diff --git a/Library/.rubocop.yml b/Library/.rubocop.yml
index d6dc0c4295..99de0d8a21 100644
--- a/Library/.rubocop.yml
+++ b/Library/.rubocop.yml
@@ -4,6 +4,8 @@ inherit_from:
 
 AllCops:
   TargetRubyVersion: 2.0
+  Include:
+    - '**/.simplecov'
   Exclude:
     - 'Homebrew/cask/**/*'
     - 'Homebrew/vendor/**/*'
diff --git a/Library/.rubocop_rules.yml b/Library/.rubocop_rules.yml
index cde3109303..95f8ae0a36 100644
--- a/Library/.rubocop_rules.yml
+++ b/Library/.rubocop_rules.yml
@@ -7,6 +7,14 @@ Style/StringLiterals:
 Style/StringLiteralsInInterpolation:
   EnforcedStyle: double_quotes
 
+# only for numbers >= 1_000_000
+Style/NumericLiterals:
+  MinDigits: 7
+
+# zero-prefixed octal literals are just too widely used (and mostly understood)
+Style/NumericLiteralPrefix:
+  EnforcedOctalStyle: zero_only
+
 # percent-x is allowed for multiline
 Style/CommandLiteral:
   EnforcedStyle: mixed
@@ -58,14 +66,6 @@ Lint/ParenthesesAsGroupedExpression:
 Style/EmptyLineBetweenDefs:
   AllowAdjacentOneLineDefs: true
 
-# port numbers and such tech stuff
-Style/NumericLiterals:
-  Enabled: false
-
-# zero-prefixed octal literals are just too widely used (and mostly understood)
-Style/NumericLiteralPrefix:
-  EnforcedOctalStyle: zero_only
-
 # consistency and readability when faced with string interpolation
 Style/PercentLiteralDelimiters:
   PreferredDelimiters:
@@ -93,15 +93,31 @@ Style/AlignParameters:
 
 # counterproductive in formulas, notably within the install method
 Style/GuardClause:
-  Enabled: false
+  Exclude:
+    - 'Taps/**/*'
 Style/IfUnlessModifier:
+  Exclude:
+    - 'Taps/**/*'
+
+# TODO: enforce when rubocop has fixed this
+# https://github.com/bbatsov/rubocop/issues/3516
+Style/VariableNumber:
+  Enabled: false
+
+# TODO: enforce when rubocop has shipped this
+# https://github.com/bbatsov/rubocop/pull/3513
+Style/TernaryParentheses:
   Enabled: false
 
 # dashes in filenames are typical
-# TODO: enforce when rubocop has fixed this
-# https://github.com/bbatsov/rubocop/issues/1545
 Style/FileName:
-  Enabled: false
+  # matches:
+  #   file_name.rb (default)
+  #   file-name.rb, --filename.rb (command names)
+  #   FILENAME.rb (ARGV and ENV)
+  # does not match:
+  #   dashes-and_underscores.rb
+  Regex: !ruby/regexp /^((([\dA-Z]+|[\da-z]+)(_([\dA-Z]+|[\da-z]+))*|(\-\-)?([\dA-Z]+|[\da-z]+)(-([\dA-Z]+|[\da-z]+))*))(\.rb)?$/
 
 # no percent word array, being friendly to non-ruby users
 # TODO: enforce when rubocop has fixed this
@@ -134,6 +150,7 @@ Style/MethodName:
 Style/PredicateName:
   Exclude:
     - 'Homebrew/compat/**/*'
+  NameWhitelist: is_32_bit?, is_64_bit?
 
 # `formula do` uses nested method definitions
 Lint/NestedMethodDefinition:
diff --git a/Library/.rubocop_todo.yml b/Library/.rubocop_todo.yml
index a898d2f799..80fa07aabe 100644
--- a/Library/.rubocop_todo.yml
+++ b/Library/.rubocop_todo.yml
@@ -1,21 +1,11 @@
 # This configuration was generated by
-# `rubocop --auto-gen-config --exclude-limit 30`
-# on 2016-09-18 15:15:22 +0100 using RuboCop version 0.41.2.
+# `rubocop --auto-gen-config --exclude-limit 100`
+# on 2016-09-22 20:07:41 +0200 using RuboCop version 0.43.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 4
-# Cop supports --auto-correct.
-# Configuration parameters: AlignWith, SupportedStyles, AutoCorrect.
-# SupportedStyles: keyword, variable, start_of_line
-Lint/EndAlignment:
-  Exclude:
-    - 'Homebrew/download_strategy.rb'
-    - 'Homebrew/keg.rb'
-    - 'Homebrew/os/mac/cctools_mach.rb'
-
 # Offense count: 18
 Lint/HandleExceptions:
   Exclude:
@@ -52,11 +42,6 @@ Lint/NestedMethodDefinition:
     - 'Homebrew/dev-cmd/bottle.rb'
     - 'Homebrew/dev-cmd/test-bot.rb'
 
-# Offense count: 2
-Lint/NonLocalExitFromIterator:
-  Exclude:
-    - 'Homebrew/extend/pathname.rb'
-
 # Offense count: 28
 Lint/RescueException:
   Exclude:
@@ -80,12 +65,7 @@ Lint/RescueException:
 # Offense count: 1
 Lint/ShadowedException:
   Exclude:
-    - 'Homebrew/brew.rb'
-
-# Offense count: 2
-Lint/UselessAssignment:
-  Exclude:
-    - 'Homebrew/requirements.rb'
+    - 'Homebrew/utils/fork.rb'
 
 # Offense count: 18
 Metrics/BlockNesting:
@@ -94,19 +74,13 @@ Metrics/BlockNesting:
 # Offense count: 20
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
-  Max: 400
+  Max: 370
 
-# Offense count: 1
+# Offense count: 2
 # Configuration parameters: CountKeywordArgs.
 Metrics/ParameterLists:
   Max: 6
 
-# Offense count: 2
-Performance/FixedSize:
-  Exclude:
-    - 'Homebrew/dev-cmd/audit.rb'
-    - 'Homebrew/dev-cmd/bottle.rb'
-
 # Offense count: 8
 Style/AccessorMethodName:
   Exclude:
@@ -125,33 +99,10 @@ Style/Alias:
   Exclude:
     - 'Homebrew/blacklist.rb'
 
-# Offense count: 26
+# Offense count: 1
 Style/CaseEquality:
   Exclude:
-    - 'Homebrew/cleanup.rb'
-    - 'Homebrew/cmd/search.rb'
     - 'Homebrew/compilers.rb'
-    - 'Homebrew/cxxstdlib.rb'
-    - 'Homebrew/debrew.rb'
-    - 'Homebrew/dependencies.rb'
-    - 'Homebrew/dependency_collector.rb'
-    - 'Homebrew/download_strategy.rb'
-    - 'Homebrew/formula.rb'
-    - 'Homebrew/options.rb'
-    - 'Homebrew/patch.rb'
-    - 'Homebrew/pkg_version.rb'
-    - 'Homebrew/requirement.rb'
-    - 'Homebrew/requirements.rb'
-    - 'Homebrew/software_spec.rb'
-    - 'Homebrew/version.rb'
-
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: IndentWhenRelativeTo, SupportedStyles, IndentOneStep, IndentationWidth.
-# SupportedStyles: case, end
-Style/CaseIndentation:
-  Exclude:
-    - 'Homebrew/keg.rb'
 
 # Offense count: 11
 Style/ClassVars:
@@ -168,17 +119,6 @@ Style/ConstantName:
   Exclude:
     - 'Homebrew/os/mac.rb'
 
-# Offense count: 10
-Style/DoubleNegation:
-  Exclude:
-    - 'Homebrew/extend/ARGV.rb'
-    - 'Homebrew/formula_installer.rb'
-    - 'Homebrew/os/mac/cctools_keg.rb'
-    - 'Homebrew/os/mac/ruby_keg.rb'
-    - 'Homebrew/os/mac/xcode.rb'
-    - 'Homebrew/requirement.rb'
-    - 'Homebrew/software_spec.rb'
-
 # Offense count: 1
 # Configuration parameters: EnforcedStyle, SupportedStyles.
 # SupportedStyles: format, sprintf, percent
@@ -193,22 +133,57 @@ Style/GlobalVars:
     - 'Homebrew/diagnostic.rb'
     - 'Homebrew/utils.rb'
 
-# Offense count: 2
-Style/IdenticalConditionalBranches:
+# Offense count: 70
+# Configuration parameters: MinBodyLength.
+Style/GuardClause:
   Exclude:
-    - 'Homebrew/formula_lock.rb'
-
-# Offense count: 5
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-# SupportedStyles: snake_case, camelCase
-Style/MethodName:
-  Exclude:
-    - 'Homebrew/compat/**/*'
-    - 'Homebrew/cleanup.rb'
-    - 'Homebrew/diagnostic.rb'
-    - 'Homebrew/formula_cellar_checks.rb'
+    - 'Taps/**/*'
+    - 'Homebrew/cmd/update-report.rb'
+    - 'Homebrew/dependency_collector.rb'
+    - 'Homebrew/dev-cmd/audit.rb'
+    - 'Homebrew/dev-cmd/pull.rb'
+    - 'Homebrew/dev-cmd/test-bot.rb'
+    - 'Homebrew/download_strategy.rb'
+    - 'Homebrew/extend/ARGV.rb'
+    - 'Homebrew/extend/ENV/shared.rb'
+    - 'Homebrew/extend/ENV/std.rb'
+    - 'Homebrew/extend/ENV/super.rb'
+    - 'Homebrew/extend/fileutils.rb'
+    - 'Homebrew/extend/os/mac/extend/ENV/std.rb'
+    - 'Homebrew/extend/os/mac/formula_cellar_checks.rb'
+    - 'Homebrew/extend/os/mac/utils/bottles.rb'
+    - 'Homebrew/extend/string.rb'
+    - 'Homebrew/formula.rb'
     - 'Homebrew/formula_installer.rb'
-    - 'Homebrew/os/mac/cctools_mach.rb'
+    - 'Homebrew/formula_lock.rb'
+    - 'Homebrew/formulary.rb'
+    - 'Homebrew/keg.rb'
+    - 'Homebrew/migrator.rb'
+    - 'Homebrew/os/mac/xcode.rb'
+    - 'Homebrew/patch.rb'
+    - 'Homebrew/requirement.rb'
+    - 'Homebrew/tap.rb'
+    - 'Homebrew/test/test_cmd_testbot.rb'
+    - 'Homebrew/test/test_integration_cmds.rb'
+    - 'Homebrew/test/testing_env.rb'
+    - 'Homebrew/utils.rb'
+    - 'Homebrew/utils/popen.rb'
+    - 'Homebrew/version.rb'
+
+# Offense count: 51
+# Cop supports --auto-correct.
+# Configuration parameters: MaxLineLength.
+Style/IfUnlessModifier:
+  Exclude:
+    - 'Taps/**/*'
+    - 'Homebrew/dev-cmd/audit.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: SupportedStyles, IndentationWidth.
+# SupportedStyles: special_inside_parentheses, consistent, align_brackets
+Style/IndentArray:
+  EnforcedStyle: special_inside_parentheses
 
 # Offense count: 7
 # Configuration parameters: EnforcedStyle, SupportedStyles.
@@ -241,14 +216,6 @@ Style/MutableConstant:
     - 'Homebrew/tab.rb'
     - 'Homebrew/tap.rb'
 
