src/test/java/org/apache/hadoop/mrunit/TestMapOutputShuffler.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.hadoop.mrunit;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mrunit.types.Pair;
import org.junit.Before;
import org.junit.Test;

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

import static org.apache.hadoop.mrunit.ExtendedAssert.assertListEquals;
import static org.junit.Assert.assertEquals;

public class TestMapOutputShuffler {
  private MapOutputShuffler<Text, Text> shuffler;

  @Before
  public void setUp() {
    shuffler = new MapOutputShuffler<Text, Text>(null, null, null);
  }

  @Test
  public void testEmptyShuffle() {
    final List<Pair<Text, Text>> inputs = new ArrayList<Pair<Text, Text>>();
    final List<Pair<Text, List<Text>>> outputs = shuffler.shuffle(inputs);
    assertEquals(0, outputs.size());
  }

  // just shuffle a single (k, v) pair
  @Test
  public void testSingleShuffle() {
    final List<Pair<Text, Text>> inputs = new ArrayList<Pair<Text, Text>>();
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("b")));

    final List<Pair<Text, List<Text>>> outputs = shuffler.shuffle(inputs);

    final List<Pair<Text, List<Text>>> expected = new ArrayList<Pair<Text, List<Text>>>();
    final List<Text> sublist = new ArrayList<Text>();
    sublist.add(new Text("b"));
    expected.add(new Pair<Text, List<Text>>(new Text("a"), sublist));

    assertListEquals(expected, outputs);
  }

  // shuffle multiple values from the same key.
  @Test
  public void testShuffleOneKey() {
    final List<Pair<Text, Text>> inputs = new ArrayList<Pair<Text, Text>>();
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("b")));
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("c")));

    final List<Pair<Text, List<Text>>> outputs = shuffler.shuffle(inputs);

    final List<Pair<Text, List<Text>>> expected = new ArrayList<Pair<Text, List<Text>>>();
    final List<Text> sublist = new ArrayList<Text>();
    sublist.add(new Text("b"));
    sublist.add(new Text("c"));
    expected.add(new Pair<Text, List<Text>>(new Text("a"), sublist));

    assertListEquals(expected, outputs);
  }

  // shuffle multiple keys
  @Test
  public void testMultiShuffle1() {
    final List<Pair<Text, Text>> inputs = new ArrayList<Pair<Text, Text>>();
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("x")));
    inputs.add(new Pair<Text, Text>(new Text("b"), new Text("z")));
    inputs.add(new Pair<Text, Text>(new Text("b"), new Text("w")));
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("y")));

    final List<Pair<Text, List<Text>>> outputs = shuffler.shuffle(inputs);

    final List<Pair<Text, List<Text>>> expected = new ArrayList<Pair<Text, List<Text>>>();
    final List<Text> sublist1 = new ArrayList<Text>();
    sublist1.add(new Text("x"));
    sublist1.add(new Text("y"));
    expected.add(new Pair<Text, List<Text>>(new Text("a"), sublist1));

    final List<Text> sublist2 = new ArrayList<Text>();
    sublist2.add(new Text("z"));
    sublist2.add(new Text("w"));
    expected.add(new Pair<Text, List<Text>>(new Text("b"), sublist2));

    assertListEquals(expected, outputs);
  }

  // shuffle multiple keys that are out-of-order to start.
  @Test
  public void testMultiShuffle2() {
    final List<Pair<Text, Text>> inputs = new ArrayList<Pair<Text, Text>>();
    inputs.add(new Pair<Text, Text>(new Text("b"), new Text("z")));
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("x")));
    inputs.add(new Pair<Text, Text>(new Text("b"), new Text("w")));
    inputs.add(new Pair<Text, Text>(new Text("a"), new Text("y")));

    final List<Pair<Text, List<Text>>> outputs = shuffler.shuffle(inputs);

    final List<Pair<Text, List<Text>>> expected = new ArrayList<Pair<Text, List<Text>>>();
    final List<Text> sublist1 = new ArrayList<Text>();
    sublist1.add(new Text("x"));
    sublist1.add(new Text("y"));
    expected.add(new Pair<Text, List<Text>>(new Text("a"), sublist1));

    final List<Text> sublist2 = new ArrayList<Text>();
    sublist2.add(new Text("z"));
    sublist2.add(new Text("w"));
    expected.add(new Pair<Text, List<Text>>(new Text("b"), sublist2));

    assertListEquals(expected, outputs);
  }
}