From a075b0a1bdb9d5785e69521d229649da895810da Mon Sep 17 00:00:00 2001
From: Nicolas Rodriguez <nico@nicoladmin.fr>
Date: Mon, 23 Sep 2024 18:32:21 +0200
Subject: [PATCH] Update the code style across the project (#242)

Eventually, we'll move to standard, but this is a nice improvement which
makes working with Appraisal much more pleasant.

This commit does the following:

* use double quotes everywhere
* use the new Ruby 1.9 hash syntax
* use uppercase heredoc delimiters
* add parentheses to nested method call
* add missing frozen string literal comment
* %w-literals should be delimited by [ and ]
* space inside } is missing
* fix indentation
* avoid comma after the last parameter of a method call
* remove unnecessary disabling of Layout/LineLength
* remove unnecessary spacing
* use hash literal {} instead of Hash.new
* place the . on the next line, together with the method name
* use 2 spaces for indentation in a heredoc by using <<~ instead of <<-
* make sure that the block will be associated with the PARTS.map method call
* use class << self instead of def self. to define class methods
* add missing space
---
 Rakefile                                      | 14 ++--
 appraisal.gemspec                             | 22 ++---
 exe/appraisal                                 | 10 ++-
 lib/appraisal.rb                              |  6 +-
 lib/appraisal/appraisal.rb                    | 34 ++++----
 lib/appraisal/appraisal_file.rb               | 12 +--
 lib/appraisal/bundler_dsl.rb                  | 23 ++---
 lib/appraisal/cli.rb                          | 84 ++++++++++---------
 lib/appraisal/command.rb                      |  4 +-
 lib/appraisal/conditional.rb                  |  2 +
 lib/appraisal/customize.rb                    |  4 +-
 lib/appraisal/dependency.rb                   |  6 +-
 lib/appraisal/dependency_list.rb              |  6 +-
 lib/appraisal/errors.rb                       |  2 +
 lib/appraisal/gemfile.rb                      |  2 +
 lib/appraisal/gemspec.rb                      |  8 +-
 lib/appraisal/git.rb                          |  4 +-
 lib/appraisal/group.rb                        | 12 +--
 lib/appraisal/path.rb                         |  4 +-
 lib/appraisal/platform.rb                     | 12 +--
 lib/appraisal/source.rb                       | 12 +--
 lib/appraisal/task.rb                         | 14 ++--
 lib/appraisal/utils.rb                        | 13 ++-
 lib/appraisal/version.rb                      |  2 +
 ...als_file_bundler_dsl_compatibility_spec.rb | 46 +++++-----
 .../bundle_with_custom_path_spec.rb           | 35 ++++----
 spec/acceptance/bundle_without_spec.rb        | 12 +--
 spec/acceptance/cli/clean_spec.rb             | 24 +++---
 spec/acceptance/cli/generate_spec.rb          | 26 +++---
 spec/acceptance/cli/help_spec.rb              | 28 ++++---
 spec/acceptance/cli/install_spec.rb           | 78 +++++++----------
 spec/acceptance/cli/list_spec.rb              | 20 +++--
 spec/acceptance/cli/run_spec.rb               | 50 +++++------
 spec/acceptance/cli/update_spec.rb            | 38 +++++----
 spec/acceptance/cli/version_spec.rb           |  2 +
 spec/acceptance/cli/with_no_arguments_spec.rb | 18 ++--
 .../gemfile_dsl_compatibility_spec.rb         | 62 +++++++-------
 spec/acceptance/gemspec_spec.rb               | 50 +++++------
 spec/appraisal/appraisal_file_spec.rb         | 10 ++-
 spec/appraisal/appraisal_spec.rb              | 41 +++++----
 spec/appraisal/customize_spec.rb              | 33 ++++----
 spec/appraisal/dependency_list_spec.rb        |  2 +
 spec/appraisal/gemfile_spec.rb                | 75 +++++++++--------
 spec/appraisal/utils_spec.rb                  | 47 +++++------
 spec/spec_helper.rb                           | 12 +--
 spec/support/acceptance_test_helpers.rb       | 50 +++++------
 spec/support/dependency_helpers.rb            | 18 ++--
 spec/support/stream_helpers.rb                |  2 +
 48 files changed, 575 insertions(+), 516 deletions(-)

diff --git a/Rakefile b/Rakefile
index 3925e1e8..f8d79dbc 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,12 +1,14 @@
-require 'bundler/setup'
-require 'bundler/gem_tasks'
-require 'rspec/core/rake_task'
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "bundler/gem_tasks"
+require "rspec/core/rake_task"
 
 RSpec::Core::RakeTask.new do |t|
-  t.pattern = 'spec/**/*_spec.rb'
+  t.pattern = "spec/**/*_spec.rb"
   t.ruby_opts = %w[-w]
   t.verbose = false
 end
 
-desc 'Default: run the rspec examples'
-task :default => [:spec]
+desc "Default: run the rspec examples"
+task default: [:spec]
diff --git a/appraisal.gemspec b/appraisal.gemspec
index 9bce0d83..d136a37f 100644
--- a/appraisal.gemspec
+++ b/appraisal.gemspec
@@ -3,24 +3,24 @@
 require_relative "lib/appraisal/version"
 
 Gem::Specification.new do |s|
-  s.name        = 'appraisal'
+  s.name        = "appraisal"
   s.version     = Appraisal::VERSION.dup
   s.platform    = Gem::Platform::RUBY
-  s.authors     = ['Joe Ferris', 'Prem Sichanugrist']
-  s.email       = ['jferris@thoughtbot.com', 'prem@thoughtbot.com']
-  s.homepage    = 'http://github.com/thoughtbot/appraisal'
-  s.summary     = 'Find out what your Ruby gems are worth'
+  s.authors     = ["Joe Ferris", "Prem Sichanugrist"]
+  s.email       = ["jferris@thoughtbot.com", "prem@thoughtbot.com"]
+  s.homepage    = "http://github.com/thoughtbot/appraisal"
+  s.summary     = "Find out what your Ruby gems are worth"
   s.description = 'Appraisal integrates with bundler and rake to test your library against different versions of dependencies in repeatable scenarios called "appraisals."'
-  s.license     = 'MIT'
+  s.license     = "MIT"
 
   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
-  s.executables   = `git ls-files -- exe/*`.split("\n").map{ |f| File.basename(f) }
-  s.bindir        = 'exe'
+  s.executables   = `git ls-files -- exe/*`.split("\n").map { |f| File.basename(f) }
+  s.bindir        = "exe"
 
   s.required_ruby_version = ">= 2.3.0"
 
-  s.add_dependency('rake')
-  s.add_dependency('bundler')
-  s.add_dependency('thor', '>= 0.14.0')
+  s.add_dependency("rake")
+  s.add_dependency("bundler")
+  s.add_dependency("thor", ">= 0.14.0")
 end
diff --git a/exe/appraisal b/exe/appraisal
index 95f478a4..4e963840 100755
--- a/exe/appraisal
+++ b/exe/appraisal
@@ -1,8 +1,10 @@
 #!/usr/bin/env ruby
-require 'rubygems'
-require 'bundler/setup'
-require 'appraisal'
-require 'appraisal/cli'
+# frozen_string_literal: true
+
+require "rubygems"
+require "bundler/setup"
+require "appraisal"
+require "appraisal/cli"
 
 begin
   Appraisal::CLI.start
diff --git a/lib/appraisal.rb b/lib/appraisal.rb
index 9b7be847..3f5c8aa5 100644
--- a/lib/appraisal.rb
+++ b/lib/appraisal.rb
@@ -1,4 +1,6 @@
-require 'appraisal/version'
-require 'appraisal/task'
+# frozen_string_literal: true
+
+require "appraisal/version"
+require "appraisal/task"
 
 Appraisal::Task.new
diff --git a/lib/appraisal/appraisal.rb b/lib/appraisal/appraisal.rb
index 7d7634d0..86f2c3eb 100644
--- a/lib/appraisal/appraisal.rb
+++ b/lib/appraisal/appraisal.rb
@@ -1,9 +1,11 @@
-require 'appraisal/gemfile'
-require 'appraisal/command'
+# frozen_string_literal: true
+
+require "appraisal/gemfile"
+require "appraisal/command"
 require "appraisal/customize"
-require 'appraisal/utils'
-require 'fileutils'
-require 'pathname'
+require "appraisal/utils"
+require "fileutils"
+require "pathname"
 
 module Appraisal
   # Represents one appraisal and its dependencies
@@ -79,15 +81,15 @@ def install(options = {})
       command = commands.join(" || ")
 
       if Bundler.settings[:path]
-        env = { 'BUNDLE_DISABLE_SHARED_GEMS' => '1' }
-        Command.new(command, :env => env).run
+        env = { "BUNDLE_DISABLE_SHARED_GEMS" => "1" }
+        Command.new(command, env: env).run
       else
         Command.new(command).run
       end
     end
 
     def update(gems = [])
-      Command.new(update_command(gems), :gemfile => gemfile_path).run
+      Command.new(update_command(gems), gemfile: gemfile_path).run
     end
 
     def gemfile_path
@@ -107,10 +109,10 @@ def relativize
       relative_path = current_directory.relative_path_from(gemfile_root).cleanpath
       lockfile_content = File.read(lockfile_path)
 
-      File.open(lockfile_path, 'w') do |file|
+      File.open(lockfile_path, "w") do |file|
         file.write lockfile_content.gsub(
           / #{current_directory}/,
-          " #{relative_path}",
+          " #{relative_path}"
         )
       end
     end
@@ -119,16 +121,16 @@ def relativize
 
     def check_command
       gemfile_option = "--gemfile='#{gemfile_path}'"
-      ['bundle', 'check', gemfile_option]
+      ["bundle", "check", gemfile_option]
     end
 
     def install_command(options = {})
       gemfile_option = "--gemfile='#{gemfile_path}'"
-      ['bundle', 'install', gemfile_option, bundle_options(options)].compact
+      ["bundle", "install", gemfile_option, bundle_options(options)].compact
     end
 
     def update_command(gems)
-      ['bundle', 'update', *gems].compact
+      ["bundle", "update", *gems].compact
     end
 
     def gemfile_root
@@ -148,7 +150,7 @@ def lockfile_path
     end
 
     def clean_name
-      name.gsub(/[^\w\.]/, '_')
+      name.gsub(/[^\w\.]/, "_")
     end
 
     def bundle_options(options)
@@ -159,8 +161,8 @@ def bundle_options(options)
         if Utils.support_parallel_installation?
           options_strings << "--jobs=#{jobs}"
         else
-          warn 'Your current version of Bundler does not support parallel installation. Please ' +
-            'upgrade Bundler to version >= 1.4.0, or invoke `appraisal` without `--jobs` option.'
+          warn "Your current version of Bundler does not support parallel installation. Please " +
+            "upgrade Bundler to version >= 1.4.0, or invoke `appraisal` without `--jobs` option."
         end
       end
 