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, MinBodyLength, SupportedStyles.
-# SupportedStyles: skip_modifier_ifs, always
-Style/Next:
-  Exclude:
-    - 'Homebrew/dev-cmd/test-bot.rb'
-
 # Offense count: 9
 Style/OpMethod:
   Exclude:
@@ -257,37 +224,9 @@ Style/OpMethod:
     - 'Homebrew/install_renamed.rb'
     - 'Homebrew/options.rb'
 
-# Offense count: 4
-# Configuration parameters: NamePrefix, NamePrefixBlacklist, NameWhitelist.
-# NamePrefix: is_, has_, have_
-# NamePrefixBlacklist: is_, has_, have_
-# NameWhitelist: is_a?
-Style/PredicateName:
-  Exclude:
-    - 'Homebrew/compat/**/*'
-    - 'Homebrew/download_strategy.rb'
-    - 'Homebrew/hardware.rb'
-
-# Offense count: 7
+# Offense count: 2
 # Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, SupportedStyles, AllowInnerSlashes.
-# SupportedStyles: slashes, percent_r, mixed
-Style/RegexpLiteral:
-  Exclude:
-    - 'Homebrew/diagnostic.rb'
-    - 'Homebrew/keg.rb'
-    - 'Homebrew/version.rb'
-
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: AllowAsExpressionSeparator.
-Style/Semicolon:
-  Exclude:
-    - 'Homebrew/descriptions.rb'
-
-# Offense count: 1
-# Configuration parameters: Methods.
-# Methods: {"reduce"=>["a", "e"]}, {"inject"=>["a", "e"]}
-Style/SingleLineBlockParams:
-  Exclude:
-    - 'Homebrew/diagnostic.rb'
+# Configuration parameters: SupportedStyles.
+# SupportedStyles: use_perl_names, use_english_names
+Style/SpecialGlobalVars:
+  EnforcedStyle: use_perl_names
diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index 0d1bcbddab..1ba3fb8c26 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -37,9 +37,9 @@ begin
   cmd = nil
 
   ARGV.dup.each_with_index do |arg, i|
-    if help_flag && cmd
-      break
-    elsif help_flag_list.include?(arg)
+    break if help_flag && cmd
+
+    if help_flag_list.include?(arg)
       # Option-style help: Both `--help <cmd>` and `<cmd> --help` are fine.
       help_flag = true
     elsif arg == "help" && !cmd
diff --git a/Library/Homebrew/build.rb b/Library/Homebrew/build.rb
index f4dde895a7..d3c2833d40 100644
--- a/Library/Homebrew/build.rb
+++ b/Library/Homebrew/build.rb
@@ -31,9 +31,8 @@ class Build
   def post_superenv_hacks
     # Only allow Homebrew-approved directories into the PATH, unless
     # a formula opts-in to allowing the user's path.
-    if formula.env.userpaths? || reqs.any? { |rq| rq.env.userpaths? }
-      ENV.userpaths!
-    end
+    return unless formula.env.userpaths? || reqs.any? { |rq| rq.env.userpaths? }
+    ENV.userpaths!
   end
 
   def effective_build_options_for(dependent)
diff --git a/Library/Homebrew/cask/.rubocop.yml b/Library/Homebrew/cask/.rubocop.yml
index 31a2a193de..076b87f61f 100644
--- a/Library/Homebrew/cask/.rubocop.yml
+++ b/Library/Homebrew/cask/.rubocop.yml
@@ -1,10 +1,8 @@
-require: 'rubocop-cask'
-
 AllCops:
   TargetRubyVersion: 2.0
   Exclude:
+    - '**/.simplecov'
     - '**/Casks/**/*'
-    - 'developer/**/*'
     - '**/vendor/**/*'
 
 Metrics/AbcSize:
@@ -16,10 +14,10 @@ Metrics/ClassLength:
 Metrics/CyclomaticComplexity:
   Enabled: false
 
-Metrics/MethodLength:
+Metrics/LineLength:
   Enabled: false
 
-Metrics/PerceivedComplexity:
+Metrics/MethodLength:
   Enabled: false
 
 Metrics/ModuleLength:
@@ -29,6 +27,16 @@ Metrics/ModuleLength:
     - 'lib/hbc/macos.rb'
     - 'lib/hbc/utils.rb'
 
+Metrics/PerceivedComplexity:
+  Enabled: false
+
+Style/AlignHash:
+  EnforcedHashRocketStyle: table
+  EnforcedColonStyle: table
+
+Style/BarePercentLiterals:
+  EnforcedStyle: percent_q
+
 Style/BlockDelimiters:
   EnforcedStyle: semantic
   FunctionalMethods:
@@ -59,6 +67,8 @@ Style/BlockDelimiters:
     - chdir
     - context
     - create
+    - define_method
+    - define_singleton_method
     - each_with_object
     - fork
     - measure
@@ -75,15 +85,47 @@ Style/BlockDelimiters:
     - lambda
     - proc
 
-
 Style/ClassAndModuleChildren:
   EnforcedStyle: compact
 
-Style/PredicateName:
-  NameWhitelist: is_32_bit?, is_64_bit?
+Style/Documentation:
+  Enabled: false
+
+Style/FileName:
+  Regex: !ruby/regexp /^((([\dA-Z]+|[\da-z]+)(_([\dA-Z]+|[\da-z]+))*|(\-\-)?([\dA-Z]+|[\da-z]+)(-([\dA-Z]+|[\da-z]+))*))(\.rb)?$/
+
+Style/HashSyntax:
+  EnforcedStyle: ruby19_no_mixed_keys
+
+Style/IndentArray:
+  EnforcedStyle: align_brackets
+
+Style/IndentHash:
+  EnforcedStyle: align_braces
+
+Style/PercentLiteralDelimiters:
+  PreferredDelimiters:
+    '%':  '{}'
+    '%i': '{}'
+    '%q': '{}'
+    '%Q': '{}'
+    '%r': '{}'
+    '%s': '()'
+    '%w': '[]'
+    '%W': '[]'
+    '%x': '()'
 
 Style/RaiseArgs:
   EnforcedStyle: exploded
 
+Style/RegexpLiteral:
+  EnforcedStyle: percent_r
+
 Style/StringLiterals:
   EnforcedStyle: double_quotes
+
+Style/StringLiteralsInInterpolation:
+  EnforcedStyle: double_quotes
+
+Style/TrailingCommaInLiteral:
+  EnforcedStyleForMultiline: comma
diff --git a/Library/Homebrew/cask/Gemfile b/Library/Homebrew/cask/Gemfile
index cba638dc9b..df06bd5d4a 100644
--- a/Library/Homebrew/cask/Gemfile
+++ b/Library/Homebrew/cask/Gemfile
@@ -7,10 +7,6 @@ group :debug do
   gem "pry-byebug", platforms: :mri
 end
 
-group :development do
-  gem "rubocop-cask", "~> 0.8.3"
-end
-
 group :test do
   # This is SimpleCov v0.12.0 with two fixes merged on top, that finally resolve
   # all issues with parallel tests, uncovered files, and tracked files. Switch
diff --git a/Library/Homebrew/cask/Gemfile.lock b/Library/Homebrew/cask/Gemfile.lock
index 9d53aebf8a..93dd597127 100644
--- a/Library/Homebrew/cask/Gemfile.lock
+++ b/Library/Homebrew/cask/Gemfile.lock
@@ -12,7 +12,6 @@ GEM
   remote: https://rubygems.org/
   specs:
     ansi (1.5.0)
-    ast (2.3.0)
     builder (3.2.2)
     byebug (9.0.5)
     codecov (0.1.5)
@@ -36,9 +35,6 @@ GEM
     parallel (1.9.0)
     parallel_tests (2.9.0)
       parallel
-    parser (2.3.1.2)
-      ast (~> 2.2)
-    powerpack (0.1.1)
     pry (0.10.4)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
@@ -46,8 +42,6 @@ GEM
     pry-byebug (3.4.0)
       byebug (~> 9.0)
       pry (~> 0.10)
-    public_suffix (2.0.2)
-    rainbow (2.1.0)
     rake (10.4.2)
     rspec (3.0.0)
       rspec-core (~> 3.0.0)
@@ -66,19 +60,9 @@ GEM
     rspec-support (3.0.4)
     rspec-wait (0.0.9)
       rspec (>= 3, < 4)
-    rubocop (0.41.2)
-      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)
-    rubocop-cask (0.8.3)
-      public_suffix (~> 2.0)
-      rubocop (~> 0.41.1)
     ruby-progressbar (1.8.1)
     simplecov-html (0.10.0)
     slop (3.6.0)
-    unicode-display_width (1.1.0)
     url (0.3.2)
 
 PLATFORMS
@@ -96,7 +80,6 @@ DEPENDENCIES
   rspec (~> 3.0.0)
   rspec-its
   rspec-wait
-  rubocop-cask (~> 0.8.3)
   simplecov (= 0.12.0)!
 
 BUNDLED WITH
diff --git a/Library/Homebrew/cask/Rakefile b/Library/Homebrew/cask/Rakefile
index fe3e75c988..ec6a4a7f64 100644
--- a/Library/Homebrew/cask/Rakefile
+++ b/Library/Homebrew/cask/Rakefile
@@ -1,6 +1,5 @@
 require "rake/testtask"
 require "rspec/core/rake_task"
-require "rubocop/rake_task"
 
 homebrew_repo = `brew --repository`.chomp
 $LOAD_PATH.unshift(File.expand_path("#{homebrew_repo}/Library/Homebrew"))
@@ -18,12 +17,6 @@ namespace :test do
   end
 end
 
-RuboCop::RakeTask.new(:rubocop) do |t|
-  t.options = ["--force-exclusion"]
-end
-
-task default: [:rubocop]
-
 desc "Open a REPL for debugging and experimentation"
 task :console do
   require "pry"
diff --git a/Library/Homebrew/cask/lib/hbc/artifact/abstract_flight_block.rb b/Library/Homebrew/cask/lib/hbc/artifact/abstract_flight_block.rb
index fcf98d7adb..c879fc2be9 100644
--- a/Library/Homebrew/cask/lib/hbc/artifact/abstract_flight_block.rb
+++ b/Library/Homebrew/cask/lib/hbc/artifact/abstract_flight_block.rb
@@ -10,7 +10,7 @@ class Hbc::Artifact::AbstractFlightBlock < Hbc::Artifact::Base
   end
 
   def self.class_for_dsl_key(dsl_key)
-    Object.const_get("Hbc::DSL::#{dsl_key.to_s.split('_').collect(&:capitalize).join}")
+    Object.const_get("Hbc::DSL::#{dsl_key.to_s.split("_").collect(&:capitalize).join}")
   end
 
   def self.me?(cask)
diff --git a/Library/Homebrew/cask/lib/hbc/artifact/moved.rb b/Library/Homebrew/cask/lib/hbc/artifact/moved.rb
index 8565ab8360..8f41e9fd54 100644
--- a/Library/Homebrew/cask/lib/hbc/artifact/moved.rb
+++ b/Library/Homebrew/cask/lib/hbc/artifact/moved.rb
@@ -64,9 +64,9 @@ class Hbc::Artifact::Moved < Hbc::Artifact::Relocated
 
   def delete
     ohai "Removing #{self.class.artifact_english_name}: '#{target}'"
-    if MacOS.undeletable?(target)
-      raise Hbc::CaskError, "Cannot remove undeletable #{self.class.artifact_english_name}"
-    elsif force
+    raise Hbc::CaskError, "Cannot remove undeletable #{self.class.artifact_english_name}" if MacOS.undeletable?(target)
+
+    if force
       Hbc::Utils.gain_permissions_remove(target, command: @command)
     else
       target.rmtree
diff --git a/Library/Homebrew/cask/lib/hbc/cache.rb b/Library/Homebrew/cask/lib/hbc/cache.rb
index 9fc5fe0f3c..7ae5fcc8cd 100644
--- a/Library/Homebrew/cask/lib/hbc/cache.rb
+++ b/Library/Homebrew/cask/lib/hbc/cache.rb
@@ -3,32 +3,32 @@ module Hbc::Cache
 
   def ensure_cache_exists
     return if Hbc.cache.exist?
+
     odebug "Creating Cache at #{Hbc.cache}"
     Hbc.cache.mkpath
   end
 
   def migrate_legacy_cache
-    if Hbc.legacy_cache.exist?
-      ohai "Migrating cached files to #{Hbc.cache}..."
+    return unless Hbc.legacy_cache.exist?
 
