MQE-522: Fixed warnings for length has to be greater than zero for substr_count() when using php < 7.1.

Author: jilu1

src/Magento/FunctionalTestingFramework/Util/TestGenerator.php

@@ -980,9 +980,13 @@ private function processQuoteBreaks($match, $argument, $replacement)
         $beforeIndex = strpos($outputArg, $match) - 1;
         $afterIndex = $beforeIndex + strlen($match) + 1;
 
+        $quoteBefore = false;
         // Determine if there is a " before/after the $match, and if there is only one " before/after match.
-        $quoteBefore = $argument[$beforeIndex] == '"' && substr_count($argument, '"', 0, $beforeIndex)<1;
-        $quoteAfter = $argument[$afterIndex] == '"' && substr_count($argument, '"', $afterIndex+1)<1;
+        if ($beforeIndex == 0
+            || ($argument[$beforeIndex] == '"' && substr_count($argument, '"', 0, $beforeIndex) < 1)) {
+            $quoteBefore = true;
+        }
+        $quoteAfter = $argument[$afterIndex] == '"' && substr_count($argument, '"', $afterIndex+1) < 1;
 
         //Remove quotes at either end of argument if they aren't necessary. Add double-quote concatenation if needed.
         if ($quoteBefore) {