add more specs

lib/params/base_validator.rb

@@ -65,11 +65,11 @@ module Params
       raise_error(message || "#{key} must follow the #{regexp.source} format")
     end
 
-    def unique(params, key, message: nil)
+    def unique_value(params, key, message: nil)
       return unless params.is_a?(Array)
       return if params.none?
       return if params.all? { |p| p[key].blank? }
-      return if params.pluck(key).uniq.size == params.pluck(key).size
+      return if params.pluck(key).compact_blank.uniq.size == params.pluck(key).compact_blank.size
 
       raise_error(message || "#{key} must be unique")
     end

lib/params/submission_create_validator.rb

@@ -60,7 +60,7 @@ module Params
       if params[:submitters].present?
         in_path(params, :submitters) do |submitters_params|
           type(submitters_params, 0, Hash)
-          unique(submitters_params, :role)
+          unique_value(submitters_params, :role)
         end
       end