-      Hbc.legacy_cache.children.select(&:symlink?).each do |symlink|
-        file = symlink.readlink
+    ohai "Migrating cached files to #{Hbc.cache}..."
+    Hbc.legacy_cache.children.select(&:symlink?).each do |symlink|
+      file = symlink.readlink
 
-        new_name = file.basename
-                       .sub(%r{\-((?:(\d|#{Hbc::DSL::Version::DIVIDER_REGEX})*\-\2*)*[^\-]+)$}x,
-                            '--\1')
+      new_name = file.basename
+                     .sub(%r{\-((?:(\d|#{Hbc::DSL::Version::DIVIDER_REGEX})*\-\2*)*[^\-]+)$}x,
+                          '--\1')
 
-        renamed_file = Hbc.cache.join(new_name)
+      renamed_file = Hbc.cache.join(new_name)
 
-        if file.exist?
-          puts "#{file} -> #{renamed_file}"
-          FileUtils.mv(file, renamed_file)
-        end
-
-        FileUtils.rm(symlink)
+      if file.exist?
+        puts "#{file} -> #{renamed_file}"
+        FileUtils.mv(file, renamed_file)
       end
 
-      FileUtils.remove_entry_secure(Hbc.legacy_cache)
+      FileUtils.rm(symlink)
     end
+
+    FileUtils.remove_entry_secure(Hbc.legacy_cache)
   end
 end
diff --git a/Library/Homebrew/cask/lib/hbc/cask.rb b/Library/Homebrew/cask/lib/hbc/cask.rb
index fd13a6fe73..f19e5b81fc 100644
--- a/Library/Homebrew/cask/lib/hbc/cask.rb
+++ b/Library/Homebrew/cask/lib/hbc/cask.rb
@@ -87,28 +87,29 @@ class Hbc::Cask
   end
 
   def dumpcask
-    if Hbc.respond_to?(:debug) && Hbc.debug
-      odebug "Cask instance dumps in YAML:"
-      odebug "Cask instance toplevel:", to_yaml
-      [
-        :name,
-        :homepage,
-        :url,
-        :appcast,
-        :version,
-        :license,
-        :sha256,
-        :artifacts,
-        :caveats,
-        :depends_on,
-        :conflicts_with,
-        :container,
-        :gpg,
-        :accessibility_access,
-        :auto_updates,
-      ].each do |method|
-        odebug "Cask instance method '#{method}':", send(method).to_yaml
-      end
+    return unless Hbc.respond_to?(:debug)
+    return unless Hbc.debug
+
+    odebug "Cask instance dumps in YAML:"
+    odebug "Cask instance toplevel:", to_yaml
+    [
+      :name,
+      :homepage,
+      :url,
+      :appcast,
+      :version,
+      :license,
+      :sha256,
+      :artifacts,
+      :caveats,
+      :depends_on,
+      :conflicts_with,
+      :container,
+      :gpg,
+      :accessibility_access,
+      :auto_updates,
+    ].each do |method|
+      odebug "Cask instance method '#{method}':", send(method).to_yaml
     end
   end
 end
diff --git a/Library/Homebrew/cask/lib/hbc/caskroom.rb b/Library/Homebrew/cask/lib/hbc/caskroom.rb
index 7dcb35d41b..5d26ac222a 100644
--- a/Library/Homebrew/cask/lib/hbc/caskroom.rb
+++ b/Library/Homebrew/cask/lib/hbc/caskroom.rb
@@ -3,39 +3,39 @@ module Hbc::Caskroom
 
   def migrate_caskroom_from_repo_to_prefix
     repo_caskroom = Hbc.homebrew_repository.join("Caskroom")
-    if !Hbc.caskroom.exist? && repo_caskroom.directory?
-      ohai "Moving Caskroom from HOMEBREW_REPOSITORY to HOMEBREW_PREFIX"
+    return if Hbc.caskroom.exist?
+    return unless repo_caskroom.directory?
 
-      if Hbc.caskroom.parent.writable?
-        FileUtils.mv repo_caskroom, Hbc.caskroom
-      else
-        opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
-        system "/usr/bin/sudo", "--", "/bin/mv", "--", repo_caskroom.to_s, Hbc.caskroom.parent.to_s
-      end
+    ohai "Moving Caskroom from HOMEBREW_REPOSITORY to HOMEBREW_PREFIX"
+
+    if Hbc.caskroom.parent.writable?
+      FileUtils.mv repo_caskroom, Hbc.caskroom
+    else
+      opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
+      system "/usr/bin/sudo", "--", "/bin/mv", "--", repo_caskroom.to_s, Hbc.caskroom.parent.to_s
     end
   end
 
   def ensure_caskroom_exists
-    unless Hbc.caskroom.exist?
-      ohai "Creating Caskroom at #{Hbc.caskroom}"
+    return if Hbc.caskroom.exist?
 
-      if Hbc.caskroom.parent.writable?
-        Hbc.caskroom.mkpath
-      else
-        ohai "We'll set permissions properly so we won't need sudo in the future"
-        toplevel_dir = Hbc.caskroom
-        toplevel_dir = toplevel_dir.parent until toplevel_dir.parent.root?
-        unless toplevel_dir.directory?
-          # If a toplevel dir such as '/opt' must be created, enforce standard permissions.
-          # sudo in system is rude.
-          system "/usr/bin/sudo", "--", "/bin/mkdir", "--",         toplevel_dir
-          system "/usr/bin/sudo", "--", "/bin/chmod", "--", "0775", toplevel_dir
-        end
+    ohai "Creating Caskroom at #{Hbc.caskroom}"
+    if Hbc.caskroom.parent.writable?
+      Hbc.caskroom.mkpath
+    else
+      ohai "We'll set permissions properly so we won't need sudo in the future"
+      toplevel_dir = Hbc.caskroom
+      toplevel_dir = toplevel_dir.parent until toplevel_dir.parent.root?
+      unless toplevel_dir.directory?
+        # If a toplevel dir such as '/opt' must be created, enforce standard permissions.
         # sudo in system is rude.
-        system "/usr/bin/sudo", "--", "/bin/mkdir", "-p", "--", Hbc.caskroom
-        unless Hbc.caskroom.parent == toplevel_dir
-          system "/usr/bin/sudo", "--", "/usr/sbin/chown", "-R", "--", "#{Hbc::Utils.current_user}:staff", Hbc.caskroom.parent.to_s
-        end
+        system "/usr/bin/sudo", "--", "/bin/mkdir", "--",         toplevel_dir
+        system "/usr/bin/sudo", "--", "/bin/chmod", "--", "0775", toplevel_dir
+      end
+      # sudo in system is rude.
+      system "/usr/bin/sudo", "--", "/bin/mkdir", "-p", "--", Hbc.caskroom
+      unless Hbc.caskroom.parent == toplevel_dir
+        system "/usr/bin/sudo", "--", "/usr/sbin/chown", "-R", "--", "#{Hbc::Utils.current_user}:staff", Hbc.caskroom.parent.to_s
       end
     end
   end
diff --git a/Library/Homebrew/cask/lib/hbc/cli.rb b/Library/Homebrew/cask/lib/hbc/cli.rb
index 1378176da7..7b3b886b91 100644
--- a/Library/Homebrew/cask/lib/hbc/cli.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli.rb
@@ -117,11 +117,11 @@ class Hbc::CLI
               rescue NameError
                 nil
               end
+
       if klass.respond_to?(:run)
         # invoke "run" on a Ruby library which follows our coding conventions
-        klass.run(*rest)
-      else
         # other Ruby libraries must do everything via "require"
+        klass.run(*rest)
       end
     elsif Hbc::Utils.which "brewcask-#{command}"
       # arbitrary external executable on PATH, Homebrew-style
diff --git a/Library/Homebrew/cask/lib/hbc/cli/audit.rb b/Library/Homebrew/cask/lib/hbc/cli/audit.rb
index 289547b44c..14f3d82540 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/audit.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/audit.rb
@@ -6,7 +6,7 @@ class Hbc::CLI::Audit < Hbc::CLI::Base
   def self.run(*args)
     failed_casks = new(args, Hbc::Auditor).run
     return if failed_casks.empty?
-    raise Hbc::CaskError, "audit failed for casks: #{failed_casks.join(' ')}"
+    raise Hbc::CaskError, "audit failed for casks: #{failed_casks.join(" ")}"
   end
 
   def initialize(args, auditor)
diff --git a/Library/Homebrew/cask/lib/hbc/cli/cleanup.rb b/Library/Homebrew/cask/lib/hbc/cli/cleanup.rb
index 4115d26fc7..39a90e7028 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/cleanup.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/cleanup.rb
@@ -65,7 +65,7 @@ class Hbc::CLI::Cleanup < Hbc::CLI::Base
 
   def remove_cache_files(*tokens)
     message = "Removing cached downloads"
-    message.concat " for #{tokens.join(', ')}" unless tokens.empty?
+    message.concat " for #{tokens.join(", ")}" unless tokens.empty?
     message.concat " older than #{OUTDATED_DAYS} days old" if outdated_only
     ohai message
 
diff --git a/Library/Homebrew/cask/lib/hbc/cli/doctor.rb b/Library/Homebrew/cask/lib/hbc/cli/doctor.rb
index 2632bcaef1..7cfccd8b90 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/doctor.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/doctor.rb
@@ -54,7 +54,7 @@ class Hbc::CLI::Doctor < Hbc::CLI::Base
       if homebrew_origin !~ %r{\S}
         homebrew_origin = "#{none_string} #{error_string}"
       elsif homebrew_origin !~ %r{(mxcl|Homebrew)/(home)?brew(\.git)?\Z}
-        homebrew_origin.concat " #{error_string 'warning: nonstandard origin'}"
+        homebrew_origin.concat " #{error_string "warning: nonstandard origin"}"
       end
     rescue StandardError
       homebrew_origin = error_string "Not Found - Error running git"
@@ -106,7 +106,7 @@ class Hbc::CLI::Doctor < Hbc::CLI::Base
   end
 
