
     *
     * @param clazz
     *            of the interface
     * @return the proxy
     */
    @SuppressWarnings("unchecked")
    public T getProxy(Class<T> clazz) {
        ClassLoader cl = getClass().getClassLoader();
        Class<?> intef[] = new Class<?>[] { clazz };
        return (T) Proxy.newProxyInstance(cl, intef, this);
    }
}