BatchingIterableTest.java

package org.molgenis.util;

import org.testng.annotations.BeforeClass;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

import java.util.*;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertFalse;

public class BatchingIterableTest
{
	public static List<Integer> ITEMS_LIST;

	@BeforeClass
	public static void setUpBeforeClass()
	{
		ITEMS_LIST = Arrays.asList(1, 2, 3, 4);
	}

	// parameterized test testing combinations of offset, limit, batchSize
	@DataProvider(name = "iteratorTest")
	public static Iterator<Object[]> createData1()
	{
		List<Object[]> paramList = new ArrayList<Object[]>();

		for (int batchSize = 1; batchSize < ITEMS_LIST.size() + 1; ++batchSize)
		{
			for (int offset = 0; offset < ITEMS_LIST.size(); ++offset)
			{
				// add limit that is larger than the number of items
				for (int limit = 1; limit < ITEMS_LIST.size() - offset + 1; ++limit)
				{
					paramList.add(new Object[] { offset, limit, batchSize });
				}
				// add limit=0 (no limit) add the end to enable friendly printing order
				paramList.add(new Object[] { offset, 0, batchSize });
			}
		}

		return paramList.iterator();
	}

	@Test(dataProvider = "iteratorTest")
	public void iterator(int offset, int limit, int batchSize)
	{
		Iterable<Integer> iterable = new BatchingIterable<Integer>(batchSize, offset, limit)
		{
			@Override
			protected List<Integer> getBatch(int offset, int batchSize)
			{
				List<Integer> batchList;
				if (offset < ITEMS_LIST.size())
				{
					int toIndex = offset + Math.min(batchSize, ITEMS_LIST.size() - offset);
					batchList = ITEMS_LIST.subList(offset, toIndex);
				}
				else
				{
					batchList = Collections.emptyList();
				}
				return batchList;
			}
		};

		int expectedValue = offset + 1;
		int actualNrItems = 0;
		for (Iterator<Integer> it = iterable.iterator(); it.hasNext(); )
		{
			int intValue = it.next().intValue();
			assertEquals(intValue, expectedValue++);
			++actualNrItems;
		}

		// enable to print batch info
		// System.out.println(String.format("[offset=%d, limit=%d, batchSize=%d]", offset, limit, batchSize) + ": "
		// + StringUtils.join(iterable, ','));
		int expectedNrItems = limit == 0 ? ITEMS_LIST.size() - offset : limit;
		assertEquals(actualNrItems, expectedNrItems,
				String.format("[offset=%d, limit=%d, batchSize=%d]", offset, limit, batchSize));
	}

	@Test
	public void iteratorNoResults()
	{
		Iterable<Integer> iterable = new BatchingIterable<Integer>(1000, 0, 10)
		{
			@Override
			protected List<Integer> getBatch(int offset, int batchSize)
			{
				return Collections.emptyList();
			}
		};
		assertFalse(iterable.iterator().hasNext());
	}
}