   def self.privileged_uid
-    Process.euid == 0 ? "Yes #{error_string 'warning: not recommended'}" : "No"
+    Process.euid.zero? ? "Yes #{error_string "warning: not recommended"}" : "No"
   rescue StandardError
     notfound_string
   end
@@ -143,7 +143,7 @@ class Hbc::CLI::Doctor < Hbc::CLI::Base
       if dir.nil? || dir.to_s.empty?
         none_string
       elsif dir.to_s.match(legacy_tap_pattern)
-        dir.to_s.concat(" #{error_string 'Warning: legacy tap path'}")
+        dir.to_s.concat(" #{error_string "Warning: legacy tap path"}")
       else
         dir.to_s
       end
@@ -175,9 +175,9 @@ class Hbc::CLI::Doctor < Hbc::CLI::Base
   def self.render_staging_location(path)
     path = Pathname.new(path)
     if !path.exist?
-      "#{path} #{error_string 'error: path does not exist'}}"
+      "#{path} #{error_string "error: path does not exist"}}"
     elsif !path.writable?
-      "#{path} #{error_string 'error: not writable by current user'}"
+      "#{path} #{error_string "error: not writable by current user"}"
     else
       path
     end
diff --git a/Library/Homebrew/cask/lib/hbc/cli/install.rb b/Library/Homebrew/cask/lib/hbc/cli/install.rb
index 43eab9f3d5..16e3b8121b 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/install.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/install.rb
@@ -36,7 +36,7 @@ class Hbc::CLI::Install < Hbc::CLI::Base
         count += 1
       end
     end
-    count == 0 ? nil : count == cask_tokens.length
+    count.zero? ? nil : count == cask_tokens.length
   end
 
   def self.warn_unavailable_with_suggestion(cask_token, e)
diff --git a/Library/Homebrew/cask/lib/hbc/cli/internal_audit_modified_casks.rb b/Library/Homebrew/cask/lib/hbc/cli/internal_audit_modified_casks.rb
index f05dbe8038..2cee09eeff 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/internal_audit_modified_casks.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/internal_audit_modified_casks.rb
@@ -62,7 +62,7 @@ class Hbc::CLI::InternalAuditModifiedCasks < Hbc::CLI::InternalUseBase
   end
 
   def git_root
-    @git_root ||= git(*%w[rev-parse --show-toplevel])
+    @git_root ||= git("rev-parse", "--show-toplevel")
   end
 
   def modified_cask_files
@@ -83,8 +83,8 @@ class Hbc::CLI::InternalAuditModifiedCasks < Hbc::CLI::InternalUseBase
     @modified_casks = modified_cask_files.map { |f| Hbc.load(f) }
     if @modified_casks.any?
       num_modified = @modified_casks.size
-      ohai "#{num_modified} modified #{pluralize('cask', num_modified)}: " \
-        "#{@modified_casks.join(' ')}"
+      ohai "#{num_modified} modified #{pluralize("cask", num_modified)}: " \
+        "#{@modified_casks.join(" ")}"
     end
     @modified_casks
   end
@@ -122,7 +122,7 @@ class Hbc::CLI::InternalAuditModifiedCasks < Hbc::CLI::InternalUseBase
     num_failed = failed_casks.size
     cask_pluralized = pluralize("cask", num_failed)
     odie "audit failed for #{num_failed} #{cask_pluralized}: " \
-      "#{failed_casks.join(' ')}"
+      "#{failed_casks.join(" ")}"
   end
 
   def pluralize(str, num)
diff --git a/Library/Homebrew/cask/lib/hbc/cli/internal_dump.rb b/Library/Homebrew/cask/lib/hbc/cli/internal_dump.rb
index d1cfe8d632..1bccf610de 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/internal_dump.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/internal_dump.rb
@@ -21,7 +21,7 @@ class Hbc::CLI::InternalDump < Hbc::CLI::InternalUseBase
         opoo "#{cask_token} was not found or would not load: #{e}"
       end
     end
-    count == 0 ? nil : count == cask_tokens.length
+    count.zero? ? nil : count == cask_tokens.length
   end
 
   def self.help
diff --git a/Library/Homebrew/cask/lib/hbc/cli/internal_stanza.rb b/Library/Homebrew/cask/lib/hbc/cli/internal_stanza.rb
index 651a9ae374..0fb99cc72d 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/internal_stanza.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/internal_stanza.rb
@@ -118,7 +118,7 @@ class Hbc::CLI::InternalStanza < Hbc::CLI::InternalUseBase
 
       count += 1
     end
-    count == 0 ? nil : count == cask_tokens.length
+    count.zero? ? nil : count == cask_tokens.length
   end
 
   def self.help
diff --git a/Library/Homebrew/cask/lib/hbc/cli/list.rb b/Library/Homebrew/cask/lib/hbc/cli/list.rb
index 88907a797c..8b9c671051 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/list.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/list.rb
@@ -48,7 +48,7 @@ class Hbc::CLI::List < Hbc::CLI::Base
       end
     end
 
-    count == 0 ? nil : count == cask_tokens.length
+    count.zero? ? nil : count == cask_tokens.length
   end
 
   def self.list_artifacts(cask)
diff --git a/Library/Homebrew/cask/lib/hbc/cli/uninstall.rb b/Library/Homebrew/cask/lib/hbc/cli/uninstall.rb
index ae15414b72..2ce9b7d4da 100644
--- a/Library/Homebrew/cask/lib/hbc/cli/uninstall.rb
+++ b/Library/Homebrew/cask/lib/hbc/cli/uninstall.rb
@@ -28,8 +28,8 @@ class Hbc::CLI::Uninstall < Hbc::CLI::Base
       single = versions.count == 1
 
       puts <<-EOS.undent
-        #{cask_token} #{versions.join(', ')} #{single ? 'is' : 'are'} still installed.
-        Remove #{single ? 'it' : 'them all'} with `brew cask uninstall --force #{cask_token}`.
+        #{cask_token} #{versions.join(", ")} #{single ? "is" : "are"} still installed.
+        Remove #{single ? "it" : "them all"} with `brew cask uninstall --force #{cask_token}`.
       EOS
     end
   end
diff --git a/Library/Homebrew/cask/lib/hbc/dsl.rb b/Library/Homebrew/cask/lib/hbc/dsl.rb
index f390125421..b947741eab 100644
--- a/Library/Homebrew/cask/lib/hbc/dsl.rb
+++ b/Library/Homebrew/cask/lib/hbc/dsl.rb
@@ -269,8 +269,16 @@ class Hbc::DSL
   end
 
   def method_missing(method, *)
-    Hbc::Utils.method_missing_message(method, token)
-    nil
+    if method
+      Hbc::Utils.method_missing_message(method, token)
+      nil
+    else
+      super
+    end
+  end
+
+  def respond_to_missing?(*)
+    true
   end
 
   def appdir
diff --git a/Library/Homebrew/cask/lib/hbc/dsl/base.rb b/Library/Homebrew/cask/lib/hbc/dsl/base.rb
index 4bf62014e6..f47f3aab78 100644
--- a/Library/Homebrew/cask/lib/hbc/dsl/base.rb
+++ b/Library/Homebrew/cask/lib/hbc/dsl/base.rb
@@ -13,9 +13,17 @@ class Hbc::DSL::Base
   end
 
   def method_missing(method, *)
-    underscored_class = self.class.name.gsub(%r{([[:lower:]])([[:upper:]][[:lower:]])}, '\1_\2').downcase
-    section = underscored_class.downcase.split("::").last
-    Hbc::Utils.method_missing_message(method, @cask.to_s, section)
-    nil
+    if method
+      underscored_class = self.class.name.gsub(%r{([[:lower:]])([[:upper:]][[:lower:]])}, '\1_\2').downcase
+      section = underscored_class.downcase.split("::").last
+      Hbc::Utils.method_missing_message(method, @cask.to_s, section)
+      nil
+    else
+      super
+    end
+  end
+
+  def respond_to_missing?(*)
+    true
   end
 end
diff --git a/Library/Homebrew/cask/lib/hbc/dsl/stanza_proxy.rb b/Library/Homebrew/cask/lib/hbc/dsl/stanza_proxy.rb
index 02c76fb278..218178faa2 100644
--- a/Library/Homebrew/cask/lib/hbc/dsl/stanza_proxy.rb
+++ b/Library/Homebrew/cask/lib/hbc/dsl/stanza_proxy.rb
@@ -25,13 +25,21 @@ class Hbc::DSL::StanzaProxy
     coder["resolved"] = @resolver.call
   end
 
-  def respond_to?(symbol, include_private = false)
-    return true if %i{encode_with proxy? to_s type}.include?(symbol)
-    return false if symbol == :to_ary
-    @resolver.call.respond_to?(symbol, include_private)
+  def method_missing(method, *args)
+    if method != :to_ary
+      @resolver.call.send(method, *args)
+    else
+      super
+    end
   end
 
-  def method_missing(symbol, *args)
-    @resolver.call.send(symbol, *args)
+  def respond_to?(method, include_private = false)
+    return true if %i{encode_with proxy? to_s type}.include?(method)
+    return false if method == :to_ary
+    @resolver.call.respond_to?(method, include_private)
+  end
+
+  def respond_to_missing?(*)
+    true
   end
 end
diff --git a/Library/Homebrew/cask/lib/hbc/installer.rb b/Library/Homebrew/cask/lib/hbc/installer.rb
index 72a9b30774..fad79644e1 100644
--- a/Library/Homebrew/cask/lib/hbc/installer.rb
+++ b/Library/Homebrew/cask/lib/hbc/installer.rb
@@ -139,15 +139,15 @@ class Hbc::Installer
   #       dependencies should also apply for "brew cask stage"
   #       override dependencies with --force or perhaps --force-deps
   def satisfy_dependencies
-    if @cask.depends_on
-      ohai "Satisfying dependencies"
-      macos_dependencies
-      arch_dependencies
-      x11_dependencies
-      formula_dependencies
-      cask_dependencies unless skip_cask_deps
-      puts "complete"
-    end
+    return unless @cask.depends_on
+
+    ohai "Satisfying dependencies"
+    macos_dependencies
+    arch_dependencies
+    x11_dependencies
+    formula_dependencies
+    cask_dependencies unless skip_cask_deps
+    puts "complete"
   end
 
   def macos_dependencies
@@ -159,7 +159,7 @@ class Hbc::Installer
       end
     elsif @cask.depends_on.macos.length > 1
       unless @cask.depends_on.macos.include?(Gem::Version.new(MacOS.version.to_s))
-        raise Hbc::CaskError, "Cask #{@cask} depends on macOS release being one of [#{@cask.depends_on.macos.map(&:to_s).join(', ')}], but you are running release #{MacOS.version}."
+        raise Hbc::CaskError, "Cask #{@cask} depends on macOS release being one of [#{@cask.depends_on.macos.map(&:to_s).join(", ")}], but you are running release #{MacOS.version}."
       end
     else
       unless MacOS.version == @cask.depends_on.macos.first
@@ -175,7 +175,7 @@ class Hbc::Installer
       arch[:type] == @current_arch[:type] &&
       Array(arch[:bits]).include?(@current_arch[:bits])
     }
-    raise Hbc::CaskError, "Cask #{@cask} depends on hardware architecture being one of [#{@cask.depends_on.arch.map(&:to_s).join(', ')}], but you are running #{@current_arch}"
+    raise Hbc::CaskError, "Cask #{@cask} depends on hardware architecture being one of [#{@cask.depends_on.arch.map(&:to_s).join(", ")}], but you are running #{@current_arch}"
   end
 
   def x11_dependencies
@@ -203,7 +203,7 @@ class Hbc::Installer
 
   def cask_dependencies
     return unless @cask.depends_on.cask && !@cask.depends_on.cask.empty?
-    ohai "Installing Cask dependencies: #{@cask.depends_on.cask.join(', ')}"
+    ohai "Installing Cask dependencies: #{@cask.depends_on.cask.join(", ")}"
     deps = Hbc::CaskDependencies.new(@cask)
     deps.sorted.each do |dep_token|
       puts "#{dep_token} ..."
diff --git a/Library/Homebrew/cask/lib/hbc/source/tapped_qualified.rb b/Library/Homebrew/cask/lib/hbc/source/tapped_qualified.rb
index 1da013db2d..97a35defeb 100644
--- a/Library/Homebrew/cask/lib/hbc/source/tapped_qualified.rb
+++ b/Library/Homebrew/cask/lib/hbc/source/tapped_qualified.rb
@@ -11,7 +11,7 @@ class Hbc::Source::TappedQualified < Hbc::Source::Tapped
     qualified_token = Hbc::QualifiedToken.parse(query)
     return if qualified_token.nil?
 
