Make Rubocop happy

Author: peterzhu2118

Rakefile

@@ -13,4 +13,4 @@ require "rubocop/rake_task"
 
 RuboCop::RakeTask.new
 
-task default: %i[test rubocop]
+task default: [:test, :rubocop]

shopify-ruby-definitions.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
   # Specify which files should be added to the gem when it is released.
   # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files = Dir.chdir(__dir__) do
-    `git ls-files -z`.split("\x0").reject do |f|
+    %x(git ls-files -z).split("\x0").reject do |f|
       (f == __FILE__) || f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|circleci)|appveyor)})
     end
   end

test/test_helper.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-$LOAD_PATH.unshift File.expand_path("../lib", __dir__)
+$LOAD_PATH.unshift(File.expand_path("../lib", __dir__))
 require "shopify_ruby_definitions"
 
 require "minitest/autorun"