Trait to detect repeated queries (i.e. N+1 problem) inside unit tests

DetectRepeatedQueries.php

<?php

namespace Tests;

use Illuminate\Support\Facades\DB;

trait DetectRepeatedQueries
{
    public function enableQueryLog()
    {
        DB::enableQueryLog();
    }

    /**
     * Assert there are not repeated queries being executed.
     */
    public function assertNotRepeatedQueries()
    {
        $queries = array_column(DB::getQueryLog(), 'query');

        $selects = array_filter($queries, function ($query) {
            return strpos($query, 'select') === 0;
        });

        $selects = array_count_values($selects);

        foreach ($selects as $select => $amount) {
            $this->assertEquals(
                1, $amount, "The following SELECT was executed $amount times:\n\n $select"
            );
        }
    }

    public function flushQueryLog()
    {
        DB::flushQueryLog();
    }
}

@browner12 yes, to detect possible N+1 problems in your application, you can use this in your tests like so:

        $this->enableQueryLog();
        
        $this->get('posts');

        $this->assertNotRepeatedQueries();

So for example if you forgot to use eager loading in your posts list, and you are loading the same category 10 times, the trait will warn you :D

Great. Thanks for sharing.
By the way Laravel Debugbar also shows duplicated queries. But only number of them without showing exact repeated SQL.

Is this comparing query with bindings or it considers query as repeat even if it has other params?

@decadence: even if they have difference parameters. Because you can be fetching 37 different teams associated to users, they all will have different IDs but the query is the same and could be fixed with eager loading. (Sorry for the extremely late response).