-    user, repo, token = qualified_token
+    user, repo = qualified_token[0..1]
     Tap.fetch(user, repo)
   end
 
diff --git a/Library/Homebrew/cask/lib/hbc/system_command.rb b/Library/Homebrew/cask/lib/hbc/system_command.rb
index bb8d91504e..9ffe9da387 100644
--- a/Library/Homebrew/cask/lib/hbc/system_command.rb
+++ b/Library/Homebrew/cask/lib/hbc/system_command.rb
@@ -123,7 +123,7 @@ class Hbc::SystemCommand::Result
   end
 
   def success?
-    @exit_status == 0
+    @exit_status.zero?
   end
 
   def merged_output
diff --git a/Library/Homebrew/cask/lib/hbc/url_checker.rb b/Library/Homebrew/cask/lib/hbc/url_checker.rb
index 8737903df1..327306b2bb 100644
--- a/Library/Homebrew/cask/lib/hbc/url_checker.rb
+++ b/Library/Homebrew/cask/lib/hbc/url_checker.rb
@@ -36,7 +36,7 @@ class Hbc::UrlChecker
   def _check_response_status
     ok = OK_RESPONSES[cask.url.scheme]
     return if ok.include?(@response_status)
-    add_error "unexpected http response, expecting #{ok.map(&:utf8_inspect).join(' or ')}, got #{@response_status.utf8_inspect}"
+    add_error "unexpected http response, expecting #{ok.map(&:utf8_inspect).join(" or ")}, got #{@response_status.utf8_inspect}"
   end
 
   def _get_data_from_request
diff --git a/Library/Homebrew/cask/lib/hbc/utils.rb b/Library/Homebrew/cask/lib/hbc/utils.rb
index 5991275230..1b80f6ae22 100644
--- a/Library/Homebrew/cask/lib/hbc/utils.rb
+++ b/Library/Homebrew/cask/lib/hbc/utils.rb
@@ -32,14 +32,15 @@ end
 # global methods
 
 def odebug(title, *sput)
-  if Hbc.respond_to?(:debug) && Hbc.debug
-    width = Tty.width * 4 - 6
-    if $stdout.tty? && title.to_s.length > width
-      title = title.to_s[0, width - 3] + "..."
-    end
-    puts "#{Tty.magenta}==>#{Tty.reset} #{Tty.white}#{title}#{Tty.reset}"
-    puts sput unless sput.empty?
+  return unless Hbc.respond_to?(:debug)
+  return unless Hbc.debug
+
+  width = Tty.width * 4 - 6
+  if $stdout.tty? && title.to_s.length > width
+    title = title.to_s[0, width - 3] + "..."
   end
+  puts "#{Tty.magenta}==>#{Tty.reset} #{Tty.white}#{title}#{Tty.reset}"
+  puts sput unless sput.empty?
 end
 
 module Hbc::Utils
diff --git a/Library/Homebrew/cask/spec/cask/cli/cleanup_spec.rb b/Library/Homebrew/cask/spec/cask/cli/cleanup_spec.rb
index ab2cd55cc4..fe8bb2d4db 100644
--- a/Library/Homebrew/cask/spec/cask/cli/cleanup_spec.rb
+++ b/Library/Homebrew/cask/spec/cask/cli/cleanup_spec.rb
@@ -12,7 +12,7 @@ describe Hbc::CLI::Cleanup do
 
   describe "cleanup" do
     it "removes cached downloads of given casks" do
-      cleaned_up_cached_download = 'caffeine'
+      cleaned_up_cached_download = "caffeine"
 
       cached_downloads = [
                            cache_location.join("#{cleaned_up_cached_download}--latest.zip"),
diff --git a/Library/Homebrew/cask/spec/spec_helper.rb b/Library/Homebrew/cask/spec/spec_helper.rb
index bfd4407e00..5a26884ac3 100644
--- a/Library/Homebrew/cask/spec/spec_helper.rb
+++ b/Library/Homebrew/cask/spec/spec_helper.rb
@@ -9,7 +9,7 @@ end
 project_root = Pathname.new(File.expand_path("../..", __FILE__))
 
 # add Homebrew to load path
-$LOAD_PATH.unshift(File.expand_path("#{ENV['HOMEBREW_REPOSITORY']}/Library/Homebrew"))
+$LOAD_PATH.unshift(File.expand_path("#{ENV["HOMEBREW_REPOSITORY"]}/Library/Homebrew"))
 
 require "global"
 
diff --git a/Library/Homebrew/cask/test/cask/artifact/two_apps_correct_test.rb b/Library/Homebrew/cask/test/cask/artifact/two_apps_correct_test.rb
index afa4a61aaf..47408ab9f9 100644
--- a/Library/Homebrew/cask/test/cask/artifact/two_apps_correct_test.rb
+++ b/Library/Homebrew/cask/test/cask/artifact/two_apps_correct_test.rb
@@ -60,7 +60,6 @@ describe Hbc::Artifact::App do
       File.exist?(cask.staged_path.join("Caffeine Deluxe.app")).must_equal true
     end
 
-
     describe "avoids clobbering an existing app" do
       let(:cask) { local_two_apps_caffeine }
 
@@ -70,8 +69,8 @@ describe Hbc::Artifact::App do
         TestHelper.must_output(self, lambda {
           Hbc::Artifact::App.new(cask).install_phase
         }, <<-EOS.undent.chomp)
-             ==> It seems there is already an App at '#{Hbc.appdir.join('Caffeine Mini.app')}'; not moving.
-             ==> Moving App 'Caffeine Pro.app' to '#{Hbc.appdir.join('Caffeine Pro.app')}'
+             ==> It seems there is already an App at '#{Hbc.appdir.join("Caffeine Mini.app")}'; not moving.
+             ==> Moving App 'Caffeine Pro.app' to '#{Hbc.appdir.join("Caffeine Pro.app")}'
            EOS
 
         source_path = cask.staged_path.join("Caffeine Mini.app")
@@ -85,8 +84,8 @@ describe Hbc::Artifact::App do
         TestHelper.must_output(self, lambda {
           Hbc::Artifact::App.new(cask).install_phase
         }, <<-EOS.undent.chomp)
-             ==> Moving App 'Caffeine Mini.app' to '#{Hbc.appdir.join('Caffeine Mini.app')}'
-             ==> It seems there is already an App at '#{Hbc.appdir.join('Caffeine Pro.app')}'; not moving.
+             ==> Moving App 'Caffeine Mini.app' to '#{Hbc.appdir.join("Caffeine Mini.app")}'
+             ==> It seems there is already an App at '#{Hbc.appdir.join("Caffeine Pro.app")}'; not moving.
            EOS
 
         source_path = cask.staged_path.join("Caffeine Pro.app")
diff --git a/Library/Homebrew/cask/test/cask/cli/list_test.rb b/Library/Homebrew/cask/test/cask/cli/list_test.rb
index 2189498d41..6831bf0a4f 100644
--- a/Library/Homebrew/cask/test/cask/cli/list_test.rb
+++ b/Library/Homebrew/cask/test/cask/cli/list_test.rb
@@ -79,9 +79,9 @@ describe Hbc::CLI::List do
         Hbc::CLI::List.run("local-transmission", "local-caffeine")
       }.must_output <<-EOS.undent
       ==> Apps
-      #{Hbc.appdir.join('Transmission.app')} (#{Hbc.appdir.join('Transmission.app').abv})
+      #{Hbc.appdir.join("Transmission.app")} (#{Hbc.appdir.join("Transmission.app").abv})
       ==> Apps
-      Missing App: #{Hbc.appdir.join('Caffeine.app')}
+      Missing App: #{Hbc.appdir.join("Caffeine.app")}
     EOS
     end
   end
diff --git a/Library/Homebrew/cask/test/test_helper.rb b/Library/Homebrew/cask/test/test_helper.rb
index 3599b43bed..4d795bffe9 100644
--- a/Library/Homebrew/cask/test/test_helper.rb
+++ b/Library/Homebrew/cask/test/test_helper.rb
@@ -10,7 +10,7 @@ project_root = Pathname.new(File.expand_path("../..", __FILE__))
 tap_root = Pathname.new(ENV["HOMEBREW_LIBRARY"]).join("Taps", "caskroom", "homebrew-cask")
 
 # add Homebrew to load path
-$LOAD_PATH.unshift(File.expand_path("#{ENV['HOMEBREW_REPOSITORY']}/Library/Homebrew"))
+$LOAD_PATH.unshift(File.expand_path("#{ENV["HOMEBREW_REPOSITORY"]}/Library/Homebrew"))
 
 require "global"
 
diff --git a/Library/Homebrew/caveats.rb b/Library/Homebrew/caveats.rb
index 9c1787f87a..a5568cb29a 100644
--- a/Library/Homebrew/caveats.rb
+++ b/Library/Homebrew/caveats.rb
@@ -69,27 +69,34 @@ class Caveats
   end
 
   def bash_completion_caveats
-    if keg && keg.completion_installed?(:bash) then <<-EOS.undent
+    return unless keg
+    return unless keg.completion_installed?(:bash)
+
+    <<-EOS.undent
       Bash completion has been installed to:
         #{HOMEBREW_PREFIX}/etc/bash_completion.d
-      EOS
-    end
+    EOS
   end
 
   def zsh_completion_caveats
-    if keg && keg.completion_installed?(:zsh) then <<-EOS.undent
+    return unless keg
+    return unless keg.completion_installed?(:zsh)
+
+    <<-EOS.undent
       zsh completion has been installed to:
         #{HOMEBREW_PREFIX}/share/zsh/site-functions
-      EOS
-    end
+    EOS
   end
 
   def fish_completion_caveats
-    if keg && keg.completion_installed?(:fish) && which("fish") then <<-EOS.undent
+    return unless keg
+    return unless keg.completion_installed?(:fish)
+    return unless which("fish")
+
+    <<-EOS.undent
       fish completion has been installed to:
         #{HOMEBREW_PREFIX}/share/fish/vendor_completions.d
-      EOS
-    end
+    EOS
   end
 
   def python_caveats
@@ -140,22 +147,24 @@ class Caveats
   end
 
   def app_caveats
-    if keg && keg.app_installed?
-      <<-EOS.undent
-        .app bundles were installed.
-        Run `brew linkapps #{keg.name}` to symlink these to /Applications.
-      EOS
-    end
+    return unless keg
+    return unless keg.app_installed?
+
+    <<-EOS.undent
+      .app bundles were installed.
+      Run `brew linkapps #{keg.name}` to symlink these to /Applications.
+    EOS
   end
 
   def elisp_caveats
     return if f.keg_only?
-    if keg && keg.elisp_installed?
-      <<-EOS.undent
-        Emacs Lisp files have been installed to:
-          #{HOMEBREW_PREFIX}/share/emacs/site-lisp/#{f.name}
-      EOS
-    end
+    return unless keg
+    return unless keg.elisp_installed?
+
+    <<-EOS.undent
+      Emacs Lisp files have been installed to:
+        #{HOMEBREW_PREFIX}/share/emacs/site-lisp/#{f.name}
+    EOS
   end
 
   def plist_caveats
diff --git a/Library/Homebrew/cleaner.rb b/Library/Homebrew/cleaner.rb
index d8a9985766..7456e18d65 100644
--- a/Library/Homebrew/cleaner.rb
+++ b/Library/Homebrew/cleaner.rb
@@ -87,9 +87,9 @@ class Cleaner
 
