Test if UConverter Exists Without Autoload

Fix PHPOffice#2982. That issue is actually closed, but it did expose a problem. Our test environments all enable php-intl, but that extension isn't a formal requirement for PhpSpreadsheet. Perhaps it ought to be. Nevertheless ...

Using UConverter for string translation solved some problems for us. However, it is only available when php-intl is enabled. The code tests if it exists before using it, so no big deal ... except it seems likely that the people reporting the issue not only did not have php-intl, but they do have their own autoloader which issues an exception when the class isn't found. The test for existence of UConverter defaulted to attempting to autoload it if not found. So, on a system without php-intl but with a custom autoloader, there is a problem. Code is changed to suppress autoload when testing UConverter existence.

Pending this fix, the workaround for this issue is to enable php-intl.

src/PhpSpreadsheet/Shared/StringHelper.php

@@ -334,7 +334,7 @@ public static function controlCharacterPHP2OOXML($textValue)
     public static function sanitizeUTF8(string $textValue): string
     {
         $textValue = str_replace(["\xef\xbf\xbe", "\xef\xbf\xbf"], "\xef\xbf\xbd", $textValue);
-        if (class_exists(UConverter::class)) {
+        if (class_exists(UConverter::class, false)) {
             $returnValue = UConverter::transcode($textValue, 'UTF-8', 'UTF-8');
             if ($returnValue !== false) {
                 return $returnValue;

tests/PhpSpreadsheetTests/Shared/StringHelperInvalidCharTest.php

@@ -2,6 +2,7 @@
 
 namespace PhpOffice\PhpSpreadsheetTests\Shared;
 
+use Exception as Except;
 use PhpOffice\PhpSpreadsheet\Shared\StringHelper;
 use PhpOffice\PhpSpreadsheet\Spreadsheet;
 use PHPUnit\Framework\TestCase;
@@ -12,13 +13,14 @@ public function testInvalidChar(): void
     {
         $spreadsheet = new Spreadsheet();
         $sheet = $spreadsheet->getActiveSheet();
-        $substitution = '�';
+        $substitution = class_exists('UConverter', false) ? '�' : '?';
+        $substitution2 = '�';
         $array = [
             ['Normal string', 'Hello', 'Hello'],
             ['integer', 2, 2],
             ['float', 2.1, 2.1],
             ['boolean true', true, true],
-            ['illegal FFFE/FFFF', "H\xef\xbf\xbe\xef\xbf\xbfello", "H{$substitution}{$substitution}ello"],
+            ['illegal FFFE/FFFF', "H\xef\xbf\xbe\xef\xbf\xbfello", "H{$substitution2}{$substitution2}ello"],
             ['illegal character', "H\xef\x00\x00ello", "H{$substitution}\x00\x00ello"],
             ['overlong character', "H\xc0\xa0ello", "H{$substitution}{$substitution}ello"],
             ['Osmanya as single character', "H\xf0\x90\x90\x80ello", 'H𐐀ello'],
@@ -41,4 +43,38 @@ public function testInvalidChar(): void
             );
         }
     }
+
+    public function fakespl(string $name): void
+    {
+        if (strlen($name) > 0) {
+            throw new Except("$name not found");
+        }
+    }
+
+    public function testClassNotFound(): void
+    {
+        // see issue 2982.
+        // This test will work all the time, but it is valuable
+        //     only if php-intl not available
+        //     and a user-supplied autoloader can issue exception.
+        /** @var callable */
+        $fakespl = [$this, 'fakespl'];
+        spl_autoload_register($fakespl);
+
+        try {
+            self::assertFalse(class_exists('abc123xyz'));
+            self::fail('Expected exception here');
+        } catch (Except $e) {
+            // Nothing to do here
+        }
+
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $sheet->setCellValue('A1', 'Hello World !');
+
+        $spreadsheet->disconnectWorksheets();
+
+        spl_autoload_unregister($fakespl);
+        self::assertFalse(class_exists('abc123wxyz'));
+    }
 }