org.wisepersist.gwtmockito.ng.fakes.FakeUiBinderProvider 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.core.client.GWT;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiField;

import org.wisepersist.gwtmockito.ng.GwtMockito;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

/**
 * Provides fake implementations of {@link UiBinder}. The fake implementation
 * populates all (non-provided) {@link UiField} in the target type with objects
 * obtained from GWT.create. {@link GwtMockito} can be used to control values
 * returned from GWT.create and hence affect how fields are populated.
 *
 * @author [email protected] (Erik Kuefler)
 */
public class FakeUiBinderProvider implements FakeProvider> {

  /**
   * Returns a new instance of FakeUiBinder that implements the given interface.
   * This is accomplished by returning a dynamic proxy object that delegates
   * calls to a backing FakeUiBinder.
   *
   * @param type Interface to be implemented by the returned type. This must
   *     represent an interface that directly extends {@link UiBinder}.
   */
  @Override
  public final UiBinder getFake(final Class type) {
    return (UiBinder) Proxy.newProxyInstance(
        FakeUiBinderProvider.class.getClassLoader(), //NOPMD
        new Class[]{type}, new InvocationHandler() {
          @Override
          public Object invoke(final Object proxy, final Method method, final Object[] args) //NOPMD
              throws Exception {
            // createAndBindUi is the only method defined by UiBinder
            for (final Field field : getAllFields(args[0].getClass())) {
              if (field.isAnnotationPresent(UiField.class)
                  && !field.getAnnotation(UiField.class).provided()) {
                field.setAccessible(true);
                field.set(args[0], GWT.create(field.getType()));
              }
            }
            return GWT.create(getUiRootType(type));
          }
        });
  }

  /**
   * Gets the UI root type, which is the first generic type parameter of the UiBinder.
   *
   * @param type The class specified.
   * @param  The actual class type.
   * @return The UI root type detected.
   */
  private  Class getUiRootType(final Class type) {
    final ParameterizedType parameterizedType = (ParameterizedType) type.getGenericInterfaces()[0];
    final Type uiRootType = parameterizedType.getActualTypeArguments()[0];
    final Class resultClass;
    if (uiRootType instanceof ParameterizedType) {
      resultClass = (Class) ((ParameterizedType) uiRootType).getRawType();
    } else {
      resultClass = (Class) uiRootType;
    }
    return resultClass;
  }

  /**
   * Gets all fields of the specified type.
   *
   * @param type The class type specified.
   * @return List of fields of the specified type.
   */
  private List getAllFields(final Class type) {
    final List fields = new LinkedList();
    fields.addAll(Arrays.asList(type.getDeclaredFields()));
    if (type.getSuperclass() != null) {
      fields.addAll(getAllFields(type.getSuperclass()));
    }
    return fields;
  }
}