Merge pull request #379 from rails/schneems/error-when-asset-not-found

Explicit API to error when an asset is not found

lib/sprockets/base.rb

@@ -93,6 +93,18 @@ def [](*args)
       find_asset(*args)
     end
 
+    # Find asset by logical path or expanded path.
+    #
+    # If the asset is not found an error will be raised.
+    def find_asset!(*args)
+      asset = find_asset(*args)
+      if asset
+        return asset
+      else
+        raise_on_unknown_asset(*args)
+      end
+    end
+
     # Pretty inspect
     def inspect
       "#<#{self.class}:0x#{object_id.to_s(16)} " +
@@ -107,5 +119,13 @@ def compress_from_root(uri)
     def expand_from_root(uri)
       URITar.new(uri, self).expand
     end
+
+    private
+      def raise_on_unknown_asset(*args)
+        asset_name = args.shift
+        msg = String.new("Could not load asset #{ asset_name.inspect }")
+        msg << "with options #{ args.inspect }" unless args.empty?
+        raise Sprockets::NotFound, msg
+      end
   end
 end

lib/sprockets/environment.rb

@@ -31,6 +31,10 @@ def find_asset(*args)
       cached.find_asset(*args)
     end
 
+    def find_asset!(*args)
+      cached.find_asset!(*args)
+    end
+
     def find_all_linked_assets(*args, &block)
       cached.find_all_linked_assets(*args, &block)
     end

test/test_environment.rb

@@ -47,6 +47,18 @@ def self.test(name, &block)
     assert_equal "hello: world\n", context.call("JST['hello']", name: "world")
   end
 
+  test "find_asset! does not raise an exception when asset is found" do
+    @env.find_asset!("hello.js") # assert no raise
+  end
+
+  test "find_asset! raises an error when asset is not found" do
+    does_not_exist_file_name = "doesnotexist.blerg"
+    error = assert_raises(Sprockets::NotFound) do
+      @env.find_asset!(does_not_exist_file_name)
+    end
+    assert_match %r{#{does_not_exist_file_name}}, error.message
+  end
+
   test "asset_data_uri helper" do
     assert asset = @env["with_data_uri.css"]
     assert_equal "body {\n  background-image: url(data:image/gif;base64,R0lGODlhAQABAIAAAP%2F%2F%2FwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw%3D%3D) no-repeat;\n}\n", asset.to_s