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/**
 * Copyright 2014 Netflix, Inc.
 * 
 * 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 rx.observers;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import rx.Notification;
import rx.Observer;

/**
 * Observer usable for unit testing to perform assertions, inspect received events or wrap a mocked Observer.
 */
public class TestObserver implements Observer {

    private final Observer delegate;
    private final ArrayList onNextEvents = new ArrayList();
    private final ArrayList onErrorEvents = new ArrayList();
    private final ArrayList> onCompletedEvents = new ArrayList>();

    public TestObserver(Observer delegate) {
        this.delegate = delegate;
    }

    public TestObserver() {
        this.delegate = Observers.empty();
    }

    @Override
    public void onCompleted() {
        onCompletedEvents.add(Notification. createOnCompleted());
        delegate.onCompleted();
    }

    /**
     * Get the {@link Notification}s representing each time this observer was notified of sequence completion
     * via {@link #onCompleted}, as a {@link List}.
     *
     * @return a list of Notifications representing calls to this observer's {@link #onCompleted} method
     */
    public List> getOnCompletedEvents() {
        return Collections.unmodifiableList(onCompletedEvents);
    }

    @Override
    public void onError(Throwable e) {
        onErrorEvents.add(e);
        delegate.onError(e);
    }

    /**
     * Get the {@link Throwable}s this observer was notified of via {@link #onError} as a {@link List}.
     *
     * @return a list of Throwables passed to this observer's {@link #onError} method
     */
    public List getOnErrorEvents() {
        return Collections.unmodifiableList(onErrorEvents);
    }

    @Override
    public void onNext(T t) {
        onNextEvents.add(t);
        delegate.onNext(t);
    }

    /**
     * Get the sequence of items observed by this observer, as an ordered {@link List}.
     *
     * @return a list of items observed by this observer, in the order in which they were observed
     */
    public List getOnNextEvents() {
        return Collections.unmodifiableList(onNextEvents);
    }

    /**
     * Get a list containing all of the items and notifications received by this observer, where the items
     * will be given as-is, any error notifications will be represented by their {@code Throwable}s, and any
     * sequence-complete notifications will be represented by their {@code Notification} objects.
     *
     * @return a {@link List} containing one item for each item or notification received by this observer, in
     *         the order in which they were observed or received
     */
    public List