Quick implementation of a lock via file

LockFile.php

<?php declare(strict_types=1);

final class LockFile
{
    private const LOCK_EXTENSION = '.lock';
    private readonly string $fileName;

    public function __construct(string $fileName, private readonly int $duration)
    {
        $this->fileName = $fileName . self::LOCK_EXTENSION;
    }

    public function createLock(): bool
    {
        if ($this->isLocked()) {
            return false;
        }

        return touch($this->fileName);
    }

    public function isLocked(): bool
    {
        if (!is_file($this->fileName)) {
            return false;
        }

        if ($this->isExpired()) {
            return false;
        }

        return true;
    }

    public function releaseLock(): bool
    {
        if (is_file($this->fileName)) {
            return unlink($this->fileName);
        }

        return false;
    }

    private function isExpired(): bool
    {
        $fileAge = time() - filemtime($this->fileName);

        return $fileAge > $this->duration;
    }
}

LockFileTest.php

<?php declare(strict_types=1);

use PHPUnit\Framework\TestCase;

final class LockFileTest extends TestCase
{
    /** @test */
    public function it_should_create_a_lock_file(): void
    {
        $lockFile = new LockFile('/tmp/foo', 10);

        self::assertTrue($lockFile->createLock());
        self::assertFileExists('/tmp/foo.lock');
    }

    /** @test */
    public function it_should_remove_a_lock_file(): void
    {
        $lockFile = new LockFile('/tmp/foo', 10);

        self::assertTrue($lockFile->createLock());
        self::assertFileExists('/tmp/foo.lock');

        self::assertTrue($lockFile->releaseLock());
        self::assertFileDoesNotExist('/tmp/foo.lock');
    }

    /** @test */
    public function it_should_return_false_if_a_lock_file_could_not_be_created(): void
    {
        $lockFile = new LockFile('/tmp/foo', 10);

        self::assertTrue($lockFile->createLock());
        self::assertFalse($lockFile->createLock());
    }

    /** @test */
    public function it_should_return_false_if_a_lock_file_could_not_be_removed(): void
    {
        $lockFile = new LockFile('/tmp/foo', 10);

        self::assertFalse($lockFile->releaseLock());
    }

    /** @test */
    public function it_should_show_if_a_lock_file_is_active(): void
    {
        $lockFile = new LockFile('/tmp/foo', 0);

        self::assertFalse($lockFile->isLocked());

        self::assertTrue($lockFile->createLock());
        self::assertTrue($lockFile->isLocked());

        sleep(1);
        self::assertFalse($lockFile->isLocked());
    }

    public function tearDown(): void
    {
        @unlink('/tmp/foo.lock');
    }
}