diff --git a/lib/appraisal/appraisal_file.rb b/lib/appraisal/appraisal_file.rb
index f5ade60d..2d182038 100644
--- a/lib/appraisal/appraisal_file.rb
+++ b/lib/appraisal/appraisal_file.rb
@@ -1,7 +1,9 @@
-require 'appraisal/appraisal'
+# frozen_string_literal: true
+
+require "appraisal/appraisal"
 require "appraisal/customize"
-require 'appraisal/errors'
-require 'appraisal/gemfile'
+require "appraisal/errors"
+require "appraisal/gemfile"
 
 module Appraisal
   # Loads and parses Appraisals file
@@ -15,7 +17,7 @@ def self.each(&block)
     def initialize
       @appraisals = []
       @gemfile = Gemfile.new
-      @gemfile.load(ENV['BUNDLE_GEMFILE'] || 'Gemfile')
+      @gemfile.load(ENV["BUNDLE_GEMFILE"] || "Gemfile")
 
       if File.exist? path
         run IO.read(path)
@@ -45,7 +47,7 @@ def run(definitions)
     end
 
     def path
-      'Appraisals'
+      "Appraisals"
     end
   end
 end
diff --git a/lib/appraisal/bundler_dsl.rb b/lib/appraisal/bundler_dsl.rb
index ebe039f8..e102f4cd 100644
--- a/lib/appraisal/bundler_dsl.rb
+++ b/lib/appraisal/bundler_dsl.rb
@@ -1,22 +1,24 @@
+# frozen_string_literal: true
+
 require "appraisal/dependency_list"
 
 module Appraisal
   class BundlerDSL
     attr_reader :dependencies
 
-    PARTS = %w(source ruby_version gits paths dependencies groups
-               platforms source_blocks install_if gemspec)
+    PARTS = %w[source ruby_version gits paths dependencies groups
+               platforms source_blocks install_if gemspec]
 
     def initialize
       @sources = []
       @ruby_version = nil
       @dependencies = DependencyList.new
       @gemspecs = []
-      @groups = Hash.new
-      @platforms = Hash.new
-      @gits = Hash.new
-      @paths = Hash.new
-      @source_blocks = Hash.new
+      @groups = {}
+      @platforms = {}
+      @gits = {}
+      @paths = {}
+      @source_blocks = {}
       @git_sources = {}
       @install_if = {}
     end
@@ -80,11 +82,11 @@ def path(source, options = {}, &block)
     end
 
     def to_s
-      Utils.join_parts PARTS.map { |part| send("#{part}_entry") }
+      Utils.join_parts(PARTS.map { |part| send("#{part}_entry") })
     end
 
     def for_dup
-      Utils.join_parts PARTS.map { |part| send("#{part}_entry_for_dup") }
+      Utils.join_parts(PARTS.map { |part| send("#{part}_entry_for_dup") })
     end
 
     def gemspec(options = {})
@@ -134,8 +136,7 @@ def dependencies_entry_for_dup
       @dependencies.for_dup
     end
 
-    %i[gits paths platforms groups source_blocks install_if].
-      each do |method_name|
+    %i[gits paths platforms groups source_blocks install_if].each do |method_name|
       class_eval <<-METHODS, __FILE__, __LINE__
         private
 
diff --git a/lib/appraisal/cli.rb b/lib/appraisal/cli.rb
index c6970a35..d92577ba 100644
--- a/lib/appraisal/cli.rb
+++ b/lib/appraisal/cli.rb
@@ -1,52 +1,56 @@
-require 'thor'
-require 'fileutils'
+# frozen_string_literal: true
+
+require "thor"
+require "fileutils"
 
 module Appraisal
   class CLI < Thor
     default_task :install
     map ["-v", "--version"] => "version"
 
-    # Override help command to print out usage
-    def self.help(shell, subcommand = false)
-      shell.say strip_heredoc(<<-help)
-        Appraisal: Find out what your Ruby gems are worth.
+    class << self
+      # Override help command to print out usage
+      def help(shell, subcommand = false)
+        shell.say strip_heredoc(<<-HELP)
+          Appraisal: Find out what your Ruby gems are worth.
 
-        Usage:
-          appraisal [APPRAISAL_NAME] EXTERNAL_COMMAND
+          Usage:
+            appraisal [APPRAISAL_NAME] EXTERNAL_COMMAND
 
-          If APPRAISAL_NAME is given, only run that EXTERNAL_COMMAND against the given
-          appraisal, otherwise it runs the EXTERNAL_COMMAND against all appraisals.
-      help
+            If APPRAISAL_NAME is given, only run that EXTERNAL_COMMAND against the given
+            appraisal, otherwise it runs the EXTERNAL_COMMAND against all appraisals.
+        HELP
 
-      if File.exist?('Appraisals')
-        shell.say
-        shell.say 'Available Appraisal(s):'
+        if File.exist?("Appraisals")
+          shell.say
+          shell.say "Available Appraisal(s):"
 
-        AppraisalFile.each do |appraisal|
-          shell.say "  - #{appraisal.name}"
+          AppraisalFile.each do |appraisal|
+            shell.say "  - #{appraisal.name}"
+          end
         end
-      end
 
-      shell.say
+        shell.say
 
-      super
-    end
+        super
+      end
 
-    def self.exit_on_failure?
-      true
+      def exit_on_failure?
+        true
+      end
     end
 
-    desc 'install', 'Resolve and install dependencies for each appraisal'
-    method_option 'jobs', :aliases => 'j', :type => :numeric, :default => 1,
-      :banner => 'SIZE',
-      :desc => 'Install gems in parallel using the given number of workers.'
-    method_option 'retry', :type => :numeric, :default => 1,
-      :desc => 'Retry network and git requests that have failed'
-    method_option "without", :banner => "GROUP_NAMES",
-      :desc => "A space-separated list of groups referencing gems to skip " +
+    desc "install", "Resolve and install dependencies for each appraisal"
+    method_option "jobs", aliases: "j", type: :numeric, default: 1,
+      banner: "SIZE",
+      desc: "Install gems in parallel using the given number of workers."
+    method_option "retry", type: :numeric, default: 1,
+      desc: "Retry network and git requests that have failed"
+    method_option "without", banner: "GROUP_NAMES",
+      desc: "A space-separated list of groups referencing gems to skip " +
         "during installation. Bundler will remember this option."
-    method_option "full-index", :type => :boolean,
-                                :desc => "Run bundle install with the " \
+    method_option "full-index", type: :boolean,
+                                desc: "Run bundle install with the " \
                                          "full-index argument."
     method_option "path", type: :string,
                           desc: "Install gems in the specified directory. " \
@@ -61,19 +65,19 @@ def install
       end
     end
 
-    desc 'generate', 'Generate a gemfile for each appraisal'
+    desc "generate", "Generate a gemfile for each appraisal"
     def generate
       AppraisalFile.each do |appraisal|
         appraisal.write_gemfile
       end
     end
 
-    desc 'clean', 'Remove all generated gemfiles and lockfiles from gemfiles folder'
+    desc "clean", "Remove all generated gemfiles and lockfiles from gemfiles folder"
     def clean
-      FileUtils.rm_f Dir['gemfiles/*.{gemfile,gemfile.lock}']
+      FileUtils.rm_f Dir["gemfiles/*.{gemfile,gemfile.lock}"]
     end
 
-    desc 'update [LIST_OF_GEMS]', 'Remove all generated gemfiles and lockfiles, resolve, and install dependencies again'
+    desc "update [LIST_OF_GEMS]", "Remove all generated gemfiles and lockfiles, resolve, and install dependencies again"
     def update(*gems)
       invoke :generate, []
 
@@ -82,7 +86,7 @@ def update(*gems)
       end
     end
 
-    desc 'list', 'List the names of the defined appraisals'
+    desc "list", "List the names of the defined appraisals"
     def list
       AppraisalFile.new.appraisals.each { |appraisal| puts appraisal.name }
     end
@@ -100,17 +104,17 @@ def method_missing(name, *args, &block)
       end
 
       if matching_appraisal
-        Command.new(args, :gemfile => matching_appraisal.gemfile_path).run
+        Command.new(args, gemfile: matching_appraisal.gemfile_path).run
       else
         AppraisalFile.each do |appraisal|
-          Command.new(ARGV, :gemfile => appraisal.gemfile_path).run
+          Command.new(ARGV, gemfile: appraisal.gemfile_path).run
         end
       end
     end
 
     def self.strip_heredoc(string)
       indent = string.scan(/^[ \t]*(?=\S)/).min.size || 0
-      string.gsub(/^[ \t]{#{indent}}/, '')
+      string.gsub(/^[ \t]{#{indent}}/, "")
     end
   end
 end
diff --git a/lib/appraisal/command.rb b/lib/appraisal/command.rb
index 6de50162..facadfd9 100644
--- a/lib/appraisal/command.rb
+++ b/lib/appraisal/command.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "shellwords"
 
 module Appraisal
@@ -70,7 +72,7 @@ def command_starting_with_bundle(original_command)
       if command_starts_with_bundle?(original_command)
         original_command
       else
-        %w(bundle exec) + original_command
+        %w[bundle exec] + original_command
       end
     end
 
diff --git a/lib/appraisal/conditional.rb b/lib/appraisal/conditional.rb
index f0702c55..db15ff33 100644
--- a/lib/appraisal/conditional.rb
+++ b/lib/appraisal/conditional.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
 require "appraisal/utils"
 
diff --git a/lib/appraisal/customize.rb b/lib/appraisal/customize.rb
index 0de1a78e..20cb99ac 100644
--- a/lib/appraisal/customize.rb
+++ b/lib/appraisal/customize.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Appraisal
   class Customize
     def initialize(heading: nil, single_quotes: false)
@@ -25,7 +27,7 @@ def self.customize(heading, gemfile)
         lockfile: "#{gemfile.send('gemfile_name')}.lock",
         lockfile_path: gemfile.send("lockfile_path"),
         relative_gemfile_path: gemfile.relative_gemfile_path,
-        relative_lockfile_path: "#{gemfile.relative_gemfile_path}.lock",
+        relative_lockfile_path: "#{gemfile.relative_gemfile_path}.lock"
       )
     end
 
diff --git a/lib/appraisal/dependency.rb b/lib/appraisal/dependency.rb
index 1d61d6a5..37302ab8 100644
--- a/lib/appraisal/dependency.rb
+++ b/lib/appraisal/dependency.rb
@@ -1,4 +1,6 @@
-require 'appraisal/utils'
+# frozen_string_literal: true
+
+require "appraisal/utils"
 
 module Appraisal
   # Dependency on a gem and optional version requirements
@@ -43,7 +45,7 @@ def formatted_output(output_requirements)
     end
 
