Add top_level_only parameter to Groups::all method (#684)

This PR adds a `top_level_only` parameter to the `GitLab\Api\Groups::all` method, which limits the results to top level groups, excluding all subgroups.

Because this parameter is not available for the `subgroups` method, it was necessary to split up the `getGroupSearchResolver` method, which was called by both the `all` and the `subgroups` method.

Author: aadmathijssen

src/Api/Groups.php

@@ -30,6 +30,7 @@ class Groups extends AbstractApi
      *     @var bool   $statistics       include group statistics (admins only)
      *     @var bool   $owned            limit by groups owned by the current user
      *     @var int    $min_access_level limit by groups in which the current user has at least this access level
+     *     @var bool   $top_level_only   limit to top level groups, excluding all subgroups
      * }
      *
      * @return mixed
@@ -314,7 +315,7 @@ public function projects($id, array $parameters = [])
      */
     public function subgroups($group_id, array $parameters = [])
     {
-        $resolver = $this->getGroupSearchResolver();
+        $resolver = $this->getSubgroupSearchResolver();
 
         return $this->get('groups/'.self::encodePath($group_id).'/subgroups', $resolver->resolve($parameters));
     }
@@ -500,6 +501,24 @@ public function packages($group_id, array $parameters = [])
      * @return OptionsResolver
      */
     private function getGroupSearchResolver()
+    {
+        $resolver = $this->getSubgroupSearchResolver();
+        $booleanNormalizer = function (Options $resolver, $value): string {
+            return $value ? 'true' : 'false';
+        };
+
+        $resolver->setDefined('top_level_only')
+            ->setAllowedTypes('top_level_only', 'bool')
+            ->setNormalizer('top_level_only', $booleanNormalizer)
+        ;
+
+        return $resolver;
+    }
+
+    /**
+     * @return OptionsResolver
+     */
+    private function getSubgroupSearchResolver()
     {
         $resolver = $this->createOptionsResolver();
         $booleanNormalizer = function (Options $resolver, $value): string {

tests/Api/GroupsTest.php

@@ -58,6 +58,26 @@ public function shouldGetAllGroupsWithBooleanParam(): void
         $this->assertEquals($expectedArray, $api->all(['all_available' => false]));
     }
 
+    /**
+     * @test
+     */
+    public function shouldGetAllTopLevelGroupsWithoutSubgroups(): void
+    {
+        $expectedArray = [
+            ['id' => 1, 'name' => 'A group'],
+            ['id' => 2, 'name' => 'Another group'],
+        ];
+
+        $api = $this->getApiMock();
+        $api->expects($this->once())
+            ->method('get')
+            ->with('groups', ['top_level_only' => 'true'])
+            ->will($this->returnValue($expectedArray))
+        ;
+
+        $this->assertEquals($expectedArray, $api->all(['top_level_only' => true]));
+    }
+
     /**
      * @test
      */