FIX: _uploadDropTargetOptions is now public (#29246)

Chat was using a private function which has now been made public.

This commit also adds a test for this codepath.

plugins/chat/assets/javascripts/discourse/components/chat-composer-uploads.js

@@ -80,7 +80,7 @@ export default class ChatComposerUploads extends Component.extend(
     this._triggerUploadsChanged();
   }
 
-  _uploadDropTargetOptions() {
+  uploadDropTargetOptions() {
     return {
       target: this.uploadDropZone || document.body,
     };

plugins/chat/spec/system/uploads_spec.rb

@@ -17,6 +17,29 @@ describe "Uploading files in chat messages", type: :system do
       sign_in(current_user)
     end
 
+    it "allows to drag files to start upload" do
+      chat.visit_channel(channel_1)
+
+      # Define the JavaScript to simulate dragging an external image
+      page.execute_script(<<-JS)
+        const target = document.querySelector('.chat-channel');
+        const dataTransfer = new DataTransfer();
+        const file = new File(['dummy content'], 'test-image.png', { type: 'image/png' });
+
+        dataTransfer.items.add(file);
+
+        const dragEnterEvent = new DragEvent('dragenter', { dataTransfer: dataTransfer });
+        target.dispatchEvent(dragEnterEvent);
+
+        const dragOverEvent = new DragEvent('dragover', { dataTransfer: dataTransfer });
+        target.dispatchEvent(dragOverEvent);
+      JS
+
+      expect(find(".chat-upload-drop-zone__text__title")).to have_content(
+        I18n.t("js.chat.upload_to_channel", { title: channel_1.title }),
+      )
+    end
+
     it "allows uploading a single file" do
       chat.visit_channel(channel_1)
       file_path = file_from_fixtures("logo.png", "images").path