[GITEA] convert feed items' titles to plain text

Refs: https://codeberg.org/forgejo/forgejo/pulls/1595

(cherry picked from commit 35b962e631)
(cherry picked from commit 1004e35b84)
(cherry picked from commit af51dd594d)
(cherry picked from commit 7fb66b4556)
(cherry picked from commit 0c409950f1)
(cherry picked from commit edf1cb72b4)
(cherry picked from commit d1e5d9d664)

routers/web/feed/convert.go

@@ -21,6 +21,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 
 	"github.com/gorilla/feeds"
+	"github.com/jaytaylor/html2text"
 )
 
 func toBranchLink(ctx *context.Context, act *activities_model.Action) string {
@@ -239,8 +240,15 @@ func feedActionsToFeedItems(ctx *context.Context, actions activities_model.Actio
 			content = desc
 		}
 
+		// It's a common practice for feed generators to use plain text titles.
+		// See https://codeberg.org/forgejo/forgejo/pulls/1595
+		plainTitle, err := html2text.FromString(title, html2text.Options{OmitLinks: true})
+		if err != nil {
+			return nil, err
+		}
+
 		items = append(items, &feeds.Item{
-			Title:       title,
+			Title:       plainTitle,
 			Link:        link,
 			Description: desc,
 			Author: &feeds.Author{

tests/integration/api_feed_plain_text_titles_test.go

@@ -0,0 +1,40 @@
+// Copyright 2023 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"net/http"
+	"testing"
+
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFeedPlainTextTitles(t *testing.T) {
+	// This test verifies that items' titles in feeds are generated as plain text.
+	// See https://codeberg.org/forgejo/forgejo/pulls/1595
+
+	t.Run("Feed plain text titles", func(t *testing.T) {
+		t.Run("Atom", func(t *testing.T) {
+			defer tests.PrepareTestEnv(t)()
+
+			req := NewRequest(t, "GET", "/user2/repo1.atom")
+			resp := MakeRequest(t, req, http.StatusOK)
+
+			data := resp.Body.String()
+			assert.Contains(t, data, "<title>the_1-user.with.all.allowedChars closed issue user2/repo1#4</title>")
+		})
+
+		t.Run("RSS", func(t *testing.T) {
+			defer tests.PrepareTestEnv(t)()
+
+			req := NewRequest(t, "GET", "/user2/repo1.rss")
+			resp := MakeRequest(t, req, http.StatusOK)
+
+			data := resp.Body.String()
+			assert.Contains(t, data, "<title>the_1-user.with.all.allowedChars closed issue user2/repo1#4</title>")
+		})
+	})
+}