UniformSamplerTest.java

/*
 * Copyright 2013, 2014 Deutsche Nationalbibliothek
 *
 * 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.culturegraph.mf.statistics;

import static org.mockito.Mockito.inOrder;

import java.util.Arrays;

import org.culturegraph.mf.framework.ObjectReceiver;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;
import org.mockito.InOrder;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;


/**
 * Tests for class {@link UniformSampler}.
 *
 * @author Christoph Böhme
 *
 */
@RunWith(Parameterized.class)
public final class UniformSamplerTest {

	private static final long SEED = 1;  // Use a fixed random seed to make the test repeatable
	private static final int SAMPLE_SIZE = 5;

	private static final int LARGE_SET = 100;
	private static final int SMALL_SET = 3;

	private UniformSampler<String> sampler;

	@Mock
	private ObjectReceiver<String> receiver;

	private final int setSize;
	private final String[] expected;

	public UniformSamplerTest(final int setSize, final String[] expected) {
		this.setSize = setSize;
		this.expected = expected.clone();
	}

	@Parameters
	public static Iterable<Object[]> data() {
		return Arrays.asList(new Object[][] {
				{ LARGE_SET, new String[] { "93", "43", "78", "35", "42" } },
				{ SMALL_SET, new String[] { "0", "1", "2" } },
			});
	}

	@Before
	public void setup() {
		MockitoAnnotations.initMocks(this);
		sampler = new UniformSampler<String>(SAMPLE_SIZE);
		sampler.setSeed(SEED);
		sampler.setReceiver(receiver);
	}

	@Test
	public void testShouldEmitARandomSubsetOfTheInputObjects() {
		for(int i = 0; i < setSize; ++i) {
			sampler.process(Integer.toString(i));
		}
		sampler.closeStream();

		final InOrder ordered = inOrder(receiver);
		for(int i = 0; i < expected.length; ++i) {
			ordered.verify(receiver).process(expected[i]);
		}
		ordered.verify(receiver).closeStream();
	}

}