[#1794] Fixed search query splitting regex to deal with Unicode. Adjusted a test.

lib/pleroma/web/mastodon_api/controllers/search_controller.ex

@@ -124,7 +124,7 @@ defp resource_search(:v1, "hashtags", query, _options) do
   defp prepare_tags(query, add_joined_tag \\ true) do
     tags =
       query
-      |> String.split(~r/[^#\w]+/, trim: true)
+      |> String.split(~r/[^#\w]+/u, trim: true)
       |> Enum.uniq_by(&String.downcase/1)
 
     explicit_tags = Enum.filter(tags, fn tag -> String.starts_with?(tag, "#") end)

test/web/mastodon_api/controllers/search_controller_test.exs

@@ -71,6 +71,10 @@ test "search", %{conn: conn} do
         get(conn, "/api/v2/search?q=天子")
         |> json_response_and_validate_schema(200)
 
+      assert results["hashtags"] == [
+               %{"name" => "天子", "url" => "#{Web.base_url()}/tag/天子"}
+             ]
+
       [status] = results["statuses"]
       assert status["id"] == to_string(activity.id)
     end