Improve detection of files already digested

lib/sprockets/digest_utils.rb

@@ -183,13 +183,9 @@ def hexdigest_integrity_uri(hexdigest)
     #
     # name - The name of the asset
     #
-    # Returns true if the name contains a digest recognized by one of the valid digest classes
+    # Returns true if the name contains a digest like string and .digested before the extension
     def already_digested?(name)
-      return if name.nil?
-
-      if hexdigest = name.scan(/[a-fA-F0-9]+\z/).last
-        detect_digest_class(unpack_hexdigest(hexdigest))
-      end
+      return name =~ /-([0-9a-f]{7,128})\.digested/
     end
 
     private

test/test_asset.rb

@@ -1136,13 +1136,13 @@ def setup
   test "digest path" do
     path     = File.expand_path("test/fixtures/asset/application")
     original = "#{path}.js"
-    digested = "#{path}-d41d8cd98f00b204e9800998ecf8427e.js"
+    digested = "#{path}-d41d8cd98f00b204e9800998ecf8427e.digested.js"
     FileUtils.cp(original, digested)
 
-    assert_equal "application-d41d8cd98f00b204e9800998ecf8427e.js",
-      asset("application-d41d8cd98f00b204e9800998ecf8427e.js").digest_path
+    assert_equal "application-d41d8cd98f00b204e9800998ecf8427e.digested.js",
+      asset("application-d41d8cd98f00b204e9800998ecf8427e.digested.js").digest_path
   ensure
-    FileUtils.rm(digested) if File.exists?(digested)
+    FileUtils.rm(digested) if File.exist?(digested)
   end
 
   def asset(logical_path, options = {})

test/test_digest_utils.rb

@@ -97,14 +97,10 @@ def test_hexdigest_integrity_uri
 
   def test_already_digested
     refute already_digested?(nil)
-    refute already_digested?("application-d41d8cd98f00b204e9800998ecf8427z")
-    refute already_digested?("application-d41d8cd98f00b204e9800998ecf8427ef")
-    refute already_digested?("application-d41d8cd98f00b204e9800998ecf8427e-")
-
-    assert already_digested?("application-" + Digest::MD5.new.hexdigest)
-    assert already_digested?("application-" + Digest::SHA1.new.hexdigest)
-    assert already_digested?("application-" + Digest::SHA256.new.hexdigest)
-    assert already_digested?("application-" + Digest::SHA384.new.hexdigest)
-    assert already_digested?("application-" + Digest::SHA512.new.hexdigest)
+    refute already_digested?("application-abc123.digested")
+    refute already_digested?("application-abcd1234")
+
+    assert already_digested?("application-abcd1234.digested")
+    assert already_digested?("application-abcd1234.digested.map")
   end
 end