Added Collapse DSL to QueryBuilder (#1724)

That's going to be a bit awkward now: in the PR that added Field Collapsing Support (#1653) I forgot to check in the DSL classes, which made working with it a bit clumsy compared to the usual query methods.
I.e. - as with aggregations - it's now possible to do stuff like this:
```
$collapse
  ->setFieldname('product_id')
  ->setInnerHits(
    $qb->collapse->inner_hits()  // instead of (new Collapse\InnerHits())
  )
```

Let me know if there need to be any changes. Cheers :)

Author: wackerl91

CHANGELOG.md

@@ -25,6 +25,7 @@ All notable changes to this project will be documented in this file based on the
 * Launch tests with PHP 7.4
 * Added `nullable_type_declaration_for_default_null_value`, `no_alias_functions` CS rules [#1706](https://github.com/ruflin/Elastica/pull/1706)
 * Configured `visibility_required` CS rule for constants [#1723](https://github.com/ruflin/Elastica/pull/1723)
+* Added `Collapse` DSL to `QueryBuilder` [#1724](https://github.com/ruflin/Elastica/pull/1724)
 
 ### Deprecated
 

lib/Elastica/QueryBuilder.php

@@ -34,6 +34,7 @@ public function __construct(?Version $version = null)
         $this->addDSL(new DSL\Query());
         $this->addDSL(new DSL\Aggregation());
         $this->addDSL(new DSL\Suggest());
+        $this->addDSL(new DSL\Collapse());
     }
 
     /**
@@ -91,4 +92,14 @@ public function suggest()
     {
         return $this->_facades[DSL::TYPE_SUGGEST];
     }
+
+    /**
+     * Collapse DSL.
+     *
+     * @return DSL\Collapse
+     */
+    public function collapse()
+    {
+        return $this->_facades[DSL::TYPE_COLLAPSE];
+    }
 }

lib/Elastica/QueryBuilder/DSL/Collapse.php

@@ -2,7 +2,7 @@
 
 namespace Elastica\QueryBuilder\DSL;
 
-use Elastica\Query\InnerHits;
+use Elastica\Collapse\InnerHits;
 use Elastica\QueryBuilder\DSL;
 
 /**

lib/Elastica/QueryBuilder/Version.php

@@ -37,6 +37,13 @@ abstract class Version
      */
     protected $suggesters = [];
 
+    /**
+     * supported methods for field collapsing.
+     *
+     * @var array
+     */
+    protected $collapsers = [];
+
     /**
      * returns true if $name is supported, false otherwise.
      */
@@ -49,6 +56,8 @@ public function supports(string $name, string $type): bool
                 return \in_array($name, $this->aggregations, true);
             case DSL::TYPE_SUGGEST:
                 return \in_array($name, $this->suggesters, true);
+            case DSL::TYPE_COLLAPSE:
+                return \in_array($name, $this->collapsers, true);
         }
 
         // disables version check in Facade for custom DSL objects
@@ -78,4 +87,12 @@ public function getSuggesters(): array
     {
         return $this->suggesters;
     }
+
+    /**
+     * @return string[]
+     */
+    public function getCollapsers(): array
+    {
+        return $this->collapsers;
+    }
 }

lib/Elastica/QueryBuilder/Version/Version700.php

@@ -97,4 +97,8 @@ class Version700 extends Version
         'completion',
         'context',
     ];
+
+    protected $collapsers = [
+        'inner_hits',
+    ];
 }

test/Elastica/QueryBuilder/DSL/CollapseTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace Elastica\Test\QueryBuilder\DSL;
+
+use Elastica\Collapse;
+use Elastica\QueryBuilder\DSL;
+
+class CollapseTest extends AbstractDSLTest
+{
+    /**
+     * @group unit
+     */
+    public function testType()
+    {
+        $collapseDSL = new DSL\Collapse();
+
+        $this->assertInstanceOf(DSL::class, $collapseDSL);
+        $this->assertEquals(DSL::TYPE_COLLAPSE, $collapseDSL->getType());
+    }
+
+    /**
+     * @group unit
+     */
+    public function testInterface()
+    {
+        $collapseDSL = new DSL\Collapse();
+
+        $this->_assertImplemented($collapseDSL, 'inner_hits', Collapse\InnerHits::class, []);
+        // Make sure collapse returns an instance of Collapse\InnerHits instead of Query\InnerHits
+        $this->assertInstanceOf(Collapse\InnerHits::class, $collapseDSL->inner_hits());
+    }
+}

test/Elastica/QueryBuilder/VersionTest.php

@@ -17,6 +17,7 @@ public function testVersions()
             new DSL\Query(),
             new DSL\Aggregation(),
             new DSL\Suggest(),
+            new DSL\Collapse(),
         ];
 
         $versions = [
@@ -51,5 +52,12 @@ private function assertVersions(Version $version, array $dsl)
                 'suggester "'.$suggester.'" in '.\get_class($version).' must be defined in '.\get_class($dsl[2])
             );
         }
+
+        foreach ($version->getCollapsers() as $collapser) {
+            $this->assertTrue(
+                \method_exists($dsl[3], $collapser),
+                'suggester "'.$collapser.'" in '.\get_class($version).' must be defined in '.\get_class($dsl[3])
+            );
+        }
     }
 }

test/Elastica/QueryBuilderTest.php

@@ -3,6 +3,7 @@
 namespace Elastica\Test;
 
 use Elastica\Aggregation\AbstractAggregation;
+use Elastica\Collapse;
 use Elastica\Exception\QueryBuilderException;
 use Elastica\Query\AbstractQuery;
 use Elastica\QueryBuilder;
@@ -44,6 +45,10 @@ public function testFacade()
         $this->assertInstanceOf(AbstractQuery::class, $qb->query()->match());
         $this->assertInstanceOf(AbstractAggregation::class, $qb->aggregation()->avg('name'));
         $this->assertInstanceOf(AbstractSuggest::class, $qb->suggest()->term('name', 'field'));
+
+        // Collapse is a special case of the above; it doesn't have an abstract base class for individual parts right
+        // now because 'inner_hits' is the only thing that can be set besides field and concurrency.
+        $this->assertInstanceOf(Collapse\InnerHits::class, $qb->collapse()->inner_hits());
     }
 }