FIX: ensures event serializer has tags info (#34801)

This was preventing the `map_events_to_color` site setting to work
correctly given we couldn't match on tag slug as it was not present.

This commit adds system specs and removes the js test as it was
misleading and incorrectly passing due to the fixture which couldn't
catch the issue in the serializer.

plugins/discourse-calendar/app/serializers/discourse_post_event/basic_event_serializer.rb

@@ -24,10 +24,15 @@ module DiscoursePostEvent
         id: object.post.id,
         post_number: object.post.post_number,
         url: object.post.url,
-        topic: {
-          id: object.post.topic.id,
-          title: object.post.topic.title,
-        },
+        category_slug:
+          (
+            if object.post.topic && object.post.topic.category
+              object.post.topic.category.slug_for_url
+            else
+              ""
+            end
+          ),
+        topic: TopicListItemSerializer.new(object.post.topic, scope:, root: false).as_json,
       }
     end
 

plugins/discourse-calendar/assets/javascripts/discourse/components/category-calendar.gjs

@@ -122,7 +122,7 @@ export default class CategoryCalendar extends Component {
       if (!backgroundColor) {
         const categoryColorFromMap = this.tagsColorsMap.find(
           (entry) =>
-            entry.type === "category" && entry.slug === post.topic.category_slug
+            entry.type === "category" && entry.slug === post.category_slug
         )?.color;
         backgroundColor =
           categoryColorFromMap || `#${Category.findById(categoryId)?.color}`;

plugins/discourse-calendar/assets/javascripts/discourse/components/upcoming-events-calendar.gjs

@@ -75,7 +75,7 @@ export default class UpcomingEventsCalendar extends Component {
       if (!backgroundColor) {
         const categoryColorEntry = tagsColorsMap.find(
           (entry) =>
-            entry.type === "category" && entry.slug === post.topic.category_slug
+            entry.type === "category" && entry.slug === post.category_slug
         );
         backgroundColor = categoryColorEntry?.color;
       }

plugins/discourse-calendar/spec/models/discourse_post_event/event_spec.rb

@@ -683,7 +683,11 @@ describe DiscoursePostEvent::Event do
 
       it "basic serializer handles expired recurring events correctly" do
         serializer =
-          DiscoursePostEvent::BasicEventSerializer.new(expired_recurring_event, root: false)
+          DiscoursePostEvent::BasicEventSerializer.new(
+            expired_recurring_event,
+            root: false,
+            scope: Guardian.new,
+          )
         json = JSON.parse(serializer.to_json)
 
         expect(json["starts_at"]).to be_nil

plugins/discourse-calendar/spec/system/upcoming_events_spec.rb

@@ -536,4 +536,47 @@ describe "Upcoming Events", type: :system do
       end
     end
   end
+
+  context "with tag color", time: Time.utc(2025, 6, 2, 19, 00) do
+    before do
+      SiteSetting.map_events_to_color = [
+        { type: "tag", color: "rgb(231, 76, 60)", slug: "awesome-tag" },
+      ].to_json
+
+      create_post(
+        user: admin,
+        category: Fabricate(:category),
+        topic: Fabricate(:topic, tags: [Fabricate(:tag, name: "awesome-tag")]),
+        title: "This is a short meeting",
+        raw: "[event start=\"2025-06-03 10:00\" end=\"2025-06-03 11:00\"]\n[/event]",
+      )
+    end
+
+    it "display the event with the correct color" do
+      visit("/upcoming-events/month/2025/6/16")
+
+      expect(get_rgb_color(find(".fc-daygrid-event-dot"), "borderColor")).to eq("rgb(231, 76, 60)")
+    end
+  end
+
+  context "with category color", time: Time.utc(2025, 6, 2, 19, 00) do
+    before do
+      SiteSetting.map_events_to_color = [
+        { type: "category", color: "rgb(231, 76, 60)", slug: "awesome-category" },
+      ].to_json
+
+      create_post(
+        user: admin,
+        category: Fabricate(:category, slug: "awesome-category"),
+        title: "This is a short meeting",
+        raw: "[event start=\"2025-06-03 10:00\" end=\"2025-06-03 11:00\"]\n[/event]",
+      )
+    end
+
+    it "display the event with the correct color" do
+      visit("/upcoming-events/month/2025/6/16")
+
+      expect(get_rgb_color(find(".fc-daygrid-event-dot"), "borderColor")).to eq("rgb(231, 76, 60)")
+    end
+  end
 end

plugins/discourse-calendar/test/javascripts/acceptance/category-events-calendar-test.js

@@ -10,18 +10,6 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
     discourse_post_event_enabled: true,
     events_calendar_categories: "1",
     calendar_categories: "",
-    map_events_to_color: JSON.stringify([
-      {
-        type: "tag",
-        color: "rgb(231, 76, 60)",
-        slug: "awesome-tag",
-      },
-      {
-        type: "category",
-        color: "rgb(140,24,193)",
-        slug: "awesome-category",
-      },
-    ]),
   });
 
   needs.pretender((server, helper) => {
@@ -46,7 +34,6 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
               topic: {
                 id: 18449,
                 title: "This is an event",
-                tags: ["awesome-tag"],
               },
             },
             name: "Awesome Event",
@@ -70,7 +57,6 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
               topic: {
                 id: 18450,
                 title: "This is an event",
-                category_slug: "awesome-category",
               },
             },
             name: "Awesome Event 2",
@@ -93,7 +79,6 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
               topic: {
                 id: 18451,
                 title: "This is an event",
-                category_slug: "awesome-category",
               },
             },
             name: "Awesome Event 3<script>alert('my awesome event');</script>",
@@ -114,30 +99,6 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
       );
   });
 
-  test("events display the color configured in the map_events_to_color site setting", async function (assert) {
-    await visit("/c/bug/1");
-
-    assert
-      .dom(".fc-event")
-      .exists({ count: 4 }, "Events are displayed on the calendar");
-
-    assert
-      .dom(
-        ".fc-daygrid-event-harness a[href='/t/-/18449/1']  .fc-daygrid-event-dot"
-      )
-      .hasStyle({
-        "border-color": "rgb(231, 76, 60)",
-      });
-
-    assert
-      .dom(
-        ".fc-daygrid-event-harness a[href='/t/-/18450/1'] .fc-daygrid-event-dot"
-      )
-      .hasStyle({
-        "border-color": "rgb(140, 24, 193)",
-      });
-  });
-
   test("shows event calendar on category page", async function (assert) {
     await visit("/c/bug/1?foobar=true");