From af8073736b0b5ea5abcbcfa11ad885fc9b6128c0 Mon Sep 17 00:00:00 2001
From: Breno Gazzola <breno.gazzola@gmail.com>
Date: Fri, 18 Feb 2022 16:34:50 -0300
Subject: [PATCH] Deduplicate paths

---
 lib/propshaft/load_path.rb       | 14 +++++++++++---
 test/propshaft/load_path_test.rb | 15 +++++++++++++++
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/lib/propshaft/load_path.rb b/lib/propshaft/load_path.rb
index 944d8aa..cb67cd9 100644
--- a/lib/propshaft/load_path.rb
+++ b/lib/propshaft/load_path.rb
@@ -4,7 +4,7 @@ class Propshaft::LoadPath
   attr_reader :paths, :version
 
   def initialize(paths = [], version: nil)
-    @paths   = Array(paths).collect { |path| Pathname.new(path) }
+    @paths = dedup(paths)
     @version = version
   end
 
@@ -33,8 +33,8 @@ def manifest
   # and test to ensure the map caches are reset when javascript files are changed.
   def cache_sweeper
     @cache_sweeper ||= begin
-      exts_to_watch  = Mime::EXTENSION_LOOKUP.map(&:first)
-      files_to_watch = Array(paths).collect { |dir| [ dir.to_s, exts_to_watch ] }.to_h
+      exts_to_watch = Mime::EXTENSION_LOOKUP.map(&:first)
+      files_to_watch = Array(paths).collect { |dir| [dir.to_s, exts_to_watch] }.to_h
 
       Rails.application.config.file_watcher.new([], files_to_watch) do
         clear_cache
@@ -65,4 +65,12 @@ def without_dotfiles(files)
     def clear_cache
       @cached_assets_by_path = nil
     end
+
+    def dedup(paths)
+      [].tap do |deduped|
+        Array(paths).sort.each do |path|
+          deduped << Pathname.new(path) if deduped.blank? || !path.to_s.start_with?(deduped.last.to_s)
+        end
+      end
+    end
 end
diff --git a/test/propshaft/load_path_test.rb b/test/propshaft/load_path_test.rb
index 1985f07..1d4f06a 100644
--- a/test/propshaft/load_path_test.rb
+++ b/test/propshaft/load_path_test.rb
@@ -55,6 +55,21 @@ class Propshaft::LoadPathTest < ActiveSupport::TestCase
     assert_nil Propshaft::LoadPath.new(Pathname.new("#{__dir__}/../fixtures/assets/nowhere")).find("missing")
   end
 
+  test "deduplicate paths" do
+    load_path = Propshaft::LoadPath.new [
+      "app/assets/stylesheets",
+      "app/assets/images",
+      "app/assets",
+      "app/javascript",
+      "app/javascript/packs"
+    ]
+
+    paths = load_path.paths
+    assert_equal 2, paths.count
+    assert_equal Pathname.new("app/assets"), paths.first
+    assert_equal Pathname.new("app/javascript"), paths.last
+  end
+
   private
     def find_asset(logical_path)
       Propshaft::Asset.new(