FIX: Poll: Show gear button only when there is more than one dropdown item (#27775)

During migration of Poll plugin from widget basis to glimmer, some functionality was inadvertently dropped:

- A single button should appear instead of the dropdown menu when there is only one valid "poll admin" action
- No button should appear when there are no valid "poll admin" actions for current user

This PR restores the original behaviour and adds test coverage (that didn't exist prior to migration, partly why it wasn't caught earlier)

relates to #27204

related meta topic:  https://meta.discourse.org/t/what-is-the-gear-button-under-the-poll-for/315477/2

plugins/poll/assets/javascripts/discourse/components/poll-buttons-dropdown.gjs

@@ -1,6 +1,6 @@
 import Component from "@glimmer/component";
 import { fn } from "@ember/helper";
-import { action } from "@ember/object";
+import { action, get } from "@ember/object";
 import { inject as service } from "@ember/service";
 import DButton from "discourse/components/d-button";
 import DropdownMenu from "discourse/components/dropdown-menu";
@@ -107,6 +107,7 @@ export default class PollButtonsDropdownComponent extends Component {
 
   <template>
     <div class="poll-buttons-dropdown">
+      {{#if this.showDropdown}}
         <DMenu class="widget-dropdown-header">
           <:trigger>
             {{icon "cog"}}
@@ -127,6 +128,17 @@ export default class PollButtonsDropdownComponent extends Component {
             </DropdownMenu>
           </:content>
         </DMenu>
+      {{else if this.showDropdownAsButton}}
+        <DButton
+          class="widget-button {{get this.getDropdownContent '0.className'}}"
+          @icon={{get this.getDropdownContent "0.icon"}}
+          @label={{get this.getDropdownContent "0.label"}}
+          @action={{fn
+            this.dropDownClick
+            (get this.getDropdownContent "0.action")
+          }}
+        />
+      {{/if}}
     </div>
   </template>
 }

plugins/poll/test/javascripts/component/poll-buttons-dropdown-test.js

@@ -9,9 +9,13 @@ module("Poll | Component | poll-buttons-dropdown", function (hooks) {
   setupRenderingTest(hooks);
 
   test("Renders a clickable dropdown menu with a close option", async function (assert) {
+    this.siteSettings.data_explorer_enabled = true;
+    this.siteSettings.poll_export_data_explorer_query_id = 18;
+    this.currentUser.setProperties({ admin: true });
+
     this.setProperties({
-      closed: false,
-      voters: [],
+      closed: true,
+      voters: 3,
       isStaff: true,
       isMe: false,
       topicArchived: false,
@@ -33,12 +37,74 @@ module("Poll | Component | poll-buttons-dropdown", function (hooks) {
 
     await click(".widget-dropdown-header");
 
-    assert.strictEqual(count("li.dropdown-menu__item"), 1);
+    assert.strictEqual(count("li.dropdown-menu__item"), 2);
 
     assert.strictEqual(
       query("li.dropdown-menu__item span").textContent.trim(),
-      I18n.t("poll.close.label"),
+      I18n.t("poll.export-results.label"),
+      "displays the poll Export action"
+    );
+  });
+
+  test("Renders a single button when there is only one authorised action", async function (assert) {
+    this.setProperties({
+      closed: false,
+      voters: 2,
+      isStaff: false,
+      isMe: false,
+      topicArchived: false,
+      groupableUserFields: ["stuff"],
+      isAutomaticallyClosed: false,
+      dropDownClick: () => {},
+    });
+
+    await render(hbs`<PollButtonsDropdown
+      @closed={{this.closed}}
+      @voters={{this.voters}}
+      @isStaff={{this.isStaff}}
+      @isMe={{this.isMe}}
+      @topicArchived={{this.topicArchived}}
+      @groupableUserFields={{this.groupableUserFields}}
+      @isAutomaticallyClosed={{this.isAutomaticallyClosed}}
+      @dropDownClick={{this.dropDownClick}}
+    />`);
+
+    assert.strictEqual(count(".widget-dropdown-header"), 0);
+
+    assert.strictEqual(count("button.widget-button"), 1);
+
+    assert.strictEqual(
+      query("button.widget-button span.d-button-label").textContent.trim(),
+      I18n.t("poll.breakdown.breakdown"),
       "displays the poll Close action"
     );
   });
+
+  test("Doesn't render a button when user has no authorised actions", async function (assert) {
+    this.setProperties({
+      closed: false,
+      voters: 0,
+      isStaff: false,
+      isMe: false,
+      topicArchived: false,
+      groupableUserFields: [],
+      isAutomaticallyClosed: false,
+      dropDownClick: () => {},
+    });
+
+    await render(hbs`<PollButtonsDropdown
+      @closed={{this.closed}}
+      @voters={{this.voters}}
+      @isStaff={{this.isStaff}}
+      @isMe={{this.isMe}}
+      @topicArchived={{this.topicArchived}}
+      @groupableUserFields={{this.groupableUserFields}}
+      @isAutomaticallyClosed={{this.isAutomaticallyClosed}}
+      @dropDownClick={{this.dropDownClick}}
+    />`);
+
+    assert.strictEqual(count(".widget-dropdown-header"), 0);
+
+    assert.strictEqual(count("button.widget-button"), 0);
+  });
 });