map.rb in importmap-rails-0.7.0

- old
+ new

@@ -1,6 +1,7 @@
 require "pathname"
+require "active_support/evented_file_update_checker"
 
 class Importmap::Map
   attr_reader :packages, :directories
 
   def initialize
@@ -48,13 +49,27 @@
   # ensure that a html cache is invalidated when the import map is changed.
   #
   # Example:
   #
   #   class ApplicationController < ActionController::Base
-  #     etag { Rails.application.config.importmap.digest(resolver: helpers) if request.format&.html? }
+  #     etag { Rails.application.importmap.digest(resolver: helpers) if request.format&.html? }
   #   end
   def digest(resolver:)
     Digest::SHA1.hexdigest(to_json(resolver: resolver).to_s)
+  end
+
+  # Returns an instance ActiveSupport::EventedFileUpdateChecker configured to clear the cache of the map
+  # when the directories passed on initialization via `watches:` have changes. This is used in development
+  # and test to ensure the map caches are reset when javascript files are changed.
+  def cache_sweeper(watches: nil)
+    if watches
+      @cache_sweeper =
+        ActiveSupport::EventedFileUpdateChecker.new([], Array(watches).collect { |dir| [ dir, "js"] }.to_h) do
+          clear_cache
+        end
+    else
+      @cache_sweeper  
+    end
   end
 
   private
     MappedDir  = Struct.new(:dir, :path, :under, :preload, keyword_init: true)
     MappedFile = Struct.new(:name, :path, :preload, keyword_init: true)