MastoAPI: Add categories to custom emojis

Note: This isn’t in a release yet, can be seen in mastofe on the
rebase/glitch-soc branch.

CHANGELOG.md

@@ -27,6 +27,7 @@ Configuration: `federation_incoming_replies_max_depth` option
 - Admin API: Allow querying user by ID
 - Added synchronization of following/followers counters for external users
 - Configuration: `enabled` option for `Pleroma.Emails.Mailer`, defaulting to `false`.
+- Mastodon API: Add support for categories for custom emojis by reusing the group feature. <https://github.com/tootsuite/mastodon/pull/11196>
 
 ## [1.0.0] - 2019-06-29
 ### Security

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

@@ -299,7 +299,9 @@ defp mastodonized_emoji do
         "static_url" => url,
         "visible_in_picker" => true,
         "url" => url,
-        "tags" => tags
+        "tags" => tags,
+        # Assuming that a comma is authorized in the category name
+        "category" => (tags -- ["Custom"]) |> Enum.join(",")
       }
     end)
   end

test/web/mastodon_api/mastodon_api_controller_test.exs

@@ -2958,6 +2958,7 @@ test "with tags", %{conn: conn} do
       assert Map.has_key?(emoji, "static_url")
       assert Map.has_key?(emoji, "tags")
       assert is_list(emoji["tags"])
+      assert Map.has_key?(emoji, "category")
       assert Map.has_key?(emoji, "url")
       assert Map.has_key?(emoji, "visible_in_picker")
     end