[BUGFIX] Use custom image file extensions for image processing tests

If an integrator removes image file extensions, e.g. "gif", from
$GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'] the whole image
processing test in the install tool fails.

That's because some tests need to run independent of the global
configuration. Therefore the GraphicalFunctions class, which is
used as the image processor, now features a setter. This allows
EXT:install to manually define required image extensions for the
tests, which should not consider the global configuration.

Note: The `convertImageFormatsToJpg` test, which tries to
convert every defined image file extension (based on the
global configuration) to JPG, is not affected by this change.

Resolves: #92958
Releases: master, 10.4
Change-Id: Ic84be73c897f497fedd6b442965edf6fb3ef88c3
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67344
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Martin Kutschker <mkutschker-typo3@yahoo.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Martin Kutschker <mkutschker-typo3@yahoo.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>

typo3/sysext/core/Classes/Imaging/GraphicalFunctions.php

@@ -1192,6 +1192,15 @@ public function getTextScalFactor($conf)
         return $sF;
     }
 
+    /**
+     * @param array $imageFileExt
+     * @internal Only used for ext:install, not part of TYPO3 Core API.
+     */
+    public function setImageFileExt(array $imageFileExt): void
+    {
+        $this->imageFileExt = $imageFileExt;
+    }
+
     /**
      * Renders a regular text and takes care of a possible line break automatically.
      *

typo3/sysext/install/Classes/Controller/EnvironmentController.php

@@ -51,6 +51,8 @@
  */
 class EnvironmentController extends AbstractController
 {
+    private const IMAGE_FILE_EXT = ['gif', 'jpg', 'png', 'tif', 'ai', 'pdf'];
+
     /**
      * @var LateBootService
      */
@@ -911,6 +913,7 @@ protected function initializeImageProcessor(): GraphicalFunctions
         $imageProcessor->filenamePrefix = 'installTool-';
         $imageProcessor->dontCompress = true;
         $imageProcessor->alternativeOutputKey = 'typo3InstallTest';
+        $imageProcessor->setImageFileExt(self::IMAGE_FILE_EXT);
         return $imageProcessor;
     }
 
@@ -1086,10 +1089,10 @@ protected function getImageTestResponse(array $testResult): ResponseInterface
             'success' => true,
         ];
         foreach ($testResult as $resultKey => $value) {
-            if ($resultKey === 'referenceFile') {
+            if ($resultKey === 'referenceFile' && !empty($testResult['referenceFile'])) {
                 $fileExt = end(explode('.', $testResult['referenceFile']));
                 $responseData['referenceFile'] = 'data:image/' . $fileExt . ';base64,' . base64_encode((string)file_get_contents($testResult['referenceFile']));
-            } elseif ($resultKey === 'outputFile') {
+            } elseif ($resultKey === 'outputFile' && !empty($testResult['outputFile'])) {
                 $fileExt = end(explode('.', $testResult['outputFile']));
                 $responseData['outputFile'] = 'data:image/' . $fileExt . ';base64,' . base64_encode((string)file_get_contents($testResult['outputFile']));
             } else {