added SpanContaining query

src/Query/Span/SpanContainingQuery.php

+<?php
+
+/*
+ * This file is part of the ONGR package.
+ *
+ * (c) NFQ Technologies UAB <info@nfq.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ONGR\ElasticsearchDSL\Query\Span;
+
+/**
+ * Elasticsearch span containing query.
+ *
+ * @link https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-span-containing-query.html
+ */
+class SpanContainingQuery implements SpanQueryInterface
+{
+    /**
+     * @param SpanQueryInterface
+     */
+    private $big;
+
+    /**
+     * @param SpanQueryInterface
+     */
+    private $little;
+
+    /**
+     * @param SpanQueryInterface $big
+     * @param SpanQueryInterface $little
+     */
+    public function __construct(SpanQueryInterface $big, SpanQueryInterface $little)
+    {
+        $this->big = $big;
+        $this->little = $little;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getType()
+    {
+        return 'span_containing';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function toArray()
+    {
+        $out = [
+            'little' => $this->little->toArray(),
+            'big' => $this->big->toArray(),
+        ];
+
+        return [$this->getType() => $out];
+    }
+}

tests/Query/Span/SpanContainingQueryTest.php

+<?php
+
+/*
+ * This file is part of the ONGR package.
+ *
+ * (c) NFQ Technologies UAB <info@nfq.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace ONGR\ElasticsearchDSL\Tests\Query\Span;
+
+use ONGR\ElasticsearchDSL\Query\Span\SpanContainingQuery;
+
+/**
+ * Unit test for SpanContainingQuery.
+ */
+class SpanContainingQueryTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests for toArray().
+     */
+    public function testToArray()
+    {
+        $query = new SpanContainingQuery(
+            $this->getSpanQueryMack('foo'),
+            $this->getSpanQueryMack('bar')
+        );
+        $result = [
+            'span_containing' => [
+                'little' => [
+                    'span_term' => ['user' => 'bar'],
+                ],
+                'big' => [
+                    'span_term' => ['user' => 'foo'],
+                ],
+            ],
+        ];
+        $this->assertEquals($result, $query->toArray());
+    }
+
+    /**
+     * @param string $value
+     *
+     * @returns \PHPUnit_Framework_MockObject_MockObject
+     */
+    private function getSpanQueryMack($value)
+    {
+        $mock = $this->getMock('ONGR\ElasticsearchDSL\Query\Span\SpanQueryInterface');
+        $mock
+            ->expects($this->once())
+            ->method('toArray')
+            ->willReturn(['span_term' => ['user' => $value]]);
+        return $mock;
+    }
+}