--- /dev/null
+--TEST--
+header params rfc5987 regression
+--SKIPIF--
+<?php
+include "skipif.inc";
+?>
+--FILE--
+<?php
+echo "Test\n";
+$p = new http\Params(["attachment"=>["filename"=>"foo.bar"]]);
+var_dump($p->params);
+var_dump((string)$p);
+?>
+===DONE===
+--EXPECT--
+Test
+array(1) {
+ ["attachment"]=>
+ array(1) {
+ ["filename"]=>
+ string(7) "foo.bar"
+ }
+}
+string(27) "attachment;filename=foo.bar"
+===DONE===