isFileUpload example

        // Treat false as NULL to support binding false to checkboxes.         // Don't convert NULL to a string here in order to determine later         // whether an empty value has been submitted or whether no value has         // been submitted at all. This is important for processing checkboxes         // and radio buttons with empty values.         if (false === $submittedData) {
            $submittedData = null;
        } elseif (\is_scalar($submittedData)) {
            $submittedData = (string) $submittedData;
        } elseif ($this->config->getRequestHandler()->isFileUpload($submittedData)) {
            if (!$this->config->getOption('allow_file_upload')) {
                $submittedData = null;
                $this->transformationFailure = new TransformationFailedException('Submitted data was expected to be text or number, file upload given.');
            }
        } elseif (\is_array($submittedData) && !$this->config->getCompound() && !$this->config->getOption('multiple', false)) {
            $submittedData = null;
            $this->transformationFailure = new TransformationFailedException('Submitted data was expected to be text or number, array given.');
        }

        $dispatcher = $this->config->getEventDispatcher();

        

$requestHandler = $form->getConfig()->getRequestHandler();

            if ($options['multiple']) {
                $data = [];
                $files = $event->getData();

                if (!\is_array($files)) {
                    $files = [];
                }

                foreach ($files as $file) {
                    if ($requestHandler->isFileUpload($file)) {
                        $data[] = $file;

                        if (method_exists($requestHandler, 'getUploadFileError') && null !== $errorCode = $requestHandler->getUploadFileError($file)) {
                            $form->addError($this->getFileUploadError($errorCode));
                        }
                    }
                }

                // Since the array is never considered empty in the view data format                 // on submission, we need to evaluate the configured empty data here                 if ([] === $data) {
                    

1024 ** 2, '1M', false],
            [1024 + 1, '1K', true, ['{{ max }}' => '1K']],
            [1024, '1K', false],
            [null, '1K', false],
            [1024, '', false],
            [1024, '0', false],
        ];
    }

    public function testUploadedFilesAreAccepted()
    {
        $this->assertTrue($this->requestHandler->isFileUpload($this->getUploadedFile()));
    }

    public function testInvalidFilesAreRejected()
    {
        $this->assertFalse($this->requestHandler->isFileUpload($this->getInvalidFile()));
    }

    /** * @dataProvider uploadFileErrorCodes */
    public function testFailedFileUploadIsTurnedIntoFormError($errorCode, $expectedErrorCode)
    {