recent-topics: Update hash for view to be "#recent".

Updates the hash used for the recent conversations view to be
"#recent" instead of "#recent_topics".

We will need to keep the logic for handling "#recent_topics"
permanently because users potentially have messages from
Welcome Bot with links to that hash.

Including "recent_topics" as a web_public_allowed_hash in
hash_util.js can be changed once self-hosted servers cannot
upgrade directly to Zulip 5.x from the current version.

Fixes #23132.

frontend_tests/node_tests/hashchange.js

@@ -205,6 +205,19 @@ run_test("hash_interactions", ({override}) => {
         [floating_recipient_bar, "update"],
     ]);
 
+    // Test old "#recent_topics" hash redirects to "#recent".
+    recent_topics_ui_shown = false;
+    window.location.hash = "#recent_topics";
+
+    helper.clear_events();
+    $window_stub.trigger("hashchange");
+    assert.equal(recent_topics_ui_shown, true);
+    helper.assert_events([
+        [overlays, "close_for_hash_change"],
+        [message_viewport, "stop_auto_scrolling"],
+    ]);
+    assert.equal(window.location.hash, "#recent");
+
     window.location.hash = "#narrow/stream/Denmark";
 
     helper.clear_events();

static/js/hash_util.js

@@ -272,8 +272,13 @@ export function is_spectator_compatible(hash) {
     // This implementation should agree with the similar function in zerver/lib/narrow.py.
     const web_public_allowed_hashes = [
         "",
-        "narrow", // full #narrow hash handled in narrow.is_spectator_compatible
+        // full #narrow hash handled in narrow.is_spectator_compatible
+        "narrow",
+        // TODO/compatibility: #recent_topics was renamed to #recent
+        // in 2022. We should support the old URL fragment at least
+        // until one cannot directly upgrade from Zulip 5.x.
         "recent_topics",
+        "recent",
         "keyboard-shortcuts",
         "message-formatting",
         "search-operators",

static/js/hashchange.js

@@ -181,6 +181,17 @@ function do_hashchange_normal(from_reload) {
             show_default_view();
             break;
         case "#recent_topics":
+            // The URL for Recent Conversations was changed from
+            // #recent_topics to #recent in 2022. Because pre-change
+            // Welcome Bot messages included links to this URL, we
+            // need to support the "#recent_topics" hash as an alias
+            // for #recent permanently. We show the view and then
+            // replace the current URL hash in a way designed to hide
+            // this detail in the browser's forward/back session history.
+            recent_topics_ui.show();
+            window.location.replace("#recent");
+            break;
+        case "#recent":
             recent_topics_ui.show();
             break;
         case "#all_messages":

static/js/hotkey.js

@@ -819,7 +819,7 @@ export function process_hotkey(e, hotkey) {
             narrow.narrow_to_next_pm_string();
             return true;
         case "open_recent_topics":
-            browser_history.go_to_location("#recent_topics");
+            browser_history.go_to_location("#recent");
             return true;
         case "all_messages":
             browser_history.go_to_location("#all_messages");

static/templates/bookend.hbs

@@ -2,7 +2,7 @@
 <div class="{{#if is_trailing_bookend}}trailing_bookend {{/if}}bookend sub-unsub-message">
     {{#if is_spectator}}
         <span class="recent-topics-link">
-            <a href="#recent_topics">{{t "Browse recent conversations" }}</a>
+            <a href="#recent">{{t "Browse recent conversations" }}</a>
         </span>
     {{else}}
         <span class="stream-status">

static/templates/left_sidebar.hbs

@@ -14,7 +14,7 @@
                 <span class="arrow all-messages-sidebar-menu-icon hidden-for-spectators"><i class="zulip-icon zulip-icon-ellipsis-v-solid" aria-hidden="true"></i></span>
             </li>
             <li class="top_left_recent_topics top_left_row" title="{{t 'Recent conversations' }} (t)">
-                <a href="#recent_topics">
+                <a href="#recent">
                     <span class="filter-icon">
                         <i class="fa fa-clock-o" aria-hidden="true"></i>
                     </span>

zerver/lib/onboarding.py

@@ -154,7 +154,7 @@ def select_welcome_bot_response(human_response_lower: str) -> str:
                 )
                 + "\n\n",
                 _(
-                    "Check out [Recent conversations](#recent_topics) to see what's happening! "
+                    "Check out [Recent conversations](#recent) to see what's happening! "
                     'You can return to this conversation by clicking "Private messages" in the upper left.'
                 ),
             ]

zerver/tests/test_tutorial.py

@@ -98,7 +98,7 @@ class TutorialTests(ZulipTestCase):
             expected_response = (
                 "In Zulip, topics [tell you what a message is about](/help/streams-and-topics). "
                 "They are light-weight subjects, very similar to the subject line of an email.\n\n"
-                "Check out [Recent conversations](#recent_topics) to see what's happening! "
+                "Check out [Recent conversations](#recent) to see what's happening! "
                 'You can return to this conversation by clicking "Private messages" in the upper left.'
             )
             self.assertEqual(most_recent_message(user).content, expected_response)