class FileTest extends PHPUnit_Framework_TestCase { private $filename; public function setUp() { $this->filename = 'tempfile.txt'; file_put_contents($this->filename, 'Hello, World!'); } public function tearDown() { if (file_exists($this->filename)) { unlink($this->filename); } } public function testFileExists() { $this->assertFileExists($this->filename); } }In this example, `setUp()` is used to create a temporary file, which is then used in the `testFileExists()` method. `tearDown()` is used to delete the temporary file after the test has run. This code example utilizes the PHPUnit package library.