     def gem_name
-      %{gem "#{name}"}
+      %(gem "#{name}")
     end
 
     def no_requirements?
diff --git a/lib/appraisal/dependency_list.rb b/lib/appraisal/dependency_list.rb
index cfdf36ea..9b6fb8d9 100644
--- a/lib/appraisal/dependency_list.rb
+++ b/lib/appraisal/dependency_list.rb
@@ -1,10 +1,12 @@
-require 'appraisal/dependency'
+# frozen_string_literal: true
+
+require "appraisal/dependency"
 require "set"
 
 module Appraisal
   class DependencyList
     def initialize
-      @dependencies = Hash.new
+      @dependencies = {}
       @removed_dependencies = Set.new
     end
 
diff --git a/lib/appraisal/errors.rb b/lib/appraisal/errors.rb
index d4005a5c..3475aff6 100644
--- a/lib/appraisal/errors.rb
+++ b/lib/appraisal/errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Appraisal
   # Raises when Appraisal is unable to locate Appraisals file in the current directory.
   class AppraisalsNotFound < StandardError
diff --git a/lib/appraisal/gemfile.rb b/lib/appraisal/gemfile.rb
index 3fbe7572..bfbb4580 100644
--- a/lib/appraisal/gemfile.rb
+++ b/lib/appraisal/gemfile.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
 
 module Appraisal
diff --git a/lib/appraisal/gemspec.rb b/lib/appraisal/gemspec.rb
index be09ccea..8c4d6a0a 100644
--- a/lib/appraisal/gemspec.rb
+++ b/lib/appraisal/gemspec.rb
@@ -1,4 +1,6 @@
-require 'appraisal/utils'
+# frozen_string_literal: true
+
+require "appraisal/utils"
 
 module Appraisal
   class Gemspec
@@ -6,7 +8,7 @@ class Gemspec
 
     def initialize(options = {})
       @options = options
-      @options[:path] ||= '.'
+      @options[:path] ||= "."
     end
 
     def to_s
@@ -22,7 +24,7 @@ def for_dup
 
     def exported_options
       @options.merge(
-        :path => Utils.prefix_path(@options[:path])
+        path: Utils.prefix_path(@options[:path])
       )
     end
   end
diff --git a/lib/appraisal/git.rb b/lib/appraisal/git.rb
index 3f4db2fe..5849cca1 100644
--- a/lib/appraisal/git.rb
+++ b/lib/appraisal/git.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
-require 'appraisal/utils'
+require "appraisal/utils"
 
 module Appraisal
   class Git < BundlerDSL
diff --git a/lib/appraisal/group.rb b/lib/appraisal/group.rb
index 4d68449a..2327298c 100644
--- a/lib/appraisal/group.rb
+++ b/lib/appraisal/group.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
-require 'appraisal/utils'
+require "appraisal/utils"
 
 module Appraisal
   class Group < BundlerDSL
@@ -20,10 +22,10 @@ def for_dup
     private
 
     def formatted_output(output_dependencies)
-      <<-OUTPUT.strip
-group #{Utils.format_arguments(@group_names)} do
-#{output_dependencies}
-end
+      <<~OUTPUT.strip
+        group #{Utils.format_arguments(@group_names)} do
+        #{output_dependencies}
+        end
       OUTPUT
     end
   end
diff --git a/lib/appraisal/path.rb b/lib/appraisal/path.rb
index 918f7e97..f06d2737 100644
--- a/lib/appraisal/path.rb
+++ b/lib/appraisal/path.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
-require 'appraisal/utils'
+require "appraisal/utils"
 
 module Appraisal
   class Path < BundlerDSL
diff --git a/lib/appraisal/platform.rb b/lib/appraisal/platform.rb
index 390d3fc0..ad98ce1f 100644
--- a/lib/appraisal/platform.rb
+++ b/lib/appraisal/platform.rb
@@ -1,5 +1,7 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
-require 'appraisal/utils'
+require "appraisal/utils"
 
 module Appraisal
   class Platform < BundlerDSL
@@ -20,10 +22,10 @@ def for_dup
     private
 
     def formatted_output(output_dependencies)
-      <<-OUTPUT.strip
-platforms #{Utils.format_arguments(@platform_names)} do
-#{output_dependencies}
-end
+      <<~OUTPUT.strip
+        platforms #{Utils.format_arguments(@platform_names)} do
+        #{output_dependencies}
+        end
       OUTPUT
     end
   end
diff --git a/lib/appraisal/source.rb b/lib/appraisal/source.rb
index ab74458c..c5905617 100644
--- a/lib/appraisal/source.rb
+++ b/lib/appraisal/source.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "appraisal/bundler_dsl"
 require "appraisal/utils"
 
@@ -20,11 +22,11 @@ def for_dup
     private
 
     def formatted_output(output_dependencies)
-      <<-OUTPUT.strip
-source #{@source.inspect} do
-#{output_dependencies}
-end
-        OUTPUT
+      <<~OUTPUT.strip
+        source #{@source.inspect} do
+        #{output_dependencies}
+        end
+      OUTPUT
     end
   end
 end
diff --git a/lib/appraisal/task.rb b/lib/appraisal/task.rb
index d0629d37..5c649925 100644
--- a/lib/appraisal/task.rb
+++ b/lib/appraisal/task.rb
@@ -1,5 +1,7 @@
-require 'appraisal/appraisal_file'
-require 'rake/tasklib'
+# frozen_string_literal: true
+
+require "appraisal/appraisal_file"
+require "rake/tasklib"
 
 module Appraisal
   # Defines tasks for installing appraisal dependencies and running other tasks
@@ -11,21 +13,21 @@ def initialize
         task :gemfiles do
           warn "`rake appraisal:gemfile` task is deprecated and will be removed soon. " +
             "Please use `appraisal generate`."
-          exec 'bundle exec appraisal generate'
+          exec "bundle exec appraisal generate"
         end
 
         desc "DEPRECATED: Resolve and install dependencies for each appraisal"
         task :install do
           warn "`rake appraisal:install` task is deprecated and will be removed soon. " +
             "Please use `appraisal install`."
-          exec 'bundle exec appraisal install'
+          exec "bundle exec appraisal install"
         end
 
         desc "DEPRECATED: Remove all generated gemfiles from gemfiles/ folder"
         task :cleanup do
           warn "`rake appraisal:cleanup` task is deprecated and will be removed soon. " +
             "Please use `appraisal clean`."
-          exec 'bundle exec appraisal clean'
+          exec "bundle exec appraisal clean"
         end
 
         begin
@@ -48,7 +50,7 @@ def initialize
       end
 
       desc "Run the given task for all appraisals"
-      task :appraisal => "appraisal:all"
+      task appraisal: "appraisal:all"
     end
   end
 end
diff --git a/lib/appraisal/utils.rb b/lib/appraisal/utils.rb
index fc5b1049..40e6c31e 100644
--- a/lib/appraisal/utils.rb
+++ b/lib/appraisal/utils.rb
@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 module Appraisal
   # Contains methods for various operations
   module Utils
     def self.support_parallel_installation?
-      Gem::Version.create(Bundler::VERSION) >= Gem::Version.create('1.4.0.pre.1')
+      Gem::Version.create(Bundler::VERSION) >= Gem::Version.create("1.4.0.pre.1")
     end
 
     def self.format_string(object, enclosing_object = false)
@@ -15,7 +17,7 @@ def self.format_string(object, enclosing_object = false)
         if enclosing_object
           "{ #{items.join(', ')} }"
         else
-          items.join(', ')
+          items.join(", ")
         end
       else
         object.inspect
@@ -35,7 +37,7 @@ def self.format_hash_value(key, value)
 
     def self.format_arguments(arguments)
       unless arguments.empty?
-        arguments.map { |object| format_string(object, false) }.join(', ')
+        arguments.map { |object| format_string(object, false) }.join(", ")
       end
     end
 
@@ -53,10 +55,7 @@ def self.prefix_path(path)
     end
 
     def self.bundler_version
-      Gem::Specification.
-        detect { |spec| spec.name == "bundler" }.
-        version.
-        to_s
+      Gem::Specification.detect { |spec| spec.name == "bundler" }.version.to_s
     end
   end
 end
diff --git a/lib/appraisal/version.rb b/lib/appraisal/version.rb
index 5ed40d98..71f6c23e 100644
--- a/lib/appraisal/version.rb
+++ b/lib/appraisal/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Appraisal
   VERSION = "2.5.0".freeze
 end
diff --git a/spec/acceptance/appraisals_file_bundler_dsl_compatibility_spec.rb b/spec/acceptance/appraisals_file_bundler_dsl_compatibility_spec.rb
index d5deaf94..41e6cdd6 100644
--- a/spec/acceptance/appraisals_file_bundler_dsl_compatibility_spec.rb
+++ b/spec/acceptance/appraisals_file_bundler_dsl_compatibility_spec.rb
@@ -1,12 +1,14 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'Appraisals file Bundler DSL compatibility' do
-  it 'supports all Bundler DSL in Appraisals file' do
-    build_gems %w(bagel orange_juice milk waffle coffee ham
-                  sausage pancake rotten_egg mayonnaise)
-    build_git_gems %w(egg croissant pain_au_chocolat omelette)
+require "spec_helper"
 
-    build_gemfile <<-Gemfile
+RSpec.describe "Appraisals file Bundler DSL compatibility" do
+  it "supports all Bundler DSL in Appraisals file" do
+    build_gems %w[bagel orange_juice milk waffle coffee ham
+                  sausage pancake rotten_egg mayonnaise]
+    build_git_gems %w[egg croissant pain_au_chocolat omelette]
+
+    build_gemfile <<-GEMFILE
       source 'https://rubygems.org'
       git_source(:custom_git_source) { |repo| "../build/\#{repo}" }
       ruby RUBY_VERSION
@@ -45,9 +47,9 @@
       end
 
       gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise 'breakfast' do
         source 'http://some-other-source.com'
         ruby "2.3.0"
@@ -87,12 +89,12 @@
         gemspec
         gemspec :path => "sitepress"
       end
-    Appraisals
+    APPRAISALS
 
-    run 'bundle install --local'
-    run 'appraisal generate'
+    run "bundle install --local"
+    run "appraisal generate"
 
-    expect(content_of 'gemfiles/breakfast.gemfile').to eq <<-Gemfile.strip_heredoc
+    expect(content_of("gemfiles/breakfast.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
@@ -147,28 +149,28 @@
 
       gemspec :path => "../"
       gemspec :path => "../sitepress"
-    Gemfile
+    GEMFILE
   end
 
   it 'supports ruby file: ".ruby-version" DSL' do
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source 'https://rubygems.org'
 
       ruby RUBY_VERSION
 
       gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise 'ruby-version' do
         ruby file: ".ruby-version"
       end
-    Appraisals
+    APPRAISALS
 
-    run 'bundle install --local'
-    run 'appraisal generate'
+    run "bundle install --local"
+    run "appraisal generate"
 
