org.wisepersist.gwtmockito.ng.fakes.FakeClientBundleProvider.java Source code

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Here is the source code for org.wisepersist.gwtmockito.ng.fakes.FakeClientBundleProvider.java

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/*
 * Copyright (c) 2013 Google Inc.
 * Copyright (c) 2016 WisePersist.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.wisepersist.gwtmockito.ng.fakes;

import com.google.gwt.core.client.GWT;
import com.google.gwt.resources.client.ClientBundle;
import com.google.gwt.resources.client.CssResource;
import com.google.gwt.resources.client.ResourceCallback;
import com.google.gwt.resources.client.ResourcePrototype;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlUtils;
import com.google.gwt.safehtml.shared.SafeUri;
import com.google.gwt.safehtml.shared.UriUtils;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;

/**
 * Provides fake implementations of {@link ClientBundle}s. Any methods in the
 * bundle returning {@link CssResource}s will GWT.create the {@link CssResource}
 * (which by default will cause it to be generated by
 * {@link FakeMessagesProvider}. Other types of resources will be generated to
 * return unique values from their getText() or getSafeUri() methods.
 *
 * @author ekuefler@google.com (Erik Kuefler)
 */
public class FakeClientBundleProvider implements FakeProvider<ClientBundle> {

    /**
     * Returns a new instance of the given type that implements methods as
     * described in the class description.
     *
     * @param type Interface to be implemented by the returned type.
     */
    @Override
    public final ClientBundle getFake(final Class<?> type) {
        return (ClientBundle) createNewProxyInstance(type, new InvocationHandler() {
            @Override
            public Object invoke(final Object proxy, final Method method, final Object[] args) //NOPMD
                    throws Exception {
                final Class<?> returnType = method.getReturnType();
                final Object result;
                if (CssResource.class.isAssignableFrom(returnType)) {
                    result = GWT.create(returnType);
                } else {
                    result = createFakeResource(returnType, method.getName());
                }
                return result;
            }
        });
    }

    /**
     * Creates a new proxy instance with type and invocation handler specified.
     *
     * @param type The type specified.
     * @param handler The invocation handler specified.
     * @param <T> The generic type specified.
     * @return The proxy instance created.
     */
    @SuppressWarnings("unchecked") // safe since the proxy implements type
    private <T> T createNewProxyInstance(final Class<T> type, final InvocationHandler handler) {
        return (T) Proxy.newProxyInstance(FakeClientBundleProvider.class.getClassLoader(), new Class<?>[] { type },
                handler); //NOPMD
    }

    /**
     * Creates a fake resource class that returns its own name where possible.
     *
     * @param type The type specified.
     * @param name The name specified.
     * @param <T> The generic type specified.
     * @return Fake resource created.
     */
    @SuppressWarnings("unchecked") // safe since the proxy implements type
    private <T> T createFakeResource(final Class<T> type, final String name) {
        return createNewProxyInstance(type, new InvocationHandler() {
            @Override
            public Object invoke(final Object proxy, final Method method, final Object[] args) //NOPMD
                    throws Exception {
                return doInvoke(method, args, name);
            }
        });
    }

    /**
     * Fake invoking on a specified method with arguments.
     *
     * @param method The method specified.
     * @param args The arguments specified.
     * @param name The name specified.
     * @return The result object.
     */
    private Object doInvoke(final Method method, final Object[] args, final String name) {
        final Object result;
        final Class<?> returnType = method.getReturnType();
        if (returnType == String.class) {
            result = name;
        } else if (returnType == SafeHtml.class) {
            result = SafeHtmlUtils.fromTrustedString(name);
        } else if (returnType == SafeUri.class) {
            result = UriUtils.fromTrustedString(name);
        } else if (returnType == boolean.class) {
            result = false;
        } else if (returnType == int.class) {
            result = 0;
        } else if (method.getParameterTypes()[0] == ResourceCallback.class) {
            result = createFakeForResourceCallback(args[0], name);
        } else {
            throw new IllegalArgumentException("Unexpected return type for method " + method.getName());
        }
        return result;
    }

    /**
     * Creates fake resource for {@link ResourceCallback}.
     *
     * @param arg The object arg specified.
     * @param name The name specified.
     * @return Null object as nothing need to be returned.
     */
    @SuppressWarnings("unchecked") // safe since the proxy implements type
    private Object createFakeForResourceCallback(final Object arg, final String name) {
        // Read the underlying resource type out of the generic parameter
        // in the method's argument
        final Class<?> resourceType = (Class<?>) ((ParameterizedType) arg.getClass().getGenericInterfaces()[0])
                .getActualTypeArguments()[0];
        ((ResourceCallback<ResourcePrototype>) arg)
                .onSuccess((ResourcePrototype) createFakeResource(resourceType, name));
        return null;
    }
}