matcher.php

<?php
    function it_decodes_a_json_export_into_a_collection_of_bookmarks()
    {
        $result = $this->parse(__DIR__ . '/../pinboard_export.json');

        $result->shouldHaveType(Collection::class);
        $result->shouldHaveCount(3);
        $result->shouldContainOnlyInstancesOf(Bookmark::class);
    }

    public function getMatchers()
    {
        return [
            'containOnlyInstancesOf' => function($collection, $className) {
                foreach ($collection as $item) {
                    if (!$item instanceof $className){
                        return false;
                    }
                }

                return true;
            }
        ];
    }