-    expect(content_of 'gemfiles/ruby_version.gemfile').to eq <<-Gemfile.strip_heredoc
+    expect(content_of("gemfiles/ruby_version.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
@@ -176,6 +178,6 @@
       ruby({:file=>".ruby-version"})
 
       gem "appraisal", :path => #{PROJECT_ROOT.inspect}
-    Gemfile
+    GEMFILE
   end
 end
diff --git a/spec/acceptance/bundle_with_custom_path_spec.rb b/spec/acceptance/bundle_with_custom_path_spec.rb
index 77cba434..b0d2157b 100644
--- a/spec/acceptance/bundle_with_custom_path_spec.rb
+++ b/spec/acceptance/bundle_with_custom_path_spec.rb
@@ -1,37 +1,38 @@
+# frozen_string_literal: true
+
 require "spec_helper"
 
 RSpec.describe "Bundle with custom path" do
-  let(:gem_name) { 'rack' }
-  let(:path) { 'vendor/bundle' }
+  let(:gem_name) { "rack" }
+  let(:path) { "vendor/bundle" }
 
   shared_examples :gemfile_dependencies_are_satisfied do
-
-    it 'installs gems in the --path directory' do
-      build_gemfile <<-Gemfile
+    it "installs gems in the --path directory" do
+      build_gemfile <<-GEMFILE
         source "https://rubygems.org"
 
         gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
-      Gemfile
+      GEMFILE
 
-      build_appraisal_file <<-Appraisals
+      build_appraisal_file <<-APPRAISALS
         appraise "#{gem_name}" do
           gem '#{gem_name}'
         end
-      Appraisals
+      APPRAISALS
 
       run "bundle config set --local path #{path}"
       run "bundle install"
-      run 'bundle exec appraisal install'
+      run "bundle exec appraisal install"
 
-      installed_gem = Dir.glob("tmp/stage/#{path}/#{Gem.ruby_engine}/*/gems/*").
-                      map    { |path| path.split('/').last }.
-                      select { |gem| gem.include?(gem_name) }
+      installed_gem = Dir.glob("tmp/stage/#{path}/#{Gem.ruby_engine}/*/gems/*")
+                         .map    { |path| path.split("/").last }
+                         .select { |gem| gem.include?(gem_name) }
       expect(installed_gem).not_to be_empty
 
-      bundle_output = run 'bundle check'
+      bundle_output = run "bundle check"
       expect(bundle_output).to include("The Gemfile's dependencies are satisfied")
 
-      appraisal_output = run 'bundle exec appraisal install'
+      appraisal_output = run "bundle exec appraisal install"
       expect(appraisal_output).to include("The Gemfile's dependencies are satisfied")
 
       run "bundle config unset --local path"
@@ -40,13 +41,13 @@
 
   include_examples :gemfile_dependencies_are_satisfied
 
-  context 'when already installed in vendor/another' do
+  context "when already installed in vendor/another" do
     before do
-      build_gemfile <<-Gemfile
+      build_gemfile <<-GEMFILE
         source "https://rubygems.org"
 
         gem '#{gem_name}'
-      Gemfile
+      GEMFILE
 
       run "bundle config set --local path vendor/another"
       run "bundle install"
diff --git a/spec/acceptance/bundle_without_spec.rb b/spec/acceptance/bundle_without_spec.rb
index 484c804f..7eb1b71f 100644
--- a/spec/acceptance/bundle_without_spec.rb
+++ b/spec/acceptance/bundle_without_spec.rb
@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 require "spec_helper"
 
 RSpec.describe "Bundler without flag" do
   it "passes --without flag to Bundler on install" do
-    build_gems %w(pancake orange_juice waffle coffee sausage soda)
+    build_gems %w[pancake orange_juice waffle coffee sausage soda]
 
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source "https://rubygems.org"
 
       gem "pancake"
@@ -15,9 +17,9 @@
       end
 
       gem "appraisal", :path => #{PROJECT_ROOT.inspect}
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise "breakfast" do
         gem "waffle"
 
@@ -33,7 +35,7 @@
           gem "soda"
         end
       end
-    Appraisals
+    APPRAISALS
 
     run "bundle install --local"
     run "bundle config set --local without 'drinks'"
diff --git a/spec/acceptance/cli/clean_spec.rb b/spec/acceptance/cli/clean_spec.rb
index a8e19bfc..7eed158c 100644
--- a/spec/acceptance/cli/clean_spec.rb
+++ b/spec/acceptance/cli/clean_spec.rb
@@ -1,20 +1,22 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal clean' do
-  it 'remove all gemfiles from gemfiles directory' do
-    build_appraisal_file <<-Appraisal
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal clean" do
+  it "remove all gemfiles from gemfiles directory" do
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal install'
-    write_file 'gemfiles/non_related_file', ''
+    run "appraisal install"
+    write_file "gemfiles/non_related_file", ""
 
-    run 'appraisal clean'
+    run "appraisal clean"
 
-    expect(file 'gemfiles/1.0.0.gemfile').not_to be_exists
-    expect(file 'gemfiles/1.0.0.gemfile.lock').not_to be_exists
-    expect(file 'gemfiles/non_related_file').to be_exists
+    expect(file("gemfiles/1.0.0.gemfile")).not_to be_exists
+    expect(file("gemfiles/1.0.0.gemfile.lock")).not_to be_exists
+    expect(file("gemfiles/non_related_file")).to be_exists
   end
 end
diff --git a/spec/acceptance/cli/generate_spec.rb b/spec/acceptance/cli/generate_spec.rb
index af5f65ea..285fc215 100644
--- a/spec/acceptance/cli/generate_spec.rb
+++ b/spec/acceptance/cli/generate_spec.rb
@@ -1,14 +1,16 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal generate' do
-  it 'generates the gemfiles' do
-    build_gemfile <<-Gemfile
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal generate" do
+  it "generates the gemfiles" do
+    build_gemfile <<-GEMFILE
       source "https://rubygems.org"
 
       gem "appraisal", :path => "#{PROJECT_ROOT}"
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisal
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
@@ -16,19 +18,19 @@
       appraise '1.1.0' do
         gem 'dummy', '1.1.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal generate'
+    run "appraisal generate"
 
-    expect(file 'gemfiles/1.0.0.gemfile').to be_exists
-    expect(file 'gemfiles/1.1.0.gemfile').to be_exists
-    expect(content_of 'gemfiles/1.0.0.gemfile').to eq <<-gemfile.strip_heredoc
+    expect(file("gemfiles/1.0.0.gemfile")).to be_exists
+    expect(file("gemfiles/1.1.0.gemfile")).to be_exists
+    expect(content_of("gemfiles/1.0.0.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
 
       gem "appraisal", :path => "#{PROJECT_ROOT}"
       gem "dummy", "1.0.0"
-    gemfile
+    GEMFILE
   end
 end
diff --git a/spec/acceptance/cli/help_spec.rb b/spec/acceptance/cli/help_spec.rb
index 56a8dded..da99f7a3 100644
--- a/spec/acceptance/cli/help_spec.rb
+++ b/spec/acceptance/cli/help_spec.rb
@@ -1,24 +1,26 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal help' do
-  it 'prints usage along with commands, and list of appraisals' do
-    build_appraisal_file <<-Appraisal
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal help" do
+  it "prints usage along with commands, and list of appraisals" do
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    output = run 'appraisal help'
+    output = run "appraisal help"
 
-    expect(output).to include 'Usage:'
-    expect(output).to include 'appraisal [APPRAISAL_NAME] EXTERNAL_COMMAND'
-    expect(output).to include '1.0.0'
+    expect(output).to include "Usage:"
+    expect(output).to include "appraisal [APPRAISAL_NAME] EXTERNAL_COMMAND"
+    expect(output).to include "1.0.0"
   end
 
-  it 'prints out usage even Appraisals file does not exist' do
-    output = run 'appraisal help'
+  it "prints out usage even Appraisals file does not exist" do
+    output = run "appraisal help"
 
-    expect(output).to include 'Usage:'
-    expect(output).not_to include 'Unable to locate'
+    expect(output).to include "Usage:"
+    expect(output).not_to include "Unable to locate"
   end
 end
diff --git a/spec/acceptance/cli/install_spec.rb b/spec/acceptance/cli/install_spec.rb
index 00d910df..09dcc106 100644
--- a/spec/acceptance/cli/install_spec.rb
+++ b/spec/acceptance/cli/install_spec.rb
@@ -1,14 +1,16 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal install' do
-  it 'raises error when there is no Appraisals file' do
-    output = run 'appraisal install 2>&1', false
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal install" do
+  it "raises error when there is no Appraisals file" do
+    output = run "appraisal install 2>&1", false
 
     expect(output).to include "Unable to locate 'Appraisals' file"
   end
 
-  it 'installs the dependencies' do
-    build_appraisal_file <<-Appraisal
+  it "installs the dependencies" do
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
@@ -16,28 +18,27 @@
       appraise '1.1.0' do
         gem 'dummy', '1.1.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal install'
+    run "appraisal install"
 
-    expect(file 'gemfiles/1.0.0.gemfile.lock').to be_exists
-    expect(file 'gemfiles/1.1.0.gemfile.lock').to be_exists
+    expect(file("gemfiles/1.0.0.gemfile.lock")).to be_exists
+    expect(file("gemfiles/1.1.0.gemfile.lock")).to be_exists
   end
 
-  it 'relativize directory in gemfile.lock' do
+  it "relativize directory in gemfile.lock" do
     build_gemspec
     add_gemspec_to_gemfile
 
-    build_appraisal_file <<-Appraisal
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal install'
+    run "appraisal install"
 
-    expect(content_of("gemfiles/1.0.0.gemfile.lock")).
-      not_to include(current_directory)
+    expect(content_of("gemfiles/1.0.0.gemfile.lock")).not_to include(current_directory)
   end
 
   it "does not relativize directory of uris in gemfile.lock" do
@@ -56,39 +57,30 @@
 
     run "appraisal install"
 
-    expect(content_of("gemfiles/1.0.0.gemfile.lock")).
-      to include("file://#{uri_dummy_path}")
+    expect(content_of("gemfiles/1.0.0.gemfile.lock")).to include("file://#{uri_dummy_path}")
   end
 
-  context 'with job size', :parallel => true do
+  context "with job size", parallel: true do
     before do
-      build_appraisal_file <<-Appraisal
+      build_appraisal_file <<-APPRAISAL
         appraise '1.0.0' do
           gem 'dummy', '1.0.0'
         end
-      Appraisal
+      APPRAISAL
     end
 
-    it 'accepts --jobs option to set job size' do
-      output = run 'appraisal install --jobs=2'
+    it "accepts --jobs option to set job size" do
+      output = run "appraisal install --jobs=2"
 
-      expect(output).to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=2"
-      )
+      expect(output).to include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=2")
     end
 
-    it 'ignores --jobs option if the job size is less than or equal to 1' do
-      output = run 'appraisal install --jobs=0'
-
-      expect(output).to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}'"
-      )
-      expect(output).not_to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=0"
-      )
-      expect(output).not_to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=1"
-      )
+    it "ignores --jobs option if the job size is less than or equal to 1" do
+      output = run "appraisal install --jobs=0"
+
+      expect(output).to     include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}'")
+      expect(output).not_to include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=0")
+      expect(output).not_to include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --jobs=1")
     end
   end
 
