Use Synvert to automatically use FactoryBot short syntax

It’s a long time since FactoryBot or FactoryGirl introduced short syntax, but it is still a good example to show how to use Synvert to refactor code.

The original syntax of FactoryBot is:

FactoryBot.create(:user)
FactoryBot.build(:user)
FactoryBot.build_stubbed(:user)

The short syntax is:

create(:user)
build(:user)
build_stubbed(:user)

First, I open the Synvert application, select language as ruby, set input as FactoryBot.create(:user) and output as create(:user), then click “Generate Snippet” button, it will generate the snippet as follows:

Synvert::Rewriter.new 'group', 'name' do
  within_files '**/*.rb' do
    find_node '.send[receiver=FactoryBot][message=create][arguments.size=1][arguments.0=:user]' do
      delete :receiver, :dot
    end
  end
end

It finds send node with receiver FactoryBot, message create and only one argument user, then it deletes the receiver and dot. But actually we don’t care about the argument, there are 2 ways,

1. we can simply remove the argument statement,

2. or we can add more input / output, add FactoryBot.create(:admin, is_admin: true) as input and create(:admin, is_admin: true) as output, then generate the snippet again.

Now the snippet is as follows:

Synvert::Rewriter.new 'group', 'name' do
  within_files '**/*.rb' do
    find_node '.send[receiver=FactoryBot][message=create]' do
      delete :receiver, :dot
    end
  end
end

It finds the FactoryBot.create code without caring about the argument, now we can search the code in the project.

Cool, it finds all FactoryBot.create and tries to delete the FactoryBot., now we can make the changes by clicking the “replace” icon.

It works for FactoryBot.create now, what about FactoryBot.build, FactoryBot.build_stubbed and other FactoryBot methods? We can use in operator to match multiple methods, let’s change the snippet as follows:

Synvert::Rewriter.new 'group', 'name' do
  within_files '**/*.rb' do
    find_node '.send[receiver=FactoryBot][message in (create build build_stubbed attributes_for create_list build_list)]' do
      delete :receiver, :dot
    end
  end
end

Let’s we search again.

Now it works for all FactoryBot methods, and we can replace them all.

The official snippet is here, it also inserts include FactoryBot::Syntax::Methods statement.