       Find.prune if @f.skip_clean? path
 
-      if path.symlink? || path.directory?
-        next
-      elsif path.extname == ".la"
+      next if path.symlink? || path.directory?
+
+      if path.extname == ".la"
         path.unlink
       elsif path.basename.to_s == "perllocal.pod"
         # Both this file & the .packlist one below are completely unnecessary
diff --git a/Library/Homebrew/cleanup.rb b/Library/Homebrew/cleanup.rb
index 265f06d26a..04a976e553 100644
--- a/Library/Homebrew/cleanup.rb
+++ b/Library/Homebrew/cleanup.rb
@@ -12,7 +12,7 @@ module Homebrew
       cleanup_logs
       unless ARGV.dry_run?
         cleanup_lockfiles
-        rm_DS_Store
+        rm_ds_store
       end
     end
 
@@ -66,7 +66,7 @@ module Homebrew
         next unless path.file?
         file = path
 
-        if Pathname::BOTTLE_EXTNAME_RX === file.to_s
+        if file.to_s =~ Pathname::BOTTLE_EXTNAME_RX
           version = begin
                       Utils::Bottles.resolve_version(file)
                     rescue
@@ -86,7 +86,7 @@ module Homebrew
           next
         end
 
-        file_is_stale = if PkgVersion === version
+        file_is_stale = if version.is_a?(PkgVersion)
           f.pkg_version > version
         else
           f.version > version
@@ -119,7 +119,7 @@ module Homebrew
       end
     end
 
-    def self.rm_DS_Store
+    def self.rm_ds_store
       paths = Queue.new
       %w[Cellar Frameworks Library bin etc include lib opt sbin share var]
         .map { |p| HOMEBREW_PREFIX/p }.each { |p| paths << p if p.exist? }
diff --git a/Library/Homebrew/cmd/cleanup.rb b/Library/Homebrew/cmd/cleanup.rb
index a9d3fbcde5..6e0915c9a8 100644
--- a/Library/Homebrew/cmd/cleanup.rb
+++ b/Library/Homebrew/cmd/cleanup.rb
@@ -22,13 +22,13 @@ module Homebrew
       ARGV.resolved_formulae.each { |f| Cleanup.cleanup_formula f }
     end
 
-    if Cleanup.disk_cleanup_size > 0
-      disk_space = disk_usage_readable(Cleanup.disk_cleanup_size)
-      if ARGV.dry_run?
-        ohai "This operation would free approximately #{disk_space} of disk space."
-      else
-        ohai "This operation has freed approximately #{disk_space} of disk space."
-      end
+    return if Cleanup.disk_cleanup_size.zero?
+
+    disk_space = disk_usage_readable(Cleanup.disk_cleanup_size)
+    if ARGV.dry_run?
+      ohai "This operation would free approximately #{disk_space} of disk space."
+    else
+      ohai "This operation has freed approximately #{disk_space} of disk space."
     end
   end
 end
diff --git a/Library/Homebrew/cmd/diy.rb b/Library/Homebrew/cmd/diy.rb
index 8262352f82..95ec7fe35b 100644
--- a/Library/Homebrew/cmd/diy.rb
+++ b/Library/Homebrew/cmd/diy.rb
@@ -31,11 +31,9 @@ module Homebrew
   def detect_version(path)
     version = path.version.to_s
 
-    if version.empty?
-      raise "Couldn't determine version, set it with --version=<version>"
-    else
-      version
-    end
+    raise "Couldn't determine version, set it with --version=<version>" if version.empty?
+
+    version
   end
 
   def detect_name(path, version)
diff --git a/Library/Homebrew/cmd/info.rb b/Library/Homebrew/cmd/info.rb
index 2474aad573..09c832203c 100644
--- a/Library/Homebrew/cmd/info.rb
+++ b/Library/Homebrew/cmd/info.rb
@@ -54,11 +54,8 @@ module Homebrew
           end
         rescue FormulaUnavailableError
           # No formula with this name, try a blacklist lookup
-          if (blacklist = blacklisted?(f))
-            puts blacklist
-          else
-            raise
-          end
+          raise unless (blacklist = blacklisted?(f))
+          puts blacklist
         end
       end
     end
diff --git a/Library/Homebrew/cmd/install.rb b/Library/Homebrew/cmd/install.rb
index 50439ccf9d..0a6dd5a469 100644
--- a/Library/Homebrew/cmd/install.rb
+++ b/Library/Homebrew/cmd/install.rb
@@ -245,11 +245,11 @@ module Homebrew
   end
 
   def check_macports
-    unless MacOS.macports_or_fink.empty?
-      opoo "It appears you have MacPorts or Fink installed."
-      puts "Software installed with other package managers causes known problems for"
-      puts "Homebrew. If a formula fails to build, uninstall MacPorts/Fink and try again."
-    end
+    return if MacOS.macports_or_fink.empty?
+
+    opoo "It appears you have MacPorts or Fink installed."
+    puts "Software installed with other package managers causes known problems for"
+    puts "Homebrew. If a formula fails to build, uninstall MacPorts/Fink and try again."
   end
 
   def check_cellar
diff --git a/Library/Homebrew/cmd/reinstall.rb b/Library/Homebrew/cmd/reinstall.rb
index e51aace2ad..bda6022bfd 100644
--- a/Library/Homebrew/cmd/reinstall.rb
+++ b/Library/Homebrew/cmd/reinstall.rb
@@ -58,10 +58,11 @@ module Homebrew
 
   def restore_backup(keg, formula)
     path = backup_path(keg)
-    if path.directory?
-      path.rename keg
-      keg.link unless formula.keg_only?
-    end
+
+    return unless path.directory?
+
+    path.rename keg
+    keg.link unless formula.keg_only?
   end
 
   def backup_path(path)
diff --git a/Library/Homebrew/cmd/search.rb b/Library/Homebrew/cmd/search.rb
index 50d9f5f744..aa80ec5895 100644
--- a/Library/Homebrew/cmd/search.rb
+++ b/Library/Homebrew/cmd/search.rb
@@ -150,7 +150,7 @@ module Homebrew
 
     names = remote_tap_formulae["#{user}/#{repo}"]
     user = user.downcase if user == "Homebrew" # special handling for the Homebrew organization
-    names.select { |name| rx === name }.map { |name| "#{user}/#{repo}/#{name}" }
+    names.select { |name| name =~ rx }.map { |name| "#{user}/#{repo}/#{name}" }
   rescue GitHub::HTTPNotFoundError
     opoo "Failed to search tap: #{user}/#{repo}. Please run `brew update`"
     []
@@ -171,10 +171,11 @@ module Homebrew
       rescue
         canonical_name = canonical_full_name = name
       end
+
       # Ignore aliases from results when the full name was also found
-      if aliases.include?(name) && results.include?(canonical_full_name)
-        next
-      elsif (HOMEBREW_CELLAR/canonical_name).directory?
+      next if aliases.include?(name) && results.include?(canonical_full_name)
+
+      if (HOMEBREW_CELLAR/canonical_name).directory?
         pretty_installed(name)
       else
         name
diff --git a/Library/Homebrew/cmd/style.rb b/Library/Homebrew/cmd/style.rb
index f28d50cc1e..db61116be7 100644
--- a/Library/Homebrew/cmd/style.rb
+++ b/Library/Homebrew/cmd/style.rb
@@ -45,7 +45,7 @@ module Homebrew
 
   def check_style_impl(files, output_type, options = {})
     fix = options[:fix]
-    Homebrew.install_gem_setup_path! "rubocop", "0.41.2"
+    Homebrew.install_gem_setup_path! "rubocop", "0.43.0"
 
     args = %W[
       --force-exclusion
@@ -54,20 +54,22 @@ module Homebrew
     args << "--auto-correct" if fix
     args += files
 
-    case output_type
-    when :print
-      args << "--display-cop-names" if ARGV.include? "--display-cop-names"
-      system "rubocop", "--format", "simple", *args
-      !$?.success?
-    when :json
-      json = Utils.popen_read_text("rubocop", "--format", "json", *args)
-      # exit status of 1 just means violations were found; other numbers mean execution errors
-      # exitstatus can also be nil if RuboCop process crashes, e.g. due to
-      # native extension problems
-      raise "Error while running RuboCop" if $?.exitstatus.nil? || $?.exitstatus > 1
-      RubocopResults.new(Utils::JSON.load(json))
-    else
-      raise "Invalid output_type for check_style_impl: #{output_type}"
+    HOMEBREW_LIBRARY.cd do
+      case output_type
+      when :print
+        args << "--display-cop-names" if ARGV.include? "--display-cop-names"
+        system "rubocop", "--format", "simple", *args
+        !$?.success?
+      when :json
+        json = Utils.popen_read_text("rubocop", "--format", "json", *args)
+        # exit status of 1 just means violations were found; other numbers mean execution errors
+        # exitstatus can also be nil if RuboCop process crashes, e.g. due to
+        # native extension problems
+        raise "Error while running RuboCop" if $?.exitstatus.nil? || $?.exitstatus > 1
+        RubocopResults.new(Utils::JSON.load(json))
+      else
+        raise "Invalid output_type for check_style_impl: #{output_type}"
+      end
     end
   end
 
diff --git a/Library/Homebrew/cxxstdlib.rb b/Library/Homebrew/cxxstdlib.rb
index 1f629a8b28..ad859badd3 100644
--- a/Library/Homebrew/cxxstdlib.rb
+++ b/Library/Homebrew/cxxstdlib.rb
@@ -16,7 +16,7 @@ class CxxStdlib
     if type && ![:libstdcxx, :libcxx].include?(type)
       raise ArgumentError, "Invalid C++ stdlib type: #{type}"
     end
-    klass = GNU_GCC_REGEXP === compiler.to_s ? GnuStdlib : AppleStdlib
+    klass = compiler.to_s =~ GNU_GCC_REGEXP ? GnuStdlib : AppleStdlib
     klass.new(type, compiler)
   end
 
diff --git a/Library/Homebrew/debrew.rb b/Library/Homebrew/debrew.rb
index 48d449f4a2..8e371e4e79 100644
--- a/Library/Homebrew/debrew.rb
+++ b/Library/Homebrew/debrew.rb
@@ -118,20 +118,22 @@ module Debrew
           menu.prompt = "Choose an action: "
 
           menu.choice(:raise) { original_raise(e) }
-          menu.choice(:ignore) { return :ignore } if Ignorable === e
+          menu.choice(:ignore) { return :ignore } if e.is_a?(Ignorable)
           menu.choice(:backtrace) { puts e.backtrace }
 
