Creating a unit test for a Twig template

Published on 2021-07-02 • Modified on 2021-07-02

In this snippet, we see how to create a unit test for a Twig template. This template contains a simple if tag like this:

{% if case == 1 %}This is case 1! 🎉{% else %}This is NOT case 1.{% endif %}

We use a test provider; the two first cases are the nominal cases, the third one checks that an exception is raised because the case variable isn't passed to the template. We have an error when using the Twig strict mode that is enabled with the strict_variables parameter.

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<?php

declare(strict_types=1);

namespace App\Tests\Integration\Twig;

use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
use Twig\Environment;
use Twig\Error\RuntimeError;

final class Snippet152Test extends KernelTestCase
{
    private Environment $twig;

    protected function setUp(): void
    {
        $this->twig = self::getContainer()->get(Environment::class);
    }

    /**
     * @return iterable<string, array{0: array<string,mixed>, 1: string, 2: bool}>
     */
    public function snippet1527Provider(): iterable
    {
        yield 'case 1, nomimal case' => [['case' => 1], 'this is case 1', false];
        yield 'case 2, nomimal case' => [['case' => 2], 'this is NOT case 1', false];
        yield 'case 3, wrong type' => [['case' => 'c'], 'this is NOT case 1', false]; // no strict type at the Twig level
        yield 'exception case' => [['case_not_provided' => 99], 'RuntimeError!', true];
    }

    /**
     * @param array<string, mixed> $context
     *
     * @dataProvider snippet1527Provider
     */
    public function testSnippet152(array $context, string $needle, bool $expectException): void
    {
        if ($expectException) {
            $this->expectException(RuntimeError::class);
        }

        $haystack = $this->twig->render('snippet/code/_152_demo.html.twig', $context);
        self::assertStringContainsStringIgnoringCase($needle, $haystack);
    }
}

This is case 1! 🎉

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