Synvert

Improve and refactor ruby code easier

http://xinminlabs.github.io/synvert-rubyconf-tw-2014

Richard Huang

Xinmin Labs

About Me

Founder at Xinmin Labs
Full Stacked Developer
Open Source Enthusiast

@flyerhzm

What's synvert

synvert = syntax + convert

Why synvert

Ruby world involves fast

FactoryGirl prefers short syntax

post = FactoryGirl.create(:post)

post = create(:post)

RSpec will deprecate should syntax in favor of expect

1.should == 1

expect(1).to eq 1

Rails 4 has deprecated dynamic finders

user = User.find_last_by_email_and_active('flyerhzm@xinminlabs.com', true)

user = User.where(email: 'flyerhzm@xinminlabs.com', active: true).last

Changes happen frequently in ruby community

We have to

Convert syntax for project 1

......

Convert syntax for project N

Other teams also have to

Convert syntax for their projects

DRY

Some tools can analyze and find out old deprecated code

rails_best_practices

But you still have to change code manually

Synvert can do more

As automaic as possible

How synvert works

Synvert + Snippets

Background

AST

Parser

Ruby code

post = FactoryGirl.create(:post)

AST

(lvasgn :post
  (send
    (const nil :FactoryGirl) :create
    (sym :post)))

Synvert can find specified files
Synvert can convert ruby source code to ast nodes
Synvert can find out specified ast nodes
Synvert can check if specified ast node exist or not
Synvert can add / replace / remove specifed code

Snippets tell synvert what to do

Snippet

Synvert::Rewriter.new 'synvert_name' do        # Rewriter
  if_gem 'gem_name', {gte: '1.0.0'}            # GemSpec

  within_files '**/*.rb' do                    # Instance
    within_node rules_to_find_node do          # Scope
      unless_exist_node rules_to_check_node do # Condition
        insert "what code to insert"           # Action
      end
    end
  end
end

DSL: http://xinminlabs.github.io/synvert/dsl/

Rules: http://xinminlabs.github.io/synvert/rules/

Example

use FactoryGirl short syntax

Adds

include FactoryGirl::Syntax::Methods

class Test::Unit::TestCase

in file

test/test_helper.rb

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  within_file 'test/test_helper.rb' do
    with_node type: 'class', name: 'Test::Unit::TestCase' do
      insert 'include FactoryGirl::Syntax::Methods'
    end
  end
end

From factory_girl 2.0.0, so let's check the gem version.

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  # check if factory_girl gem greater than or equal to 2.0.0 in Gemfile.lock
  if_gem 'factory_girl', {gte: '2.0.0'}

  within_file 'test/test_helper.rb' do
    with_node type: 'class', name: 'Test::Unit::TestCase' do
      insert 'include FactoryGirl::Syntax::Methods'
    end
  end
end

It works, but it inserts code every time even when

include FactoryGirl::Syntax::Methods

already exist in the class,
so let's check if code doesn't exist, then insert.

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  within_file 'test/test_helper.rb' do
    with_node type: 'class', name: 'Test::Unit::TestCase' do
      # unless include FactoryGirl::Syntax::Methods exists
      unless_exist_node type: 'send', message: 'include',
                        arguments: ['FactoryGirl::Syntax::Methods'] do
        insert 'include FactoryGirl::Syntax::Methods'
      end
    end
  end
end

It should also work in minitest and activesupport testcase

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  within_file 'test/test_helper.rb' do
    %w(Test::Unit::TestCase ActiveSupport::TestCase
        MiniTest::Unit::TestCase MiniTest::Spec
        MiniTest::Rails::ActiveSupport::TestCase).each do |class_name|
      with_node type: 'class', name: class_name do
        unless_exist_node type: 'send', message: 'include',
                          arguments: ['FactoryGirl::Syntax::Methods'] do
          insert 'include FactoryGirl::Syntax::Methods'
        end
      end
    end
  end
end

For RSpec, it does a bit different

RSpec.configure do |config|
  config.incldue FactoryGirl::Syntax::Methods
end

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  within_file 'spec/spec_helper.rb' do
    # match code RSpec.configure do |config|; ... end
    within_node type: 'block', caller: {receiver: 'RSpec',
                                        message: 'configure'} do
      unless_exist_node type: 'send', message: 'include',
                        arguments: ['FactoryGirl::Syntax::Methods'] do
        # {{ }} is executed on current node, so we can add or
        # replace with some old code,
        # arguments are [config], arguments.first is config,
        insert "{{arguments.first}}.include FactoryGirl::Syntax::Methods"
      end
    end
  end
end

Finally, apply it for cucumber as well.