-          menu.choice(:irb) do
-            puts "When you exit this IRB session, execution will continue."
-            set_trace_func proc { |event, _, _, id, binding, klass|
-              if klass == Raise && id == :raise && event == "return"
-                set_trace_func(nil)
-                synchronize { IRB.start_within(binding) }
-              end
-            }
+          if e.is_a?(Ignorable)
+            menu.choice(:irb) do
+              puts "When you exit this IRB session, execution will continue."
+              set_trace_func proc { |event, _, _, id, binding, klass|
+                if klass == Raise && id == :raise && event == "return"
+                  set_trace_func(nil)
+                  synchronize { IRB.start_within(binding) }
+                end
+              }
 
-            return :ignore
-          end if Ignorable === e
+              return :ignore
+            end
+          end
 
           menu.choice(:shell) do
             puts "When you exit this shell, you will return to the menu."
diff --git a/Library/Homebrew/dependencies.rb b/Library/Homebrew/dependencies.rb
index b55d35c2eb..51e5521029 100644
--- a/Library/Homebrew/dependencies.rb
+++ b/Library/Homebrew/dependencies.rb
@@ -69,7 +69,7 @@ class Requirements
   end
 
   def <<(other)
-    if Comparable === other
+    if other.is_a?(Comparable)
       @reqs.grep(other.class) do |req|
         return self if req > other
         @reqs.delete(req)
diff --git a/Library/Homebrew/dependency_collector.rb b/Library/Homebrew/dependency_collector.rb
index ef3a712e96..0b35e7fb40 100644
--- a/Library/Homebrew/dependency_collector.rb
+++ b/Library/Homebrew/dependency_collector.rb
@@ -49,7 +49,7 @@ class DependencyCollector
   end
 
   def cache_key(spec)
-    if Resource === spec && spec.download_strategy == CurlDownloadStrategy
+    if spec.is_a?(Resource) && spec.download_strategy == CurlDownloadStrategy
       File.extname(spec.url)
     else
       spec
@@ -57,7 +57,7 @@ class DependencyCollector
   end
 
   def build(spec)
-    spec, tags = Hash === spec ? spec.first : spec
+    spec, tags = spec.is_a?(Hash) ? spec.first : spec
     parse_spec(spec, Array(tags))
   end
 
@@ -81,7 +81,7 @@ class DependencyCollector
   end
 
   def parse_string_spec(spec, tags)
-    if HOMEBREW_TAP_FORMULA_REGEX === spec
+    if spec =~ HOMEBREW_TAP_FORMULA_REGEX
       TapDependency.new(spec, tags)
     elsif tags.empty?
       Dependency.new(spec, tags)
@@ -165,11 +165,11 @@ class DependencyCollector
 
   def parse_url_spec(url, tags)
     case File.extname(url)
-    when ".xz"  then Dependency.new("xz", tags)
+    when ".xz"          then Dependency.new("xz", tags)
     when ".lha", ".lzh" then Dependency.new("lha", tags)
-    when ".lz"  then Dependency.new("lzip", tags)
-    when ".rar" then Dependency.new("unrar", tags)
-    when ".7z"  then Dependency.new("p7zip", tags)
+    when ".lz"          then Dependency.new("lzip", tags)
+    when ".rar"         then Dependency.new("unrar", tags)
+    when ".7z"          then Dependency.new("p7zip", tags)
     end
   end
 end
diff --git a/Library/Homebrew/descriptions.rb b/Library/Homebrew/descriptions.rb
index 5e7a5b06c5..0ef4316d34 100644
--- a/Library/Homebrew/descriptions.rb
+++ b/Library/Homebrew/descriptions.rb
@@ -12,9 +12,7 @@ class Descriptions
   # If the cache file exists, load it into, and return, a hash; otherwise,
   # return nil.
   def self.load_cache
-    if CACHE_FILE.exist?
-      @cache = Utils::JSON.load(CACHE_FILE.read)
-    end
+    @cache = Utils::JSON.load(CACHE_FILE.read) if CACHE_FILE.exist?
   end
 
   # Write the cache to disk after ensuring the existence of the containing
@@ -138,6 +136,6 @@ class Descriptions
 
   def short_name_counts
     @short_name_counts ||=
-      short_names.values.each_with_object(Hash.new(0)) { |name, counts| counts[name] += 1; counts }
+      short_names.values.each_with_object(Hash.new(0)) { |name, counts| counts[name] += 1 }
   end
 end
diff --git a/Library/Homebrew/dev-cmd/audit.rb b/Library/Homebrew/dev-cmd/audit.rb
index 20e9a8aff0..61d136dafe 100644
--- a/Library/Homebrew/dev-cmd/audit.rb
+++ b/Library/Homebrew/dev-cmd/audit.rb
@@ -83,11 +83,11 @@ module Homebrew
       end
     end
 
-    unless problem_count.zero?
-      problems = "problem" + plural(problem_count)
-      formulae = "formula" + plural(formula_count, "e")
-      ofail "#{problem_count} #{problems} in #{formula_count} #{formulae}"
-    end
+    return if problem_count.zero?
+
+    problems = "problem" + plural(problem_count)
+    formulae = "formula" + plural(formula_count, "e")
+    ofail "#{problem_count} #{problems} in #{formula_count} #{formulae}"
   end
 end
 
@@ -279,9 +279,11 @@ class FormulaAuditor
         end
       end
     end
+
     if present.include?("head") && present.include?("head block")
       problem "Should not have both `head` and `head do`"
     end
+
     if present.include?("bottle modifier") && present.include?("bottle block")
       problem "Should not have `bottle :unneeded/:disable` and `bottle do`"
     end
@@ -467,7 +469,7 @@ class FormulaAuditor
 
     # Make sure the formula name plus description is no longer than 80 characters
     # Note full_name includes the name of the tap, while name does not
-    linelength = formula.name.length + ": ".length + desc.length
+    linelength = "#{formula.name}: #{desc}".length
     if linelength > 80
       problem <<-EOS.undent
         Description is too long. \"name: desc\" should be less than 80 characters.
@@ -668,24 +670,26 @@ class FormulaAuditor
     end
 
     revision_map = attributes_map[:revision]
-    if formula.revision.nonzero?
-      if formula.stable
-        if revision_map[formula.stable.version].empty? # check stable spec
-          problem "'revision #{formula.revision}' should be removed"
-        end
-      else # head/devel-only formula
+
+    return if formula.revision.zero?
+
+    if formula.stable
+      if revision_map[formula.stable.version].empty? # check stable spec
         problem "'revision #{formula.revision}' should be removed"
       end
+    else # head/devel-only formula
+      problem "'revision #{formula.revision}' should be removed"
     end
   end
 
   def audit_legacy_patches
     return unless formula.respond_to?(:patches)
     legacy_patches = Patch.normalize_legacy_patches(formula.patches).grep(LegacyPatch)
-    unless legacy_patches.empty?
-      problem "Use the patch DSL instead of defining a 'patches' method"
-      legacy_patches.each { |p| audit_patch(p) }
-    end
+
+    return if legacy_patches.empty?
+
+    problem "Use the patch DSL instead of defining a 'patches' method"
+    legacy_patches.each { |p| audit_patch(p) }
   end
 
   def audit_patch(patch)
@@ -961,61 +965,56 @@ class FormulaAuditor
       problem "Use Language::Node for npm install args"
     end
 
-    if @strict
-      if line =~ /system ((["'])[^"' ]*(?:\s[^"' ]*)+\2)/
-        bad_system = $1
-        unless %w[| < > & ; *].any? { |c| bad_system.include? c }
-          good_system = bad_system.gsub(" ", "\", \"")
-          problem "Use `system #{good_system}` instead of `system #{bad_system}` "
-        end
-      end
+    return unless @strict
 
-      if line =~ /(require ["']formula["'])/
-        problem "`#{$1}` is now unnecessary"
+    if line =~ /system ((["'])[^"' ]*(?:\s[^"' ]*)+\2)/
+      bad_system = $1
+      unless %w[| < > & ; *].any? { |c| bad_system.include? c }
+        good_system = bad_system.gsub(" ", "\", \"")
+        problem "Use `system #{good_system}` instead of `system #{bad_system}` "
       end
+    end
 
-      if line =~ %r{#\{share\}/#{Regexp.escape(formula.name)}[/'"]}
-        problem "Use \#{pkgshare} instead of \#{share}/#{formula.name}"
-      end
+    if line =~ /(require ["']formula["'])/
+      problem "`#{$1}` is now unnecessary"
+    end
 
-      if line =~ %r{share(\s*[/+]\s*)(['"])#{Regexp.escape(formula.name)}(?:\2|/)}
-        problem "Use pkgshare instead of (share#{$1}\"#{formula.name}\")"
-      end
+    if line =~ %r{#\{share\}/#{Regexp.escape(formula.name)}[/'"]}
+      problem "Use \#{pkgshare} instead of \#{share}/#{formula.name}"
+    end
+
+    if line =~ %r{share(\s*[/+]\s*)(['"])#{Regexp.escape(formula.name)}(?:\2|/)}
+      problem "Use pkgshare instead of (share#{$1}\"#{formula.name}\")"
     end
   end
 
   def audit_caveats
-    caveats = formula.caveats.to_s
-
-    if caveats.include?("setuid")
-      problem "Don't recommend setuid in the caveats, suggest sudo instead."
-    end
+    return unless formula.caveats.to_s.include?("setuid")
+    problem "Don't recommend setuid in the caveats, suggest sudo instead."
   end
 
   def audit_reverse_migration
     # Only enforce for new formula being re-added to core and official taps
     return unless @strict
     return unless formula.tap && formula.tap.official?
+    return unless formula.tap.tap_migrations.key?(formula.name)
 
-    if formula.tap.tap_migrations.key?(formula.name)
-      problem <<-EOS.undent
-        #{formula.name} seems to be listed in tap_migrations.json!
-        Please remove #{formula.name} from present tap & tap_migrations.json
-        before submitting it to Homebrew/homebrew-#{formula.tap.repo}.
-      EOS
-    end
+    problem <<-EOS.undent
+      #{formula.name} seems to be listed in tap_migrations.json!
+      Please remove #{formula.name} from present tap & tap_migrations.json
+      before submitting it to Homebrew/homebrew-#{formula.tap.repo}.
+    EOS
   end
 
   def audit_prefix_has_contents
     return unless formula.prefix.directory?
+    return unless Keg.new(formula.prefix).empty_installation?
 