@@ -104,10 +96,7 @@
     it "accepts --full-index option to pull the full RubyGems index" do
       output = run("appraisal install --full-index")
 
-      expect(output).to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' " \
-        "--retry 1 --full-index true"
-      )
+      expect(output).to include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --retry 1 --full-index true")
     end
   end
 
@@ -123,10 +112,7 @@
     it "accepts --path option to specify the location to install gems into" do
       output = run("appraisal install --path vendor/appraisal")
 
-      expect(output).to include(
-        "bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' " \
-        "--path #{file('vendor/appraisal')} --retry 1",
-      )
+      expect(output).to include("bundle install --gemfile='#{file('gemfiles/1.0.0.gemfile')}' --path #{file('vendor/appraisal')} --retry 1")
     end
   end
 end
diff --git a/spec/acceptance/cli/list_spec.rb b/spec/acceptance/cli/list_spec.rb
index 4374db4b..917712ee 100644
--- a/spec/acceptance/cli/list_spec.rb
+++ b/spec/acceptance/cli/list_spec.rb
@@ -1,8 +1,10 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal list' do
-  it 'prints list of appraisals' do
-    build_appraisal_file <<-Appraisal
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal list" do
+  it "prints list of appraisals" do
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
@@ -12,16 +14,16 @@
       appraise '1.1.0' do
         gem 'dummy', '1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    output = run 'appraisal list'
+    output = run "appraisal list"
 
     expect(output).to eq("1.0.0\n2.0.0\n1.1.0\n")
   end
 
-  it 'prints nothing if there are no appraisals in the file' do
-    build_appraisal_file ''
-    output = run 'appraisal list'
+  it "prints nothing if there are no appraisals in the file" do
+    build_appraisal_file ""
+    output = run "appraisal list"
 
     expect(output.length).to eq(0)
   end
diff --git a/spec/acceptance/cli/run_spec.rb b/spec/acceptance/cli/run_spec.rb
index 91f01f4f..6bfcfd8c 100644
--- a/spec/acceptance/cli/run_spec.rb
+++ b/spec/acceptance/cli/run_spec.rb
@@ -1,8 +1,10 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI appraisal (with arguments)' do
+require "spec_helper"
+
+RSpec.describe "CLI appraisal (with arguments)" do
   before do
-    build_appraisal_file <<-Appraisal
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
@@ -10,47 +12,47 @@
       appraise '1.1.0' do
         gem 'dummy', '1.1.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal install'
-    write_file 'test.rb', 'puts "Running: #{$dummy_version}"'
-    write_file 'test with spaces.rb', 'puts "Running: #{$dummy_version}"'
+    run "appraisal install"
+    write_file "test.rb", 'puts "Running: #{$dummy_version}"'
+    write_file "test with spaces.rb", 'puts "Running: #{$dummy_version}"'
   end
 
-  it 'sets APPRAISAL_INITIALIZED environment variable' do
-    write_file 'test.rb', <<-TEST_FILE.strip_heredoc
+  it "sets APPRAISAL_INITIALIZED environment variable" do
+    write_file "test.rb", <<-TEST_FILE.strip_heredoc
       if ENV['APPRAISAL_INITIALIZED']
         puts "Appraisal initialized!"
       end
     TEST_FILE
 
-    output = run 'appraisal 1.0.0 ruby -rbundler/setup -rdummy test.rb'
-    expect(output).to include 'Appraisal initialized!'
+    output = run "appraisal 1.0.0 ruby -rbundler/setup -rdummy test.rb"
+    expect(output).to include "Appraisal initialized!"
   end
 
-  context 'with appraisal name' do
-    it 'runs the given command against a correct versions of dependency' do
-      output = run 'appraisal 1.0.0 ruby -rbundler/setup -rdummy test.rb'
+  context "with appraisal name" do
+    it "runs the given command against a correct versions of dependency" do
+      output = run "appraisal 1.0.0 ruby -rbundler/setup -rdummy test.rb"
 
-      expect(output).to include 'Running: 1.0.0'
-      expect(output).not_to include 'Running: 1.1.0'
+      expect(output).to include "Running: 1.0.0"
+      expect(output).not_to include "Running: 1.1.0"
     end
   end
 
-  context 'without appraisal name' do
-    it 'runs the given command against all versions of dependency' do
-      output = run 'appraisal ruby -rbundler/setup -rdummy test.rb'
+  context "without appraisal name" do
+    it "runs the given command against all versions of dependency" do
+      output = run "appraisal ruby -rbundler/setup -rdummy test.rb"
 
-      expect(output).to include 'Running: 1.0.0'
-      expect(output).to include 'Running: 1.1.0'
+      expect(output).to include "Running: 1.0.0"
+      expect(output).to include "Running: 1.1.0"
     end
   end
 
-  context 'when one of the arguments contains spaces' do
-    it 'preserves those spaces' do
+  context "when one of the arguments contains spaces" do
+    it "preserves those spaces" do
       command = 'appraisal 1.0.0 ruby -rbundler/setup -rdummy "test with spaces.rb"'
       output = run(command)
-      expect(output).to include 'Running: 1.0.0'
+      expect(output).to include "Running: 1.0.0"
     end
   end
 end
diff --git a/spec/acceptance/cli/update_spec.rb b/spec/acceptance/cli/update_spec.rb
index 262a1451..8929c89c 100644
--- a/spec/acceptance/cli/update_spec.rb
+++ b/spec/acceptance/cli/update_spec.rb
@@ -1,19 +1,21 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI', 'appraisal update' do
+require "spec_helper"
+
+RSpec.describe "CLI", "appraisal update" do
   before do
-    build_gem 'dummy2', '1.0.0'
+    build_gem "dummy2", "1.0.0"
 
-    build_appraisal_file <<-Appraisal
+    build_appraisal_file <<-APPRAISAL
       appraise 'dummy' do
         gem 'dummy', '~> 1.0.0'
         gem 'dummy2', '~> 1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal install'
-    build_gem 'dummy', '1.0.1'
-    build_gem 'dummy2', '1.0.1'
+    run "appraisal install"
+    build_gem "dummy", "1.0.1"
+    build_gem "dummy2", "1.0.1"
   end
 
   after do
@@ -23,22 +25,22 @@
     end
   end
 
-  context 'with no arguments' do
-    it 'updates all the gems' do
-      output = run 'appraisal update'
+  context "with no arguments" do
+    it "updates all the gems" do
+      output = run "appraisal update"
 
       expect(output).to include("gemfiles/dummy.gemfile bundle update")
-      expect(content_of 'gemfiles/dummy.gemfile.lock').to include 'dummy (1.0.1)'
-      expect(content_of 'gemfiles/dummy.gemfile.lock').to include 'dummy2 (1.0.1)'
+      expect(content_of("gemfiles/dummy.gemfile.lock")).to include "dummy (1.0.1)"
+      expect(content_of("gemfiles/dummy.gemfile.lock")).to include "dummy2 (1.0.1)"
     end
   end
 
-  context 'with a list of gems' do
-    it 'only updates specified gems' do
-      run 'appraisal update dummy'
+  context "with a list of gems" do
+    it "only updates specified gems" do
+      run "appraisal update dummy"
 
-      expect(content_of 'gemfiles/dummy.gemfile.lock').to include 'dummy (1.0.1)'
-      expect(content_of 'gemfiles/dummy.gemfile.lock').to include 'dummy2 (1.0.0)'
+      expect(content_of("gemfiles/dummy.gemfile.lock")).to include "dummy (1.0.1)"
+      expect(content_of("gemfiles/dummy.gemfile.lock")).to include "dummy2 (1.0.0)"
     end
   end
 end
diff --git a/spec/acceptance/cli/version_spec.rb b/spec/acceptance/cli/version_spec.rb
index 5840a0d1..e47a6548 100644
--- a/spec/acceptance/cli/version_spec.rb
+++ b/spec/acceptance/cli/version_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "spec_helper"
 
 RSpec.describe "CLI", "appraisal version" do
diff --git a/spec/acceptance/cli/with_no_arguments_spec.rb b/spec/acceptance/cli/with_no_arguments_spec.rb
index 82626cb5..4a04e64a 100644
--- a/spec/acceptance/cli/with_no_arguments_spec.rb
+++ b/spec/acceptance/cli/with_no_arguments_spec.rb
@@ -1,16 +1,18 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'CLI appraisal (with no arguments)' do
-  it 'runs install command' do
-    build_appraisal_file <<-Appraisal
+require "spec_helper"
+
+RSpec.describe "CLI appraisal (with no arguments)" do
+  it "runs install command" do
+    build_appraisal_file <<-APPRAISAL
       appraise '1.0.0' do
         gem 'dummy', '1.0.0'
       end
-    Appraisal
+    APPRAISAL
 
-    run 'appraisal'
+    run "appraisal"
 
-    expect(file 'gemfiles/1.0.0.gemfile').to be_exists
-    expect(file 'gemfiles/1.0.0.gemfile.lock').to be_exists
+    expect(file("gemfiles/1.0.0.gemfile")).to be_exists
+    expect(file("gemfiles/1.0.0.gemfile.lock")).to be_exists
   end
 end
diff --git a/spec/acceptance/gemfile_dsl_compatibility_spec.rb b/spec/acceptance/gemfile_dsl_compatibility_spec.rb
index 7a6baa64..2a9dcac3 100644
--- a/spec/acceptance/gemfile_dsl_compatibility_spec.rb
+++ b/spec/acceptance/gemfile_dsl_compatibility_spec.rb
@@ -1,12 +1,14 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'Gemfile DSL compatibility' do
-  it 'supports all Bundler DSL in Gemfile' do
-    build_gems %w(bacon orange_juice waffle)
-    build_git_gem 'egg'
+require "spec_helper"
+
+RSpec.describe "Gemfile DSL compatibility" do
+  it "supports all Bundler DSL in Gemfile" do
+    build_gems %w[bacon orange_juice waffle]
+    build_git_gem "egg"
     build_gemspec
 
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source "https://rubygems.org"
       ruby RUBY_VERSION
 
@@ -29,9 +31,9 @@
       gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
 
       gemspec
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise "japanese" do
         gem "rice"
         gem "miso_soup"
@@ -40,12 +42,12 @@
       appraise "english" do
         gem "bread"
       end
-    Appraisals
+    APPRAISALS
 
-    run 'bundle install --local'
-    run 'appraisal generate'
+    run "bundle install --local"
+    run "appraisal generate"
 
