Tests

app/assets/javascripts/discourse/app/lib/plugin-api.js

@@ -2125,15 +2125,15 @@ class PluginApi {
    * Support for setting a Sidebar panel.
    */
   setSidebarPanel(name) {
-    this._lookupContainer("service:sidebar-state").setPanel(name);
+    this._lookupContainer("service:sidebar-state")?.setPanel(name);
   }
 
   /**
    * EXPERIMENTAL. Do not use.
    * Set combined sidebar section mode. In this mode, sections from all panels are displayed together.
    */
   setCombinedSidebarMode() {
-    this._lookupContainer("service:sidebar-state").setCombinedMode();
+    this._lookupContainer("service:sidebar-state")?.setCombinedMode();
   }
 
   /**
@@ -2157,7 +2157,7 @@ class PluginApi {
    * Hide sidebar switch panels buttons in separated mode.
    */
   hideSidebarSwitchPanelButtons() {
-    this._lookupContainer("service:sidebar-state").hideSwitchPanelButtons();
+    this._lookupContainer("service:sidebar-state")?.hideSwitchPanelButtons();
   }
 
   /**

plugins/chat/test/javascripts/acceptance/mentions-test.js

@@ -0,0 +1,91 @@
+import { acceptance } from "discourse/tests/helpers/qunit-helpers";
+import { test } from "qunit";
+import { fillIn, visit } from "@ember/test-helpers";
+import pretender, { response } from "discourse/tests/helpers/create-pretender";
+
+acceptance("Chat | Mentions", function (needs) {
+  const channelId = 1;
+  const actingUser = {
+    id: 1,
+    username: "acting_user",
+  };
+  const channel = {
+    id: channelId,
+    chatable_id: 1,
+    chatable_type: "Category",
+    meta: { message_bus_last_ids: {}, can_delete_self: true },
+    current_user_membership: { following: true },
+    chatable: { id: 1 },
+  };
+
+  needs.settings({ chat_enabled: true });
+
+  needs.user({
+    ...actingUser,
+    has_chat_enabled: true,
+    chat_channels: {
+      public_channels: [channel],
+      direct_message_channels: [],
+      meta: { message_bus_last_ids: {} },
+      tracking: {},
+    },
+  });
+
+  needs.hooks.beforeEach(function () {
+    pretender.post(`/chat/drafts`, () => response({}));
+    pretender.get(`/chat/api/channels/${channelId}/messages`, () =>
+      response({
+        messages: [],
+        meta: {
+          can_load_more_future: false,
+        },
+      })
+    );
+    pretender.get("/chat/api/mentions/groups.json", () =>
+      response({
+        unreachable: [],
+        over_members_limit: [],
+        invalid: ["and"],
+      })
+    );
+  });
+
+  test("shows warning when mention limit exceeded", async function (assert) {
+    this.siteSettings.max_mentions_per_chat_message = 2;
+
+    await visit(`/chat/c/-/${channelId}`);
+    await fillIn(".chat-composer__input", `Hey @user1 @user2 @user3`);
+
+    assert.dom(".chat-mention-warnings").exists();
+  });
+
+  test("ignores duplicates when counting mentions", async function (assert) {
+    this.siteSettings.max_mentions_per_chat_message = 2;
+
+    await visit(`/chat/c/-/${channelId}`);
+    const mention = `@user1`;
+    await fillIn(
+      ".chat-composer__input",
+      `Hey ${mention} ${mention} ${mention}`
+    );
+
+    assert.dom(".chat-mention-warnings").doesNotExist();
+  });
+
+  test("doesn't consider code-blocks when counting mentions", async function (assert) {
+    this.siteSettings.max_mentions_per_chat_message = 2;
+
+    await visit(`/chat/c/-/${channelId}`);
+    // since @bar is inside a code-block it shouldn't be considered a mention
+    const message = `Hey @user1 @user2
+    \`\`\`
+      def foo
+        @bar = true
+      end
+    \`\`\`
+    `;
+    await fillIn(".chat-composer__input", message);
+
+    assert.dom(".chat-mention-warnings").doesNotExist();
+  });
+});