Pass the build arguments through to new_element_path.

Failing to do this leads to bad requests for nested element paths
so an api with self.site set to be

'foo.com/customers/:customer_id/items/:item_id'

will generate the url

/customers//items/new.json

when Item.build is called and the API returns an error code.

If we pass the attributes from build to new_element_path, this
behaviour is corrected such that build calls the url:

/customers/1/items/new.json

lib/active_resource/base.rb

@@ -766,7 +766,7 @@ def collection_path(prefix_options = {}, query_options = nil)
       # Returns the new resource instance.
       #
       def build(attributes = {})
-        attrs = self.format.decode(connection.get("#{new_element_path}", headers).body).merge(attributes)
+        attrs = self.format.decode(connection.get("#{new_element_path(attributes)}", headers).body)
         self.new(attrs)
       end
 

test/cases/base_test.rb

@@ -656,6 +656,20 @@ def test_build_with_custom_header
     Person.headers.delete('key')
   end
 
+  def test_build_without_attributes_for_prefix_call
+    ActiveResource::HttpMock.respond_to do |mock|
+      mock.get "/people/1/addresses/new.json", {}, StreetAddress.new.to_json
+    end
+    assert_raise(ActiveResource::InvalidRequestError) { StreetAddress.build }
+  end
+
+  def test_build_with_attributes_for_prefix_call
+    ActiveResource::HttpMock.respond_to do |mock|
+      mock.get "/people/1/addresses/new.json", {}, StreetAddress.new.to_json
+    end
+    assert_nothing_raised { StreetAddress.build(person_id: 1) }
+  end
+
   def test_save
     rick = Person.new
     assert rick.save