-    expect(content_of 'gemfiles/japanese.gemfile').to eq <<-Gemfile.strip_heredoc
+    expect(content_of("gemfiles/japanese.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
@@ -73,9 +75,9 @@
       end
 
       gemspec :path => "../"
-    Gemfile
+    GEMFILE
 
-    expect(content_of 'gemfiles/english.gemfile').to eq <<-Gemfile.strip_heredoc
+    expect(content_of("gemfiles/english.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
@@ -102,7 +104,7 @@
       end
 
       gemspec :path => "../"
-    Gemfile
+    GEMFILE
   end
 
   it "merges gem requirements" do
@@ -110,14 +112,14 @@
     build_gem "bacon", "1.1.0"
     build_gem "bacon", "1.2.0"
 
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source "https://rubygems.org"
 
       gem "appraisal", :path => #{PROJECT_ROOT.inspect}
       gem "bacon", "1.2.0"
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise "1.0.0" do
         gem "bacon", "1.0.0"
       end
@@ -129,21 +131,21 @@
       appraise "1.2.0" do
         gem "bacon", "1.2.0"
       end
-    Appraisals
+    APPRAISALS
 
-    run 'bundle install --local'
-    run 'appraisal generate'
+    run "bundle install --local"
+    run "appraisal generate"
 
-    expect(content_of "gemfiles/1.0.0.gemfile").to include('gem "bacon", "1.0.0"')
-    expect(content_of "gemfiles/1.1.0.gemfile").to include('gem "bacon", "1.1.0"')
-    expect(content_of "gemfiles/1.2.0.gemfile").to include('gem "bacon", "1.2.0"')
+    expect(content_of("gemfiles/1.0.0.gemfile")).to include('gem "bacon", "1.0.0"')
+    expect(content_of("gemfiles/1.1.0.gemfile")).to include('gem "bacon", "1.1.0"')
+    expect(content_of("gemfiles/1.2.0.gemfile")).to include('gem "bacon", "1.2.0"')
   end
 
   it "supports gemspec in the group block" do
     build_gem "bacon", "1.0.0"
     build_gemspec
 
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source "https://rubygems.org"
 
       gem "appraisal", :path => #{PROJECT_ROOT.inspect}
@@ -151,18 +153,18 @@
       group :plugin do
         gemspec
       end
-    Gemfile
+    GEMFILE
 
-    build_appraisal_file <<-Appraisals
+    build_appraisal_file <<-APPRAISALS
       appraise "1.0.0" do
         gem "bacon", "1.0.0"
       end
-    Appraisals
+    APPRAISALS
 
     run "bundle install --local"
     run "appraisal generate"
 
-    expect(content_of "gemfiles/1.0.0.gemfile").to eq <<-gemfile.strip_heredoc
+    expect(content_of("gemfiles/1.0.0.gemfile")).to eq <<-GEMFILE.strip_heredoc
       # This file was generated by Appraisal
 
       source "https://rubygems.org"
@@ -173,6 +175,6 @@
       group :plugin do
         gemspec :path => "../"
       end
-    gemfile
+    GEMFILE
   end
 end
diff --git a/spec/acceptance/gemspec_spec.rb b/spec/acceptance/gemspec_spec.rb
index eed13b24..d85fdf08 100644
--- a/spec/acceptance/gemspec_spec.rb
+++ b/spec/acceptance/gemspec_spec.rb
@@ -1,57 +1,59 @@
-require 'spec_helper'
+# frozen_string_literal: true
 
-RSpec.describe 'Gemspec' do
+require "spec_helper"
+
+RSpec.describe "Gemspec" do
   before do
     build_appraisal_file
     build_rakefile
   end
 
-  it 'supports gemspec syntax with default options' do
+  it "supports gemspec syntax with default options" do
     build_gemspec
 
-    write_file 'Gemfile', <<-Gemfile
+    write_file "Gemfile", <<-GEMFILE
       source "https://rubygems.org"
 
       gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
 
       gemspec
-    Gemfile
+    GEMFILE
 
-    run 'bundle install --local'
-    run 'appraisal install'
-    output = run 'appraisal rake version'
+    run "bundle install --local"
+    run "appraisal install"
+    output = run "appraisal rake version"
 
-    expect(output).to include 'Loaded 1.1.0'
+    expect(output).to include "Loaded 1.1.0"
   end
 
-  it 'supports gemspec syntax with path option' do
-    build_gemspec 'specdir'
+  it "supports gemspec syntax with path option" do
+    build_gemspec "specdir"
 
-    write_file 'Gemfile', <<-Gemfile
+    write_file "Gemfile", <<-GEMFILE
       source "https://rubygems.org"
 
       gem 'appraisal', :path => #{PROJECT_ROOT.inspect}
 
       gemspec :path => './specdir'
-    Gemfile
+    GEMFILE
 
-    run 'bundle install --local'
-    run 'appraisal install'
-    output = run 'appraisal rake version'
+    run "bundle install --local"
+    run "appraisal install"
+    output = run "appraisal rake version"
 
-    expect(output).to include 'Loaded 1.1.0'
+    expect(output).to include "Loaded 1.1.0"
   end
 
   def build_appraisal_file
-    super <<-Appraisals
+    super <<-APPRAISALS
       appraise 'stock' do
         gem 'rake'
       end
-    Appraisals
+    APPRAISALS
   end
 
   def build_rakefile
-    write_file 'Rakefile', <<-rakefile
+    write_file "Rakefile", <<-RAKEFILE
       require 'rubygems'
       require 'bundler/setup'
       require 'appraisal'
@@ -60,13 +62,13 @@ def build_rakefile
         require 'dummy'
         puts "Loaded \#{$dummy_version}"
       end
-    rakefile
+    RAKEFILE
   end
 
-  def build_gemspec(path = '.')
+  def build_gemspec(path = ".")
     Dir.mkdir("tmp/stage/#{path}") rescue nil
 
-    write_file File.join(path, 'gemspec_project.gemspec'), <<-gemspec
+    write_file File.join(path, "gemspec_project.gemspec"), <<-GEMSPEC
       Gem::Specification.new do |s|
         s.name = 'gemspec_project'
         s.version = '0.1'
@@ -75,6 +77,6 @@ def build_gemspec(path = '.')
 
         s.add_development_dependency('dummy', '1.1.0')
       end
-    gemspec
+    GEMSPEC
   end
 end
diff --git a/spec/appraisal/appraisal_file_spec.rb b/spec/appraisal/appraisal_file_spec.rb
index 878526e8..8b583ea8 100644
--- a/spec/appraisal/appraisal_file_spec.rb
+++ b/spec/appraisal/appraisal_file_spec.rb
@@ -1,10 +1,12 @@
-require 'spec_helper'
-require 'appraisal/appraisal_file'
+# frozen_string_literal: true
+
+require "spec_helper"
+require "appraisal/appraisal_file"
 
 # Requiring this to make the test pass on Rubinius 2.2.5
 # https://github.com/rubinius/rubinius/issues/2934
-require 'rspec/matchers/composable'
-require 'rspec/matchers/built_in/raise_error'
+require "rspec/matchers/composable"
+require "rspec/matchers/built_in/raise_error"
 
 RSpec.describe Appraisal::AppraisalFile do
   it "complains when no Appraisals file is found" do
diff --git a/spec/appraisal/appraisal_spec.rb b/spec/appraisal/appraisal_spec.rb
index b4f04298..d68bfd57 100644
--- a/spec/appraisal/appraisal_spec.rb
+++ b/spec/appraisal/appraisal_spec.rb
@@ -1,6 +1,8 @@
-require 'spec_helper'
-require 'appraisal/appraisal'
-require 'tempfile'
+# frozen_string_literal: true
+
+require "spec_helper"
+require "appraisal/appraisal"
+require "tempfile"
 
 RSpec.describe Appraisal::Appraisal do
   it "converts spaces to underscores in the gemfile path" do
@@ -85,50 +87,45 @@
     end
   end
 
-  context 'parallel installation' do
+  context "parallel installation" do
     include StreamHelpers
 
     before do
-      @appraisal = Appraisal::Appraisal.new('fake', 'fake')
+      @appraisal = Appraisal::Appraisal.new("fake", "fake")
       allow(@appraisal).to receive(:gemfile_path).and_return("/home/test/test directory")
-      allow(@appraisal).to receive(:project_root).
-        and_return(Pathname.new("/home/test"))
-      allow(Appraisal::Command).to receive(:new).and_return(double(:run => true))
+      allow(@appraisal).to receive(:project_root).and_return(Pathname.new("/home/test"))
+      allow(Appraisal::Command).to receive(:new).and_return(double(run: true))
     end
 
-    it 'runs single install command on Bundler < 1.4.0' do
-      stub_const('Bundler::VERSION', '1.3.0')
+    it "runs single install command on Bundler < 1.4.0" do
+      stub_const("Bundler::VERSION", "1.3.0")
 
       warning = capture(:stderr) do
         @appraisal.install("jobs" => 42)
       end
 
-      expect(Appraisal::Command).to have_received(:new).
-        with("#{bundle_check_command} || #{bundle_single_install_command}")
-      expect(warning).to include 'Please upgrade Bundler'
+      expect(Appraisal::Command).to have_received(:new).with("#{bundle_check_command} || #{bundle_single_install_command}")
+      expect(warning).to include "Please upgrade Bundler"
     end
 
-    it 'runs parallel install command on Bundler >= 1.4.0' do
-      stub_const('Bundler::VERSION', '1.4.0')
+    it "runs parallel install command on Bundler >= 1.4.0" do
+      stub_const("Bundler::VERSION", "1.4.0")
 
       @appraisal.install("jobs" => 42)
 
-      expect(Appraisal::Command).to have_received(:new).
-        with("#{bundle_check_command} || #{bundle_parallel_install_command}")
+      expect(Appraisal::Command).to have_received(:new).with("#{bundle_check_command} || #{bundle_parallel_install_command}")
     end
 
-    it 'runs install command with retries on Bundler' do
+    it "runs install command with retries on Bundler" do
       @appraisal.install("retry" => 3)
 
-      expect(Appraisal::Command).to have_received(:new).
-        with("#{bundle_check_command} || #{bundle_install_command_with_retries}")
+      expect(Appraisal::Command).to have_received(:new).with("#{bundle_check_command} || #{bundle_install_command_with_retries}")
     end
 
     it "runs install command with path on Bundler" do
       @appraisal.install("path" => "vendor/appraisal")
 
