Use Rubocop and fix existing offences

Gemfile

@@ -18,5 +18,6 @@ group :development do
   gem 'minitest-around'
   gem 'pry'
   gem 'rack-test'
+  gem 'rubocop'
   gem 'shotgun'
 end

Gemfile.lock

@@ -16,7 +16,10 @@ GEM
       ast
       ruby-ll (~> 2.1)
     oj (2.15.1)
+    parser (2.3.1.4)
+      ast (~> 2.2)
     pg (0.18.4)
+    powerpack (0.1.1)
     pry (0.10.3)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
@@ -27,11 +30,19 @@ GEM
       rack
     rack-test (0.6.3)
       rack (>= 1.0)
+    rainbow (2.1.0)
     raindrops (0.16.0)
     rake (11.1.2)
+    rubocop (0.43.0)
+      parser (>= 2.3.1.1, < 3.0)
+      powerpack (~> 0.1)
+      rainbow (>= 1.99.1, < 3.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-ll (2.1.2)
       ansi
       ast
+    ruby-progressbar (1.8.1)
     sequel (4.35.0)
     sequel_pg (1.6.17)
       pg (>= 0.8.0)
@@ -44,6 +55,7 @@ GEM
       tilt (>= 1.3, < 3)
     slop (3.6.0)
     tilt (2.0.5)
+    unicode-display_width (1.1.1)
     unicorn (5.1.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
@@ -61,6 +73,7 @@ DEPENDENCIES
   rack-cors
   rack-test
   rake
+  rubocop
   sequel_pg
   shotgun
   sinatra
@@ -70,4 +83,4 @@ RUBY VERSION
    ruby 2.3.1p112
 
 BUNDLED WITH
-   1.12.3
+   1.13.6

Rakefile

@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 Dir.glob('lib/tasks/*.rake').each { |r| import r }
-task default: %w(db:migrate rates:load test)
+task default: %w(db:migrate rates:load test rubocop)

config.ru

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require './config/environment'
 require 'api'
 

config/unicorn.rb

@@ -1,7 +1,9 @@
 # frozen_string_literal: true
 
+worker_process_count = (ENV['WORKER_PROCESSES'] || 4).to_i
+
 preload_app true
-worker_processes((ENV['WORKER_PROCESSES'] || 4).to_i)
+worker_processes worker_process_count
 timeout 10
 
 before_fork do |_, _|

deploy/before_restart

@@ -1,4 +1,6 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
+
 oldrev, newrev = ARGV
 
 def run(cmd)
@@ -10,7 +12,7 @@ run 'whenever --update-crontab'
 
 tasks = []
 num_migrations = `git diff #{oldrev} #{newrev} --diff-filter=A --name-only -z db/migrate`.split("\0").size
-tasks << 'db:migrate' if num_migrations > 0
+tasks << 'db:migrate' if num_migrations.positive?
 tasks << 'rates:load'
 
 run "foreman run bundle exec rake #{tasks.join(' ')}"

lib/currency.rb

@@ -11,8 +11,7 @@ class Currency < Sequel::Model
     end
 
     def current_date
-      currency = recent.first
-      currency.date if currency
+      recent.first&.date
     end
 
     def current_date_before(value)

lib/quote.rb

@@ -27,7 +27,7 @@ class Quote
   private
 
   def base=(base)
-    @base = base ? base.upcase : DEFAULT_BASE
+    @base = base&.upcase || DEFAULT_BASE
   end
 
   def date=(date)
@@ -35,12 +35,9 @@ class Quote
     raise Invalid, 'Date too old' unless current_date
     @date = current_date
   rescue Sequel::DatabaseError => ex
-    if ex.wrapped_exception.is_a?(PG::DataException)
-      raise Invalid, 'Invalid date'
-    else
+    raise Invalid, 'Invalid date' if ex.wrapped_exception.is_a?(PG::DataException)
     raise
   end
-  end
 
   def find_rates
     quoted_against_default_base? ? find_default_rates : find_rebased_rates

lib/tasks/rubocop.rake

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new

spec/converter_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative 'helper'
 require 'converter'
 
@@ -29,7 +31,7 @@ describe Converter do
     end
 
     it 'should raise with invalid currency' do
-      quote.stub :rates, Hash.new do
+      quote.stub :rates, {} do
         -> { converter.convert(quote) }.must_raise Quote::Invalid, 'Invalid to'
       end
     end

spec/edge_cases_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative 'helper'
 require 'rack/test'
 require 'api'