ViewPagerIdlingResource.java

package com.llamacorp.equate.test.IdlingResource;

import android.support.test.espresso.IdlingResource;
import android.support.v4.view.ViewPager;

/**
 *  Idling resource that waits for a view pager to finish it's scroll animation
 *  before testing cna resume.
 */
public class ViewPagerIdlingResource implements IdlingResource {
	private final String mName;
	private boolean mIdle = true; // Default to idle since we can't query the scroll state.
	private ResourceCallback mResourceCallback;

	public ViewPagerIdlingResource(ViewPager viewPager, String name) {
		viewPager.addOnPageChangeListener(new ViewPagerListener());
		mName = name;
	}

	@Override
	public String getName() {
		return mName;
	}

	@Override
	public boolean isIdleNow() {
		return mIdle;
	}

	@Override
	public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
		mResourceCallback = resourceCallback;
	}

	private class ViewPagerListener extends ViewPager.SimpleOnPageChangeListener {
		@Override
		public void onPageScrollStateChanged(int state) {
			mIdle = (state == ViewPager.SCROLL_STATE_IDLE
					  // Treat dragging as idle, or Espresso will block itself when swiping.
					  || state == ViewPager.SCROLL_STATE_DRAGGING);
			if (mIdle && mResourceCallback != null) {
				mResourceCallback.onTransitionToIdle();
			}
		}
	}
}