[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)

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>")
+		})
+	})
+}