src/main/java/org/apache/hadoop/mrunit/MapDriverBase.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 java.io.IOException;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mrunit.types.Pair;

/**
 * Harness that allows you to test a Mapper instance. You provide the input key
 * and value 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. This is designed to handle a single (k, v) ->
 * (k, v)* case from the Mapper, representing a single unit test. Multiple input
 * (k, v) pairs should go in separate unit tests.
 */
public abstract class MapDriverBase<K1, V1, K2, V2> extends
    TestDriver<K1, V1, K2, V2> {

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

  protected K1 inputKey;
  protected V1 inputVal;

  /**
   * Sets the input key to send to the mapper
   * 
   * @param key
   */
  public void setInputKey(final K1 key) {
    inputKey = copy(key);
  }

  public K1 getInputKey() {
    return inputKey;
  }

  /**
   * Sets the input value to send to the mapper
   * 
   * @param val
   */
  public void setInputValue(final V1 val) {
    inputVal = copy(val);
  }

  public V1 getInputValue() {
    return inputVal;
  }

  /**
   * Sets the input to send to the mapper
   * 
   */
  public void setInput(final K1 key, final V1 val) {
    setInputKey(key);
    setInputValue(val);
  }

  /**
   * Sets the input to send to the mapper
   * 
   * @param inputRecord
   *          a (key, val) pair
   */
  public void setInput(final Pair<K1, V1> inputRecord) {
    setInputKey(inputRecord.getFirst());
    setInputValue(inputRecord.getSecond());
  }

  /**
   * Adds an output (k, v) pair we expect from the Mapper
   * 
   * @param outputRecord
   *          The (k, v) pair to add
   */
  public void addOutput(final Pair<K2, V2> outputRecord) {
    addOutput(outputRecord.getFirst(), outputRecord.getSecond());
  }

  /**
   * Adds a (k, v) pair we expect as output from the mapper
   * 
   */
  public void addOutput(final K2 key, final V2 val) {
    expectedOutputs.add(copyPair(key, val));
  }

  /**
   * Expects an input of the form "key \t val" Forces the Mapper input types to
   * Text.
   * 
   * @param input
   *          A string of the form "key \t val".
   * @deprecated No replacement due to lack of type safety and incompatibility
   *             with non Text Writables
   */
  @Deprecated
  @SuppressWarnings("unchecked")
  public void setInputFromString(final String input) {
    final Pair<Text, Text> inputPair = parseTabbedPair(input);
    setInputKey((K1) inputPair.getFirst());
    setInputValue((V1) inputPair.getSecond());
  }

  /**
   * Expects an input of the form "key \t val" Forces the Mapper output types to
   * Text.
   * 
   * @param output
   *          A string of the form "key \t val". Trims any whitespace.
   * @deprecated No replacement due to lack of type safety and incompatibility
   *             with non Text Writables
   */
  @Deprecated
  @SuppressWarnings("unchecked")
  public void addOutputFromString(final String output) {
    addOutput((Pair<K2, V2>) parseTabbedPair(output));
  }

  @Override
  public abstract List<Pair<K2, V2>> run() throws IOException;

  @Override
  public void runTest(final boolean orderMatters) {
    LOG.debug("Mapping input (" + inputKey + ", " + inputVal + ")");
    try {
      final List<Pair<K2, V2>> outputs = run();
      validate(outputs, orderMatters);
      validate(counterWrapper);
    } catch (final IOException ioe) {
      LOG.error("IOException in mapper", ioe);
      throw new RuntimeException("IOException in mapper: ", ioe);
    }
  }
}