Make environment version affect asset digest

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Get upgrade notes from Sprockets 3.x to 4.x at https://github.com/rails/sprockets/blob/master/UPGRADING.md
 
+## Next Release
+
+- Changing the version now busts the digest of all assets [#404]
+
 ## 4.0.0.beta3
 
 - Source Map fixes [#255] [#367]

lib/sprockets/loader.rb

@@ -163,7 +163,7 @@ def load_from_unloaded(unloaded)
           source = result.delete(:data)
           metadata = result
           metadata[:charset] = source.encoding.name.downcase unless metadata.key?(:charset)
-          metadata[:digest]  = digest(source)
+          metadata[:digest]  = digest(self.version + source)
           metadata[:length]  = source.bytesize
         else
           dependencies << build_file_digest_uri(unloaded.filename)

test/test_environment.rb

@@ -671,10 +671,10 @@ def setup
     assert_equal 2, asset.metadata[:selector_count]
   end
 
-  test "changing version doesn't affect the assets digest" do
+  test "changing version changes the digest of the asset" do
     old_asset_digest = @env["gallery.js"].hexdigest
     @env.version = 'v2'
-    assert old_asset_digest == @env["gallery.js"].hexdigest
+    assert old_asset_digest != @env["gallery.js"].hexdigest
   end
 
   test "bundled asset is stale if its mtime is updated or deleted" do