-      expect(Appraisal::Command).to have_received(:new).
-        with("#{bundle_check_command} || #{bundle_install_command_with_path}")
+      expect(Appraisal::Command).to have_received(:new).with("#{bundle_check_command} || #{bundle_install_command_with_path}")
     end
 
     def bundle_check_command
diff --git a/spec/appraisal/customize_spec.rb b/spec/appraisal/customize_spec.rb
index 8486a7e8..98e77f36 100644
--- a/spec/appraisal/customize_spec.rb
+++ b/spec/appraisal/customize_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "spec_helper"
 require "appraisal/appraisal"
 require "appraisal/customize"
@@ -62,8 +64,7 @@
       allow(appraisal).to receive(:gemfile_name).and_return(gemfile)
       allow(appraisal).to receive(:gemfile_path).and_return(gemfile_full_path)
       allow(appraisal).to receive(:lockfile_path).and_return(lockfile_full_path)
-      allow(appraisal).to receive(:relative_gemfile_path).
-        and_return(gemfile_relative_path)
+      allow(appraisal).to receive(:relative_gemfile_path).and_return(gemfile_relative_path)
     end
 
     it "returns nil if no heading is set" do
@@ -76,15 +77,15 @@
       expect(described_class.send(
                :customize,
                single_line_heading,
-               appraisal,
+               appraisal
              )).to eq(single_line_heading)
     end
 
     it "returns the heading with the appraisal name" do
       expect(described_class.send(
                :customize,
-               "Appraisal: %{appraisal}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Appraisal: %{appraisal}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Appraisal: #{appraisal_name}")
     end
 
@@ -92,47 +93,47 @@
       expect(described_class.send(
                :customize,
                "Gemfile: %{gemfile}", # rubocop:disable Style/FormatStringToken
-               appraisal,
+               appraisal
              )).to eq("Gemfile: #{gemfile}")
     end
 
     it "returns the heading with the gemfile path" do
       expect(described_class.send(
                :customize,
-               "Gemfile: %{gemfile_path}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Gemfile: %{gemfile_path}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Gemfile: #{gemfile_full_path}")
     end
 
     it "returns the heading with the lockfile name" do
       expect(described_class.send(
                :customize,
-               "Lockfile: %{lockfile}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Lockfile: %{lockfile}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Lockfile: #{lockfile}")
     end
 
     it "returns the heading with the lockfile path" do
       expect(described_class.send(
                :customize,
-               "Lockfile: %{lockfile_path}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Lockfile: %{lockfile_path}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Lockfile: #{lockfile_full_path}")
     end
 
     it "returns the heading with the relative gemfile path" do
       expect(described_class.send(
                :customize,
-               "Gemfile: %{relative_gemfile_path}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Gemfile: %{relative_gemfile_path}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Gemfile: #{gemfile_relative_path}")
     end
 
     it "returns the heading with the relative lockfile path" do
       expect(described_class.send(
                :customize,
-               "Gemfile: %{relative_lockfile_path}", # rubocop:disable Style/FormatStringToken, Metrics/LineLength
-               appraisal,
+               "Gemfile: %{relative_lockfile_path}", # rubocop:disable Style/FormatStringToken
+               appraisal
              )).to eq("Gemfile: #{lockfile_relative_path}")
     end
   end
diff --git a/spec/appraisal/dependency_list_spec.rb b/spec/appraisal/dependency_list_spec.rb
index ec80a1db..8b322984 100644
--- a/spec/appraisal/dependency_list_spec.rb
+++ b/spec/appraisal/dependency_list_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "spec_helper"
 require "appraisal/dependency_list"
 
diff --git a/spec/appraisal/gemfile_spec.rb b/spec/appraisal/gemfile_spec.rb
index 2785536c..666c07ba 100644
--- a/spec/appraisal/gemfile_spec.rb
+++ b/spec/appraisal/gemfile_spec.rb
@@ -1,27 +1,29 @@
-require 'spec_helper'
-require 'appraisal/gemfile'
-require 'active_support/core_ext/string/strip'
+# frozen_string_literal: true
+
+require "spec_helper"
+require "appraisal/gemfile"
+require "active_support/core_ext/string/strip"
 
 RSpec.describe Appraisal::Gemfile do
   include StreamHelpers
 
   it "supports gemfiles without sources" do
     gemfile = Appraisal::Gemfile.new
-    expect(gemfile.to_s.strip).to eq ''
+    expect(gemfile.to_s.strip).to eq ""
   end
 
   it "supports multiple sources" do
     gemfile = Appraisal::Gemfile.new
     gemfile.source "one"
     gemfile.source "two"
-    expect(gemfile.to_s.strip).to eq %{source "one"\nsource "two"}
+    expect(gemfile.to_s.strip).to eq %(source "one"\nsource "two")
   end
 
   it "ignores duplicate sources" do
     gemfile = Appraisal::Gemfile.new
     gemfile.source "one"
     gemfile.source "one"
-    expect(gemfile.to_s.strip).to eq %{source "one"}
+    expect(gemfile.to_s.strip).to eq %(source "one")
   end
 
   it "preserves dependency order" do
@@ -35,10 +37,10 @@
   it "supports symbol sources" do
     gemfile = Appraisal::Gemfile.new
     gemfile.source :one
-    expect(gemfile.to_s.strip).to eq %{source :one}
+    expect(gemfile.to_s.strip).to eq %(source :one)
   end
 
-  it 'supports group syntax' do
+  it "supports group syntax" do
     gemfile = Appraisal::Gemfile.new
 
     gemfile.group :development, :test do
@@ -84,7 +86,7 @@
     GEMFILE
   end
 
-  it 'supports platform syntax' do
+  it "supports platform syntax" do
     gemfile = Appraisal::Gemfile.new
 
     gemfile.platform :jruby do
@@ -226,7 +228,7 @@
     context "no contents" do
       it "shows empty string" do
         gemfile = Appraisal::Gemfile.new
-        expect(gemfile.to_s).to eq ''
+        expect(gemfile.to_s).to eq ""
       end
     end
 
@@ -251,26 +253,26 @@
   end
 
   context "relative path handling" do
-    before { stub_const('RUBY_VERSION', '2.3.0') }
+    before { stub_const("RUBY_VERSION", "2.3.0") }
 
     context "in :path option" do
       it "handles dot path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :path => "."
+        gemfile.gem "bacon", path: "."
 
         expect(gemfile.to_s).to eq %(gem "bacon", path: "../")
       end
 
       it "handles relative path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :path => "../bacon"
+        gemfile.gem "bacon", path: "../bacon"
 
         expect(gemfile.to_s).to eq %(gem "bacon", path: "../../bacon")
       end
 
       it "handles absolute path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :path => "/tmp"
+        gemfile.gem "bacon", path: "/tmp"
 
         expect(gemfile.to_s).to eq %(gem "bacon", path: "/tmp")
       end
@@ -279,31 +281,30 @@
     context "in :git option" do
       it "handles dot git path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :git => "."
+        gemfile.gem "bacon", git: "."
 
         expect(gemfile.to_s).to eq %(gem "bacon", git: "../")
       end
 
       it "handles relative git path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :git => "../bacon"
+        gemfile.gem "bacon", git: "../bacon"
 
         expect(gemfile.to_s).to eq %(gem "bacon", git: "../../bacon")
       end
 
       it "handles absolute git path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :git => "/tmp"
+        gemfile.gem "bacon", git: "/tmp"
 
         expect(gemfile.to_s).to eq %(gem "bacon", git: "/tmp")
       end
 
       it "handles git uri" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gem "bacon", :git => "git@github.com:bacon/bacon.git"
+        gemfile.gem "bacon", git: "git@github.com:bacon/bacon.git"
 
-        expect(gemfile.to_s).
-          to eq %(gem "bacon", git: "git@github.com:bacon/bacon.git")
+        expect(gemfile.to_s).to eq %(gem "bacon", git: "git@github.com:bacon/bacon.git")
       end
     end
 
@@ -315,11 +316,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           path "../" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
 
       it "handles relative path" do
@@ -329,11 +330,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           path "../../bacon" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
 
       it "handles absolute path" do
@@ -343,11 +344,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           path "/tmp" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
     end
 
@@ -359,11 +360,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           git "../" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
 
       it "handles relative git path" do
@@ -373,11 +374,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           git "../../bacon" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
 
       it "handles absolute git path" do
@@ -387,11 +388,11 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           git "/tmp" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
 
       it "handles git uri" do
@@ -401,18 +402,18 @@
           gem "bacon"
         end
 
-        expect(gemfile.to_s).to eq <<-gemfile.strip_heredoc.strip
+        expect(gemfile.to_s).to eq <<-GEMFILE.strip_heredoc.strip
           git "git@github.com:bacon/bacon.git" do
             gem "bacon"
           end
-        gemfile
+        GEMFILE
       end
     end
 
     context "in gemspec directive" do
       it "handles gemspec path" do
         gemfile = Appraisal::Gemfile.new
-        gemfile.gemspec :path => "."
+        gemfile.gemspec path: "."
 
         expect(gemfile.to_s).to eq %(gemspec path: "../")
       end
@@ -420,12 +421,12 @@
   end
 
   context "git_source support" do
-    before { stub_const('RUBY_VERSION', '2.3.0') }
+    before { stub_const("RUBY_VERSION", "2.3.0") }
 
     it "stores git_source declaration and apply it as git option" do
       gemfile = Appraisal::Gemfile.new
       gemfile.git_source(:custom_source) { |repo| "path/#{repo}" }
-      gemfile.gem "bacon", :custom_source => "bacon_pancake"
+      gemfile.gem "bacon", custom_source: "bacon_pancake"
 
       expect(gemfile.to_s).to eq %(gem "bacon", git: "../path/bacon_pancake")
     end
diff --git a/spec/appraisal/utils_spec.rb b/spec/appraisal/utils_spec.rb
index 0a1d2e92..04dfe910 100644
--- a/spec/appraisal/utils_spec.rb
+++ b/spec/appraisal/utils_spec.rb
@@ -1,34 +1,32 @@
-require 'spec_helper'
-require 'appraisal/utils'
+# frozen_string_literal: true
+
+require "spec_helper"
+require "appraisal/utils"
 
 RSpec.describe Appraisal::Utils do
-  describe '.format_string' do
+  describe ".format_string" do
     it "prints out a nice looking hash without brackets with new syntax" do
-      hash = { :foo => 'bar' }
+      hash = { foo: "bar" }
       expect(Appraisal::Utils.format_string(hash)).to eq('foo: "bar"')
 
-      hash = { 'baz' => { :ball => 'boo' }}
-      expect(Appraisal::Utils.format_string(hash)).
-        to eq('"baz" => { ball: "boo" }')
+      hash = { "baz" => { ball: "boo" } }
+      expect(Appraisal::Utils.format_string(hash)).to eq('"baz" => { ball: "boo" }')
     end
   end
 
-  describe '.format_arguments' do
-    before { stub_const('RUBY_VERSION', '2.3.0') }
+  describe ".format_arguments" do
+    before { stub_const("RUBY_VERSION", "2.3.0") }
 
-    it 'prints out arguments without enclosing square brackets' do
-      arguments = [:foo, { :bar => { :baz => 'ball' }}]
+    it "prints out arguments without enclosing square brackets" do
+      arguments = [:foo, { bar: { baz: "ball" } }]
 
-      expect(Appraisal::Utils.format_arguments(arguments)).to eq(
-        ':foo, bar: { baz: "ball" }'
-      )
+      expect(Appraisal::Utils.format_arguments(arguments)).to eq(':foo, bar: { baz: "ball" }')
     end
 
     it "returns nil if arguments is empty" do
       arguments = []
 
