Snapshot testing in Symfony

SnapshotTrait.php

<?php

namespace Tests;

use Symfony\Component\VarDumper\Test\VarDumperTestTrait;

trait SnapshotTrait
{
    use VarDumperTestTrait;

    private function assertSnapshot($name, $content)
    {
        $this->snapshotIfNeeded($name, $content);
        $this->compareSnapshot($name, $content);
    }

    private function snapshotIfNeeded($name, $content)
    {
        $snapshotFile = $this->getSnapshotFile($name);

        if (!file_exists($snapshotFile) || getenv('UPDATE_SNAPSHOTS') === '1') {
            file_put_contents($snapshotFile, $this->getDump($content));
        }
    }

    private function compareSnapshot($name, $content)
    {
        $this->assertDumpEquals(file_get_contents($this->getSnapshotFile($name)), $content);
    }

    private function getSnapshotFile($name)
    {
        return __DIR__.'/snapshots/'.$name.'.txt';
    }
}