org.wisepersist.gwtmockito.ng.fakes.FakeMessagesProvider Maven / Gradle / Ivy

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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.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlUtils;
import com.google.gwt.safehtml.shared.SafeUri;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;

/**
 * Provides fake implementations of {@link com.google.gwt.i18n.client.Messages},
 * {@link com.google.gwt.resources.client.CssResource}, and
 * {@link com.google.gwt.safehtml.client.SafeHtmlTemplates}. The fake
 * implementations implement methods by returning Strings of SafeHtml instances
 * based on the method name and the arguments passed to it. The exact format of
 * the message is undefined and is subject to change.
 *
 * @author [email protected] (Erik Kuefler)
 * @param  The actual type class of the {@link FakeProvider} interface.
 */
public class FakeMessagesProvider implements FakeProvider {

  /**
   * 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
  @SuppressWarnings("unchecked") // safe since the proxy implements type
  public final T getFake(final Class type) {
    return (T) Proxy.newProxyInstance(
        FakeMessagesProvider.class.getClassLoader(), new Class[]{type}, //NOPMD
        new InvocationHandler() {
          @Override
          public Object invoke(final Object proxy, final Method method, final Object[] args) //NOPMD
              throws Exception {
            return doInvoke(method, args);
          }
        });
  }

  /**
   * Fake invoking on a specified method with arguments.
   *
   * @param method The method specified.
   * @param args The arguments specified.
   * @return The result object.
   */
  private Object doInvoke(final Method method, final Object... args) {
    final Object result;
    if (method.getName().equals("ensureInjected")) {
      result = true;
    } else if (method.getReturnType() == String.class) {
      result = buildMessage(method, args);
    } else if (method.getReturnType() == SafeHtml.class) {
      result = SafeHtmlUtils.fromTrustedString(buildMessage(method, args));
    } else {
      throw new IllegalArgumentException(
          method.getName() + " must return either String or SafeHtml");
    }
    return result;
  }

  /**
   * Builds message of a method with arguments.
   *
   * @param method The method specified.
   * @param args The arguments specified.
   * @return The message string specified.
   */
  private String buildMessage(final Method method, final Object... args) {
    final StringBuilder message = new StringBuilder(method.getName());
    final String msgStr;
    if (args == null || args.length == 0) {
      msgStr = message.toString();
    } else {
      message.append('(');
      message.append(stringify(args[0]));
      for (final Object arg : Arrays.asList(args).subList(1, args.length)) {
        message.append(", ").append(stringify(arg));
      }
      msgStr = message.append(')').toString();
    }
    return msgStr;
  }

  /**
   * Stringifies an object.
   *
   * @param arg The object arg specified.
   * @return The string of the object.
   */
  private String stringify(final Object arg) {
    final String result;
    if (arg == null) {
      result = "null";
    } else if (arg instanceof SafeHtml) {
      result = ((SafeHtml) arg).asString();
    } else if (arg instanceof SafeUri) {
      result = ((SafeUri) arg).asString();
    } else {
      result = arg.toString();
    }
    return result;
  }
}