refactor: address review comments for join view

test/membership/join_request_test.exs

@@ -38,6 +38,21 @@ defmodule Mv.Membership.JoinRequestTest do
     end
 
     test "persists first_name, last_name and form_data when provided" do
+      # Allowlist must include custom fields so FilterFormDataByAllowlist persists them
+      {:ok, settings} = Membership.get_settings()
+
+      Mv.Membership.update_settings(settings, %{
+        join_form_enabled: true,
+        join_form_field_ids: ["email", "first_name", "last_name", "city", "notes"],
+        join_form_field_required: %{
+          "email" => true,
+          "first_name" => false,
+          "last_name" => false,
+          "city" => false,
+          "notes" => false
+        }
+      })
+
       attrs =
         @valid_submit_attrs
         |> Map.put(:confirmation_token, "token-#{System.unique_integer([:positive])}")
@@ -128,8 +143,8 @@ defmodule Mv.Membership.JoinRequestTest do
 
       Mv.Membership.update_settings(settings, %{
         join_form_enabled: true,
-        join_form_field_ids: ["email", "first_name"],
-        join_form_field_required: %{"email" => true, "first_name" => false}
+        join_form_field_ids: ["email", "first_name", "city"],
+        join_form_field_required: %{"email" => true, "first_name" => false, "city" => false}
       })
 
       attrs = %{