World(FactoryGirl::Syntax::Methods)

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  within_file 'features/support/env.rb' do
    # current node is the root node of env.rb file
    # we don't need with_node / within_node here
    unless_exist_node type: 'send', message: 'World',
                      arguments: ['FactoryGirl::Syntax::Methods'] do
      insert "World(FactoryGirl::Syntax::Methods)"
    end
  end
end

Now we can replace

FactoryGirl.create(:post)

with

create(:post)

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  %w(test/**/*.rb spec/**/*.rb features/**/*.rb).each do |file_pattern|
    # find all files in test/, spec/ and features/
    within_files file_pattern do
      with_node type: 'send', receiver: 'FactoryGirl', message: 'create' do
        # for FactoryGirl.create(:post, title: 'post'),
        # arguments are :post, title: 'post'
        replace_with "create({{arguments}})"
      end
    end
  end
end

There are other short syntaxes,
e.g. build, create_list, build_list, etc.

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  if_gem 'factory_girl', {gte: '2.0.0'}

  %w(test/**/*.rb spec/**/*.rb features/**/*.rb).each do |file_pattern|
    within_files file_pattern do
      %w(create build attributes_for build_stubbed create_list build_list
          create_pair build_pair).each do |message|
        with_node type: 'send', receiver: 'FactoryGirl', message: message do
          replace_with "#{message}({{arguments}})"
        end
      end
    end
  end
end

Finally write description for the rewriter

Synvert::Rewriter.new 'factory_girl_short_syntax' do
  description <<-EOF
1. it adds FactoryGirl::Syntax::methods module to RSpec, Test::Unit,
   Cucumber, Spainach, MiniTest, MiniTest::Spec, minitest-rails.

2. it converts to short syntax.

    FactoryGirl.create(...) => create(...)
    FactoryGirl.build(...) => build(...)
    ......
  EOF

  if_gem 'factory_girl', {gte: '2.0.0'}

  ......
end

Complex Example

Convert rails dynamic finders

From rails 4, dynamic finders are deprecated

User.find_last_by_email_and_active('flyerhzm@xinminlabs.com', true)

User.where(email: 'flyerhzm@xinminlabs.com', active: true).last

Synvert::Rewriter.new "convert_dynamic_finders" do
  within_files '**/*.rb' do
    with_node type: 'send', message: /^find_last_by_(.*)/ do
      # node is current matching ast node
      # you can add any ruby code in the block
      # here we convert dynamic finder message to hash params, e.g.
      # email_and_active('email', active) to email: 'email', active: active
      #
      # node.source(self) is used to get original ruby source code
      # {{receiver}} gets the receiver of current ast node
      fields = node.message.to_s["find_last_by_".length..-1].split("_and_")
      hash_params = fields.length.times.map { |i|
        fields[i] + ": " + node.arguments[i].source(self)
      }.join(", ")
      replace_with "{{receiver}}.where(#{hash_params}).last"
    end
  end
end

Let's use helper_method for other dynamic finders.

Synvert::Rewriter.new "convert_dynamic_finders" do
  helper_method 'dynamic_finder_to_hash' do |prefix|
    fields = node.message.to_s[prefix.length..-1].split("_and_")
    fields.length.times.map { |i|
      fields[i] + ": " + node.arguments[i].source(self)
    }.join(", ")
  end
  within_files '**/*.rb' do
    with_node type: 'send', message: /^find_all_by_(.*)/ do
      hash_params = dynamic_finder_to_hash("find_all_by_")
      replace_with "{{receiver}}.where(#{hash_params})"
    end
    with_node type: 'send', message: /^find_last_by_(.*)/ do
      hash_params = dynamic_finder_to_hash("find_last_by_")
      replace_with "{{receiver}}.where(#{hash_params}).last"
    end
    ......
  end
end

Available Snippets

factory_girl_short_syntax
upgrade_rails_3_0_to_3_1
upgrade_rails_3_1_to_3_2
upgrade_rails_3_2_to_4_0
rspec_new_syntax
ruby_new_hash_syntax
ruby_new_lambda_syntax
......