src/main/java/org/apache/hadoop/mrunit/MapDriver.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 static org.apache.hadoop.mrunit.internal.util.ArgumentChecker.*;

import java.io.IOException;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.InputFormat;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputFormat;
import org.apache.hadoop.mrunit.internal.counters.CounterWrapper;
import org.apache.hadoop.mrunit.internal.mapred.MockReporter;
import org.apache.hadoop.mrunit.internal.output.MockOutputCreator;
import org.apache.hadoop.mrunit.internal.output.OutputCollectable;
import org.apache.hadoop.mrunit.types.Pair;
import org.apache.hadoop.util.ReflectionUtils;

/**
 * Harness that allows you to test a Mapper instance. You provide the input
 * (k, v)* pairs that should be sent to the Mapper, and outputs you expect to be
 * sent by the Mapper to the collector for those inputs. By calling runTest(),
 * the harness will deliver the input to the Mapper and will check its outputs
 * against the expected results.
 */
public class MapDriver<K1, V1, K2, V2> extends MapDriverBase<K1, V1, K2, V2, MapDriver<K1, V1, K2, V2>> {

  public static final Log LOG = LogFactory.getLog(MapDriver.class);

  private Mapper<K1, V1, K2, V2> myMapper;
  private Counters counters;

  private final MockOutputCreator<K2, V2> mockOutputCreator = new MockOutputCreator<K2, V2>();

  public MapDriver(final Mapper<K1, V1, K2, V2> m) {
    this();
    setMapper(m);
  }

  public MapDriver() {
    setCounters(new Counters());
  }

  /** @return the counters used in this test */
  public Counters getCounters() {
    return counters;
  }

  /**
   * Sets the counters object to use for this test.
   *
   * @param ctrs
   *          The counters object to use.
   */
  public void setCounters(final Counters ctrs) {
    counters = ctrs;
    counterWrapper = new CounterWrapper(counters);
  }

  /** Sets the counters to use and returns self for fluent style */
  public MapDriver<K1, V1, K2, V2> withCounters(final Counters ctrs) {
    setCounters(ctrs);
    return this;
  }

  /**
   * Set the Mapper instance to use with this test driver
   *
   * @param m
   *          the Mapper instance to use
   */
  public void setMapper(final Mapper<K1, V1, K2, V2> m) {
    myMapper = returnNonNull(m);
  }

  /** Sets the Mapper instance to use and returns self for fluent style */
  public MapDriver<K1, V1, K2, V2> withMapper(final Mapper<K1, V1, K2, V2> m) {
    setMapper(m);
    return this;
  }

  /**
   * @return the Mapper object being used by this test
   */
  public Mapper<K1, V1, K2, V2> getMapper() {
    return myMapper;
  }

  /**
   * Configure {@link Mapper} to output with a real {@link OutputFormat}. Set
   * {@link InputFormat} to read output back in for use with run* methods
   *
   * @param outputFormatClass
   * @param inputFormatClass
   * @return this for fluent style
   */
  @SuppressWarnings("rawtypes")
  public MapDriver<K1, V1, K2, V2> withOutputFormat(
      final Class<? extends OutputFormat> outputFormatClass,
      final Class<? extends InputFormat> inputFormatClass) {
    mockOutputCreator.setMapredFormats(outputFormatClass, inputFormatClass);
    return this;
  }

  @Override
  public List<Pair<K2, V2>> run() throws IOException {
    try {
      preRunChecks(myMapper);
      initDistributedCache();
      final OutputCollectable<K2, V2> outputCollectable = mockOutputCreator
          .createMapredOutputCollectable(getConfiguration(),
              getOutputSerializationConfiguration());
      final MockReporter reporter = new MockReporter(
          MockReporter.ReporterType.Mapper, getCounters(),
          getMapInputPath());

      ReflectionUtils.setConf(myMapper, new JobConf(getConfiguration()));

      for (Pair<K1, V1> kv : inputs) {
        myMapper.map(kv.getFirst(), kv.getSecond(), outputCollectable, reporter);
      }

      myMapper.close();

      return outputCollectable.getOutputs();
    } finally {
      cleanupDistributedCache();
    }
  }

  @Override
  public String toString() {
    return "MapDriver (" + myMapper + ")";
  }

  /**
   * Returns a new MapDriver without having to specify the generic types on the
   * right hand side of the object create statement.
   *
   * @return new MapDriver
   */
  public static <K1, V1, K2, V2> MapDriver<K1, V1, K2, V2> newMapDriver() {
    return new MapDriver<K1, V1, K2, V2>();
  }

  /**
   * Returns a new MapDriver without having to specify the generic types on the
   * right hand side of the object create statement.
   *
   * @param mapper
   * @return new MapDriver
   */
  public static <K1, V1, K2, V2> MapDriver<K1, V1, K2, V2> newMapDriver(
      final Mapper<K1, V1, K2, V2> mapper) {
    return new MapDriver<K1, V1, K2, V2>(mapper);
  }
}