Add test case

tests/PhpSpreadsheetTests/Reader/Xls/XlsBugPr3734Test.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Reader\Xls;
+
+use PHPUnit\Framework\ExpectationFailedException;
+use PHPUnit\Framework\TestCase;
+use PhpOffice\PhpSpreadsheet\IOFactory;
+use SplFileInfo;
+
+class XlsBugPr3734Test extends TestCase
+{
+    /**
+     * Test XLS file including data with missing fonts?
+     */
+    public function testXlsFileWithNoFontIndex(): void
+    {
+        $fileName = dirname(__DIR__, 3) . '/data/Reader/XLS/bug-pr-3734.xls';
+        $file = new SplFileInfo($fileName);
+
+        IOFactory::load($file);
+
+        // If no error occurs on load, test is passed!
+        self::assertTrue(true);
+    }
+}