Extract remaining Excel function unit tests into separate test classe…

…s for each function (#1817)

* Extract remaining Financial function unit tests into separate test classes for each function

This makes it easier to manage unit tests if they are individual files rather than all in a single file

It also provides a stepping stone toward making it easier to test Excel functions when Excel errors no longer return a string, but an actual Excel exception that can be handled more cleanly

src/PhpSpreadsheet/Shared/OLE.php

@@ -227,7 +227,8 @@ public function getStream($blockIdOrPps)
         // in OLE_ChainedBlockStream::stream_open().
         // Object is removed from self::$instances in OLE_Stream::close().
         $GLOBALS['_OLE_INSTANCES'][] = $this;
-        $instanceId = end(array_keys($GLOBALS['_OLE_INSTANCES']));
+        $keys = array_keys($GLOBALS['_OLE_INSTANCES']);
+        $instanceId = end($keys);
 
         $path = 'ole-chainedblockstream://oleInstanceId=' . $instanceId;
         if ($blockIdOrPps instanceof OLE\PPS) {

src/PhpSpreadsheet/Worksheet/AutoFilter.php

@@ -595,7 +595,9 @@ private function calculateTopTenValue($columnID, $startRow, $endRow, $ruleType,
             sort($dataValues);
         }
 
-        return array_pop(array_slice($dataValues, 0, $ruleValue));
+        $slice = array_slice($dataValues, 0, $ruleValue);
+
+        return array_pop($slice);
     }
 
     /**