-      expect(Appraisal::Utils.format_arguments(arguments)).
-        to eq(nil)
+      expect(Appraisal::Utils.format_arguments(arguments)).to eq(nil)
     end
   end
 
@@ -45,25 +43,20 @@
       expect(Appraisal::Utils.prefix_path("/tmp")).to eq "/tmp"
     end
 
-    it "strips out './' from path"  do
-      expect(Appraisal::Utils.prefix_path("./tmp/./appraisal././")).
-        to eq "../tmp/appraisal./"
+    it "strips out './' from path" do
+      expect(Appraisal::Utils.prefix_path("./tmp/./appraisal././")).to eq "../tmp/appraisal./"
     end
 
     it "does not prefix Git uri" do
-      expect(Appraisal::Utils.prefix_path("git@github.com:bacon/bacon.git")).
-        to eq "git@github.com:bacon/bacon.git"
-      expect(Appraisal::Utils.prefix_path("git://github.com/bacon/bacon.git")).
-        to eq "git://github.com/bacon/bacon.git"
-      expect(
-        Appraisal::Utils.prefix_path("https://github.com/bacon/bacon.git")
-      ).to eq("https://github.com/bacon/bacon.git")
+      expect(Appraisal::Utils.prefix_path("git@github.com:bacon/bacon.git")).to eq "git@github.com:bacon/bacon.git"
+      expect(Appraisal::Utils.prefix_path("git://github.com/bacon/bacon.git")).to eq "git://github.com/bacon/bacon.git"
+      expect(Appraisal::Utils.prefix_path("https://github.com/bacon/bacon.git")).to eq("https://github.com/bacon/bacon.git")
     end
   end
 
   describe ".bundler_version" do
     it "returns the bundler version" do
-      bundler = double("Bundler", :name => "bundler", :version => "a.b.c")
+      bundler = double("Bundler", name: "bundler", version: "a.b.c")
       allow(Gem::Specification).to receive(:detect).and_return(bundler)
 
       version = Appraisal::Utils.bundler_version
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 249f049e..20b036de 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,9 +1,11 @@
-require 'rubygems'
-require 'bundler/setup'
+# frozen_string_literal: true
+
+require "rubygems"
+require "bundler/setup"
 require "./spec/support/acceptance_test_helpers"
 require "./spec/support/stream_helpers"
 
-PROJECT_ROOT = File.expand_path(File.join(File.dirname(__FILE__), '..')).freeze
+PROJECT_ROOT = File.expand_path(File.join(File.dirname(__FILE__), "..")).freeze
 TMP_GEM_ROOT = File.join(PROJECT_ROOT, "tmp", "bundler")
 TMP_GEM_BUILD = File.join(PROJECT_ROOT, "tmp", "build")
 ENV["APPRAISAL_UNDER_TEST"] = "1"
@@ -11,11 +13,11 @@
 RSpec.configure do |config|
   config.raise_errors_for_deprecations!
 
-  config.define_derived_metadata(:file_path => %r{spec\/acceptance\/}) do |metadata|
+  config.define_derived_metadata(file_path: %r{spec\/acceptance\/}) do |metadata|
     metadata[:type] = :acceptance
   end
 
-  config.include AcceptanceTestHelpers, :type => :acceptance
+  config.include AcceptanceTestHelpers, type: :acceptance
 
   # disable monkey patching
   # see: https://relishapp.com/rspec/rspec-core/v/3-8/docs/configuration/zero-monkey-patching-mode
diff --git a/spec/support/acceptance_test_helpers.rb b/spec/support/acceptance_test_helpers.rb
index 2b3f4216..52e0c60a 100644
--- a/spec/support/acceptance_test_helpers.rb
+++ b/spec/support/acceptance_test_helpers.rb
@@ -1,28 +1,30 @@
-require 'rspec/expectations/expectation_target'
-require 'active_support/core_ext/string/strip'
-require 'active_support/core_ext/string/filters'
-require 'active_support/concern'
-require 'appraisal/utils'
+# frozen_string_literal: true
+
+require "rspec/expectations/expectation_target"
+require "active_support/core_ext/string/strip"
+require "active_support/core_ext/string/filters"
+require "active_support/concern"
+require "appraisal/utils"
 require "./spec/support/dependency_helpers"
 
 module AcceptanceTestHelpers
   extend ActiveSupport::Concern
   include DependencyHelpers
 
-  BUNDLER_ENVIRONMENT_VARIABLES = %w(
+  BUNDLER_ENVIRONMENT_VARIABLES = %w[
     RUBYOPT
     BUNDLE_PATH
     BUNDLE_BIN_PATH
     BUNDLE_GEMFILE
     BUNDLER_SETUP
-  ).freeze
+  ].freeze
 
   included do
     metadata[:type] = :acceptance
 
-    before :parallel => true do
+    before parallel: true do
       unless Appraisal::Utils.support_parallel_installation?
-        pending 'This Bundler version does not support --jobs flag.'
+        pending "This Bundler version does not support --jobs flag."
       end
     end
 
@@ -44,7 +46,7 @@ module AcceptanceTestHelpers
   def save_environment_variables
     @original_environment_variables = {}
 
-    (BUNDLER_ENVIRONMENT_VARIABLES + %w(PATH)).each do |key|
+    (BUNDLER_ENVIRONMENT_VARIABLES + %w[PATH]).each do |key|
       @original_environment_variables[key] = ENV[key]
     end
   end
@@ -56,7 +58,7 @@ def unset_bundler_environment_variables
   end
 
   def add_binstub_path
-    ENV['PATH'] = "bin:#{ENV['PATH']}"
+    ENV["PATH"] = "bin:#{ENV['PATH']}"
   end
 
   def restore_environment_variables
@@ -66,28 +68,28 @@ def restore_environment_variables
   end
 
   def build_appraisal_file(content)
-    write_file 'Appraisals', content.strip_heredoc
+    write_file "Appraisals", content.strip_heredoc
   end
 
   def build_gemfile(content)
-    write_file 'Gemfile', content.strip_heredoc
+    write_file "Gemfile", content.strip_heredoc
   end
 
   def add_gemspec_to_gemfile
     in_test_directory do
-      File.open('Gemfile', 'a') { |file| file.puts 'gemspec' }
+      File.open("Gemfile", "a") { |file| file.puts "gemspec" }
     end
   end
 
   def build_gemspec
-    write_file "stage.gemspec", <<-gemspec
+    write_file "stage.gemspec", <<-GEMSPEC
       Gem::Specification.new do |s|
         s.name = 'stage'
         s.version = '0.1'
         s.summary = 'Awesome Gem!'
         s.authors = "Appraisal"
       end
-    gemspec
+    GEMSPEC
   end
 
   def content_of(path)
@@ -107,11 +109,11 @@ def be_exists
   private
 
   def current_directory
-    File.expand_path('tmp/stage')
+    File.expand_path("tmp/stage")
   end
 
   def write_file(filename, content)
-    in_test_directory { File.open(filename, 'w') { |file| file.puts content } }
+    in_test_directory { File.open(filename, "w") { |file| file.puts content } }
   end
 
   def cleanup_artifacts
@@ -121,8 +123,8 @@ def cleanup_artifacts
   def build_default_dummy_gems
     FileUtils.mkdir_p(TMP_GEM_ROOT)
 
-    build_gem 'dummy', '1.0.0'
-    build_gem 'dummy', '1.1.0'
+    build_gem "dummy", "1.0.0"
+    build_gem "dummy", "1.1.0"
   end
 
   def ensure_bundler_is_available
@@ -140,11 +142,11 @@ def ensure_bundler_is_available
   end
 
   def build_default_gemfile
-    build_gemfile <<-Gemfile
+    build_gemfile <<-GEMFILE
       source 'https://rubygems.org'
 
       gem 'appraisal', :path => '#{PROJECT_ROOT}'
-    Gemfile
+    GEMFILE
 
     run "bundle install --local"
     run "bundle binstubs --all"
@@ -165,10 +167,10 @@ def run(command, raise_on_error = true)
         end
 
         if raise_on_error && exitstatus != 0
-          raise RuntimeError, <<-error_message.strip_heredoc
+          raise RuntimeError, <<-ERROR_MESSAGE.strip_heredoc
             Command #{command.inspect} exited with status #{exitstatus}. Output:
             #{output.gsub(/^/, '  ')}
-          error_message
+          ERROR_MESSAGE
         end
       end
     end
diff --git a/spec/support/dependency_helpers.rb b/spec/support/dependency_helpers.rb
index 14cf1308..54752d20 100644
--- a/spec/support/dependency_helpers.rb
+++ b/spec/support/dependency_helpers.rb
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 module DependencyHelpers
-  def build_gem(gem_name, version = '1.0.0')
-    ENV['GEM_HOME'] = TMP_GEM_ROOT
+  def build_gem(gem_name, version = "1.0.0")
+    ENV["GEM_HOME"] = TMP_GEM_ROOT
 
     unless File.exist? "#{TMP_GEM_ROOT}/gems/#{gem_name}-#{version}"
       FileUtils.mkdir_p "#{TMP_GEM_BUILD}/#{gem_name}/lib"
@@ -9,8 +11,8 @@ def build_gem(gem_name, version = '1.0.0')
         gemspec = "#{gem_name}.gemspec"
         lib_file = "lib/#{gem_name}.rb"
 
-        File.open gemspec, 'w' do |file|
-          file.puts <<-gemspec
+        File.open gemspec, "w" do |file|
+          file.puts <<-GEMSPEC
             Gem::Specification.new do |s|
               s.name    = #{gem_name.inspect}
               s.version = #{version.inspect}
@@ -21,14 +23,14 @@ def build_gem(gem_name, version = '1.0.0')
               s.homepage = 'http://github.com/thoughtbot/#{gem_name}'
               s.required_ruby_version = '>= 2.3.0'
             end
-          gemspec
+          GEMSPEC
         end
 
-        File.open lib_file, 'w' do |file|
+        File.open lib_file, "w" do |file|
           file.puts "$#{gem_name}_version = '#{version}'"
         end
 
-        redirect = ENV['VERBOSE'] ? '' : '2>&1'
+        redirect = ENV["VERBOSE"] ? "" : "2>&1"
 
         puts "building gem: #{gem_name} #{version}" if ENV["VERBOSE"]
         `gem build #{gemspec} #{redirect}`
@@ -45,7 +47,7 @@ def build_gems(gems)
     gems.each { |gem| build_gem(gem) }
   end
 
-  def build_git_gem(gem_name, version = '1.0.0')
+  def build_git_gem(gem_name, version = "1.0.0")
     puts "building git gem: #{gem_name} #{version}" if ENV["VERBOSE"]
     build_gem gem_name, version
 
diff --git a/spec/support/stream_helpers.rb b/spec/support/stream_helpers.rb
index dfd7c353..ca0eb436 100644
--- a/spec/support/stream_helpers.rb
+++ b/spec/support/stream_helpers.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "tempfile"
 
 module StreamHelpers