[GITEA] convert feed items' titles to plain text

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

(cherry picked from commit 35b962e6313df748e8855b4dfbf748f095ea1003)
(cherry picked from commit 1004e35b84a4a0deae999cb8a4c2924b85b47c8b)
(cherry picked from commit af51dd594db229f7a986325a6070d33782d85d28)
(cherry picked from commit ef10fae29607533db3616a23043cc0f2fc2dc71a)
(cherry picked from commit ff8027ed1b0a1274b7b6e4840e31e2ad4d18b159)
(cherry picked from commit 2540ff52ef)

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>")
+		})
+	})
+}