add test for validation

tests/validation_limiting_to_a_single_or_range_cell.phpt

@@ -0,0 +1,25 @@
+--TEST--
+Check for vtiful presence
+--SKIPIF--
+<?php if (!extension_loaded("xlswriter")) print "skip"; ?>
+--FILE--
+<?php
+$config = ['path' => './tests'];
+
+$validation = new \Vtiful\Kernel\Validation();
+$validation->validationType(\Vtiful\Kernel\Validation::TYPE_LIST)
+    ->valueList(['wjx', 'viest'])
+    ->valueList(['wjx', 'viest']);
+
+$excel    = new \Vtiful\Kernel\Excel($config);
+$filePath = $excel->fileName('tutorial.xlsx')
+    ->validation('A1', $validation->toResource())
+    ->output();
+
+var_dump($validation, $filePath);
+?>
+--EXPECT--
+object(Vtiful\Kernel\Validation)#1 (0) {
+}
+string(21) "./tests/tutorial.xlsx"
+