net.http: fix http.delete() checking (#20131)

Author: felipensp

vlib/net/http/header.v

@@ -469,8 +469,8 @@ pub fn (mut h Header) delete(key CommonHeader) {
 
 // delete_custom deletes all values for a custom header key.
 pub fn (mut h Header) delete_custom(key string) {
-	for i, kv in h.data {
-		if kv.key == key {
+	for i := 0; i < h.cur_pos; i++ {
+		if h.data[i].key == key {
 			h.data[i] = HeaderKV{key, ''}
 		}
 	}

vlib/net/http/header_test.v

@@ -79,6 +79,13 @@ fn test_header_delete_not_existing() {
 	// assert h.keys.len == 0
 }
 
+fn test_delete_header() {
+	mut r := new_request(.get, '', '')
+	r.header.set(.authorization, 'foo')
+	r.header.delete(.authorization)
+	assert r.header.get(.authorization)! == ''
+}
+
 fn test_custom_header() {
 	mut h := new_header()
 	h.add_custom('AbC', 'dEf')!