Add a test for Bug 77024

Author: duncan3dc

ext/spl/tests/bug77024.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #77024 SplFileObject::__toString() may return array
+--FILE--
+<?php
+
+$file = new SplTempFileObject;
+$file->fputcsv(['foo', 'bar', 'baz']);
+$file->rewind();
+$file->setFlags(SplFileObject::READ_CSV);
+echo $file . "\n";
+
+$tmp = tempnam(sys_get_temp_dir(), "php-tests-");
+file_put_contents($tmp, "line1\nline2\nline3\n");
+$file = new SplFileObject($tmp);
+$file->rewind();
+echo $file . "\n";
+unset($file);
+unlink($tmp);
+
+?>
+--EXPECTF--
+foo,bar,baz
+
+line1