From 4795c175c83d588571aba53c63246c914ddce280 Mon Sep 17 00:00:00 2001
From: Theodor Tonum <theodor@tonum.no>
Date: Thu, 16 Sep 2021 21:38:49 +0200
Subject: [PATCH] Improve serving of prehashed assets

See https://github.com/rails/jsbundling-rails/pull/21
---
 CHANGELOG.md                                       |  1 +
 lib/sprockets/server.rb                            | 12 +++++++++++-
 ...hed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js |  1 +
 test/test_server.rb                                | 14 ++++++++++++--
 4 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/server/app/javascripts/prehashed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ec6ca810..72574d902 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ Get upgrade notes from Sprockets 3.x to 4.x at https://github.com/rails/sprocket
 
 ## Master
 
+- Allow assets already fingerprinted to be served through `Sprockets::Server`
 - Do not fingerprint files that already contain a valid digest in their name
 - Remove remaining support for Ruby < 2.4.[#672](https://github.com/rails/sprockets/pull/672)
 
diff --git a/lib/sprockets/server.rb b/lib/sprockets/server.rb
index 7ed0d416b..ce425a322 100644
--- a/lib/sprockets/server.rb
+++ b/lib/sprockets/server.rb
@@ -35,7 +35,8 @@ def call(env)
       msg = "Served asset #{env['PATH_INFO']} -"
 
       # Extract the path from everything after the leading slash
-      path = Rack::Utils.unescape(env['PATH_INFO'].to_s.sub(/^\//, ''))
+      full_path = Rack::Utils.unescape(env['PATH_INFO'].to_s.sub(/^\//, ''))
+      path = full_path
 
       unless path.valid_encoding?
         return bad_request_response(env)
@@ -64,6 +65,15 @@ def call(env)
       # Look up the asset.
       asset = find_asset(path)
 
+      # Fallback to looking up the asset with the full path.
+      # This will make assets that are hashed with webpack or
+      # other js bundlers work consistently between production
+      # and development pipelines.
+      if asset.nil? && (asset = find_asset(full_path))
+        if_match = asset.etag if fingerprint
+        fingerprint = asset.etag
+      end
+
       if asset.nil?
         status = :not_found
       elsif fingerprint && asset.etag != fingerprint
diff --git a/test/fixtures/server/app/javascripts/prehashed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js b/test/fixtures/server/app/javascripts/prehashed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js
new file mode 100644
index 000000000..b336b22ec
--- /dev/null
+++ b/test/fixtures/server/app/javascripts/prehashed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js
@@ -0,0 +1 @@
+console.log("I was already hashed!");
\ No newline at end of file
diff --git a/test/test_server.rb b/test/test_server.rb
index b65ad809d..40b63c3c9 100644
--- a/test/test_server.rb
+++ b/test/test_server.rb
@@ -129,6 +129,16 @@ def app
     assert_equal 304, last_response.status
   end
 
+  test "200 response for prehashed asset with etag digest by sprockets" do
+    get "/assets/prehashed-988881adc9fc3655077dc2d4d757d480b5ea0e11.js"
+    assert_equal 200, last_response.status
+
+    etag = last_response.headers['ETag']
+    digest = etag[/"(.+)"/, 1]
+
+    assert_equal 'edabfd0f1ac5fcdae82cc7d92d1c52abb671797a3948fa9040aec1db8e61c327', digest
+  end
+
   test "ok response with fingerprint and if-nonematch etags don't match" do
     get "/assets/application.js"
     assert_equal 200, last_response.status
@@ -298,7 +308,7 @@ def app
 
     sandbox filename do
       get "/assets/tree.js"
-      assert_equal "var foo;\n\n(function() {\n  application.boot();\n})();\nvar bar;\nvar japanese = \"日本語\";\n", last_response.body
+      assert_equal %[var foo;\n\n(function() {\n  application.boot();\n})();\nvar bar;\nconsole.log("I was already hashed!");\nvar japanese = \"日本語\";\n], last_response.body
 
       File.open(filename, "w") do |f|
         f.write "var baz;\n"
@@ -309,7 +319,7 @@ def app
       File.utime(mtime, mtime, path)
 
       get "/assets/tree.js"
-      assert_equal "var foo;\n\n(function() {\n  application.boot();\n})();\nvar bar;\nvar baz;\nvar japanese = \"日本語\";\n", last_response.body
+      assert_equal %[var foo;\n\n(function() {\n  application.boot();\n})();\nvar bar;\nvar baz;\nconsole.log("I was already hashed!");\nvar japanese = \"日本語\";\n], last_response.body
     end
   end