cakephp/tests/TestCase/Collection/Iterator/MapReduceTest.php

<?php
/**
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 */
namespace Cake\Test\TestCase\Collection\Iterator;

use ArrayIterator;
use Cake\Collection\Iterator\MapReduce;
use Cake\TestSuite\TestCase;

/**
 * Tests MapReduce class
 *
 */
class MapReduceTest extends TestCase {

/**
 * Tests the creation of an inversed index of words to documents using
 * MapReduce
 *
 * @return void
 */
	public function testInvertedIndexCreation() {
		$data = [
			'document_1' => 'Dogs are the most amazing animal in history',
			'document_2' => 'History is not only amazing but boring',
			'document_3' => 'One thing that is not boring is dogs'
		];
		$mapper = function($row, $document, $mr) {
			$words = array_map('strtolower', explode(' ', $row));
			foreach ($words as $word) {
				$mr->emitIntermediate($document, $word);
			}
		};
		$reducer = function($documents, $word, $mr) {
			$mr->emit(array_unique($documents), $word);
		};
		$results = new MapReduce(new ArrayIterator($data), $mapper, $reducer);
		$expected = [
			'dogs' => ['document_1', 'document_3'],
			'are' => ['document_1'],
			'the' => ['document_1'],
			'most' => ['document_1'],
			'amazing' => ['document_1', 'document_2'],
			'animal' => ['document_1'],
			'in' => ['document_1'],
			'history' => ['document_1', 'document_2'],
			'is' => ['document_2', 'document_3'],
			'not' => ['document_2', 'document_3'],
			'only' => ['document_2'],
			'but' => ['document_2'],
			'boring' => ['document_2', 'document_3'],
			'one' => ['document_3'],
			'thing' => ['document_3'],
			'that' => ['document_3']
		];
		$this->assertEquals($expected, iterator_to_array($results));
	}

/**
 * Tests that it is possible to use the emit function directly in the mapper
 *
 * @return void
 */
	public function testEmitFinalInMapper() {
		$data = ['a' => ['one', 'two'], 'b' => ['three', 'four']];
		$mapper = function ($row, $key, $mr) {
			foreach ($row as $number) {
				$mr->emit($number);
			}
		};
		$results = new MapReduce(new ArrayIterator($data), $mapper);
		$expected = ['one', 'two', 'three', 'four'];
		$this->assertEquals($expected, iterator_to_array($results));
	}

/**
 * Tests that a reducer is required when there are intermediate results
 *
 * @expectedException \LogicException
 * @return void
 */
	public function testReducerRequired() {
		$data = ['a' => ['one', 'two'], 'b' => ['three', 'four']];
		$mapper = function ($row, $key, $mr) {
			foreach ($row as $number) {
				$mr->emitIntermediate('a', $number);
			}
		};
		$results = new MapReduce(new ArrayIterator($data), $mapper);
		iterator_to_array($results);
	}

}