-    if Keg.new(formula.prefix).empty_installation?
-      problem <<-EOS.undent
-        The installation seems to be empty. Please ensure the prefix
-        is set correctly and expected files are installed.
-        The prefix configure/make argument may be case-sensitive.
-      EOS
-    end
+    problem <<-EOS.undent
+      The installation seems to be empty. Please ensure the prefix
+      is set correctly and expected files are installed.
+      The prefix configure/make argument may be case-sensitive.
+    EOS
   end
 
   def audit_conditional_dep(dep, condition, line)
@@ -1184,9 +1183,7 @@ class ResourceAuditor
       end
     end
 
-    using_strategy = DownloadStrategyDetector.detect("", using)
-
-    if url_strategy == using_strategy
+    if url_strategy == DownloadStrategyDetector.detect("", using)
       problem "Redundant :using value in URL"
     end
   end
diff --git a/Library/Homebrew/dev-cmd/bottle.rb b/Library/Homebrew/dev-cmd/bottle.rb
index f4d6a463af..b2aa3b2c50 100644
--- a/Library/Homebrew/dev-cmd/bottle.rb
+++ b/Library/Homebrew/dev-cmd/bottle.rb
@@ -51,10 +51,11 @@ module Homebrew
       end
 
       @put_filenames ||= []
-      unless @put_filenames.include? filename
-        puts "#{Tty.red}#{filename}#{Tty.reset}"
-        @put_filenames << filename
-      end
+
+      return if @put_filenames.include? filename
+
+      puts "#{Tty.red}#{filename}#{Tty.reset}"
+      @put_filenames << filename
     end
 
     result = false
@@ -107,9 +108,7 @@ module Homebrew
     absolute_symlinks_start_with_string = []
     keg.find do |pn|
       next unless pn.symlink? && (link = pn.readlink).absolute?
-      if link.to_s.start_with?(string)
-        absolute_symlinks_start_with_string << pn
-      end
+      absolute_symlinks_start_with_string << pn if link.to_s.start_with?(string)
     end
 
     if ARGV.verbose?
@@ -137,11 +136,11 @@ module Homebrew
     tap = f.tap
 
     unless tap
-      if ARGV.include?("--force-core-tap")
-        tap = CoreTap.instance
-      else
+      unless ARGV.include?("--force-core-tap")
         return ofail "Formula not from core or any taps: #{f.full_name}"
       end
+
+      tap = CoreTap.instance
     end
 
     if f.bottle_disabled?
@@ -154,9 +153,7 @@ module Homebrew
       return ofail "Formula not installed with '--build-bottle': #{f.full_name}"
     end
 
-    unless f.stable
-      return ofail "Formula has no stable version: #{f.full_name}"
-    end
+    return ofail "Formula has no stable version: #{f.full_name}" unless f.stable
 
     if ARGV.include?("--no-rebuild") || !f.tap
       rebuild = 0
@@ -323,34 +320,33 @@ module Homebrew
     puts "./#{filename}"
     puts output
 
-    if ARGV.include? "--json"
-      json = {
-        f.full_name => {
-          "formula" => {
-            "pkg_version" => f.pkg_version.to_s,
-            "path" => f.path.to_s.strip_prefix("#{HOMEBREW_REPOSITORY}/"),
-          },
-          "bottle" => {
-            "root_url" => bottle.root_url,
-            "prefix" => bottle.prefix,
-            "cellar" => bottle.cellar.to_s,
-            "rebuild" => bottle.rebuild,
-            "tags" => {
-              Utils::Bottles.tag.to_s => {
-                "filename" => filename.to_s,
-                "sha256" => sha256,
-              },
+    return unless ARGV.include? "--json"
+    json = {
+      f.full_name => {
+        "formula" => {
+          "pkg_version" => f.pkg_version.to_s,
+          "path" => f.path.to_s.strip_prefix("#{HOMEBREW_REPOSITORY}/"),
+        },
+        "bottle" => {
+          "root_url" => bottle.root_url,
+          "prefix" => bottle.prefix,
+          "cellar" => bottle.cellar.to_s,
+          "rebuild" => bottle.rebuild,
+          "tags" => {
+            Utils::Bottles.tag.to_s => {
+              "filename" => filename.to_s,
+              "sha256" => sha256,
             },
           },
-          "bintray" => {
-            "package" => Utils::Bottles::Bintray.package(f.name),
-            "repository" => Utils::Bottles::Bintray.repository(tap),
-          },
         },
-      }
-      File.open("#{filename.prefix}.bottle.json", "w") do |file|
-        file.write Utils::JSON.dump json
-      end
+        "bintray" => {
+          "package" => Utils::Bottles::Bintray.package(f.name),
+          "repository" => Utils::Bottles::Bintray.repository(tap),
+        },
+      },
+    }
+    File.open("#{filename.prefix}.bottle.json", "w") do |file|
+      file.write Utils::JSON.dump json
     end
   end
 
@@ -436,7 +432,7 @@ module Homebrew
             puts output
             update_or_add = "add"
             if s.include? "stable do"
-              indent = s.slice(/^ +stable do/).length - "stable do".length
+              indent = s.slice(/^( +)stable do/, 1).length
               string = s.sub!(/^ {#{indent}}stable do(.|\n)+?^ {#{indent}}end\n/m, '\0' + output + "\n")
             else
               string = s.sub!(
diff --git a/Library/Homebrew/dev-cmd/edit.rb b/Library/Homebrew/dev-cmd/edit.rb
index f80d058613..2d2a5ec082 100644
--- a/Library/Homebrew/dev-cmd/edit.rb
+++ b/Library/Homebrew/dev-cmd/edit.rb
@@ -33,9 +33,9 @@ module Homebrew
       # Don't use ARGV.formulae as that will throw if the file doesn't parse
       paths = ARGV.named.map do |name|
         path = Formulary.path(name)
-        unless path.file? || ARGV.force?
-          raise FormulaUnavailableError, name
-        end
+
+        raise FormulaUnavailableError, name unless path.file? || ARGV.force?
+
         path
       end
       exec_editor(*paths)
diff --git a/Library/Homebrew/dev-cmd/mirror.rb b/Library/Homebrew/dev-cmd/mirror.rb
index 162008123c..9966163f8f 100644
--- a/Library/Homebrew/dev-cmd/mirror.rb
+++ b/Library/Homebrew/dev-cmd/mirror.rb
@@ -4,9 +4,7 @@
 
 module Homebrew
   def mirror
-    if ARGV.named.empty?
-      odie "This command requires at least formula argument!"
-    end
+    odie "This command requires at least formula argument!" if ARGV.named.empty?
 
     bintray_user = ENV["BINTRAY_USER"]
     bintray_key = ENV["BINTRAY_KEY"]
diff --git a/Library/Homebrew/dev-cmd/pull.rb b/Library/Homebrew/dev-cmd/pull.rb
index 7f027e1594..b06719fb14 100644
--- a/Library/Homebrew/dev-cmd/pull.rb
+++ b/Library/Homebrew/dev-cmd/pull.rb
@@ -41,12 +41,12 @@ require "pkg_version"
 
 module Homebrew
   def pull
-    if ARGV[0] == "--rebase"
-      odie "You meant `git pull --rebase`."
-    end
+    odie "You meant `git pull --rebase`." if ARGV[0] == "--rebase"
+
     if ARGV.named.empty?
       odie "This command requires at least one argument containing a URL or pull request number"
     end
+
     do_bump = ARGV.include?("--bump") && !ARGV.include?("--clean")
 
     # Formulae with affected bottles that were published
@@ -429,9 +429,9 @@ module Homebrew
     # Returns nil if formula is absent or if there was an error reading it
     def self.lookup(name)
       json = Utils.popen_read(HOMEBREW_BREW_FILE, "info", "--json=v1", name)
-      unless $?.success?
-        return nil
-      end
+
+      return nil unless $?.success?
+
       Homebrew.force_utf8!(json)
       FormulaInfoFromJson.new(Utils::JSON.load(json)[0])
     end
diff --git a/Library/Homebrew/dev-cmd/test-bot.rb b/Library/Homebrew/dev-cmd/test-bot.rb
index 7a5853c48a..ba78cdb59b 100644
--- a/Library/Homebrew/dev-cmd/test-bot.rb
+++ b/Library/Homebrew/dev-cmd/test-bot.rb
@@ -185,8 +185,8 @@ module Homebrew
 
     def puts_result
       if ENV["TRAVIS"]
-        travis_start_time = @start_time.to_i*1000000000
-        travis_end_time = @end_time.to_i*1000000000
+        travis_start_time = @start_time.to_i * 1_000_000_000
+        travis_end_time = @end_time.to_i * 1_000_000_000
         travis_duration = travis_end_time - travis_start_time
         puts "#{Tty.white}==>#{Tty.green} PASSED#{Tty.reset}" if passed?
         puts "travis_time:end:#{@travis_timer_id},start=#{travis_start_time},finish=#{travis_end_time},duration=#{travis_duration}"
@@ -563,11 +563,10 @@ module Homebrew
 
       (installed & dependencies).each do |installed_dependency|
         installed_dependency_formula = Formulary.factory(installed_dependency)
-        if installed_dependency_formula.installed? &&
-           !installed_dependency_formula.keg_only? &&
-           !installed_dependency_formula.linked_keg.exist?
-          test "brew", "link", installed_dependency
-        end
+        next unless installed_dependency_formula.installed?
+        next if installed_dependency_formula.keg_only?
+        next if installed_dependency_formula.linked_keg.exist?
+        test "brew", "link", installed_dependency
       end
 
       dependencies -= installed
@@ -725,9 +724,7 @@ module Homebrew
         coverage_args = []
         if ARGV.include?("--coverage")
           if ENV["JENKINS_HOME"]
-            if OS.mac? && MacOS.version == :sierra
-              coverage_args << "--coverage"
-            end
+            coverage_args << "--coverage" if OS.mac? && MacOS.version == :sierra
           else
             coverage_args << "--coverage"
           end
@@ -742,9 +739,7 @@ module Homebrew
           test "brew", "cask-tests", *coverage_args
         end
       elsif @tap
-        if @tap.name == "homebrew/core"
-          test "brew", "style", @tap.name
-        end
+        test "brew", "style", @tap.name if @tap.name == "homebrew/core"
         test "brew", "readall", "--aliases", @tap.name
       end
     end
@@ -1055,9 +1050,7 @@ module Homebrew
       ARGV << "--junit" << "--local" << "--test-default-formula"
     end
 
-    if ARGV.include? "--ci-master"
-      ARGV << "--fast"
-    end
+    ARGV << "--fast" if ARGV.include?("--ci-master")
 
     if ARGV.include? "--local"
       ENV["HOMEBREW_CACHE"] = "#{ENV["HOME"]}/Library/Caches/Homebrew"
@@ -1081,9 +1074,7 @@ module Homebrew
       safe_system "brew", "tap", tap.name, "--full"
     end
 
-    if ARGV.include? "--ci-upload"
-      return test_ci_upload(tap)
-    end
+    return test_ci_upload(tap) if ARGV.include?("--ci-upload")
 
     tests = []
     any_errors = false
diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 650ff3eab5..743c653d22 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -39,15 +39,11 @@ module Homebrew
         vols = get_mounts path
 
         # no volume found
-        if vols.empty?
-          return -1
-        end
+        return -1 if vols.empty?
 
         vol_index = @volumes.index(vols[0])
         # volume not found in volume list
-        if vol_index.nil?
-          return -1
-        end
+        return -1 if vol_index.nil?
         vol_index
       end
 
@@ -82,8 +78,8 @@ module Homebrew
         end
       end
 
-      def inject_file_list(list, str)
-        list.inject(str) { |s, f| s << "    #{f}\n" }
+      def inject_file_list(list, string)
+        list.inject(string) { |a, e| a << "    #{e}\n" }
       end
       ############# END HELPERS
 
@@ -599,7 +595,7 @@ module Homebrew
         EOS
       end
 
-      def check_DYLD_vars
+      def check_dyld_vars
         dyld_vars = ENV.keys.grep(/^DYLD_/)
         return if dyld_vars.empty?
 
@@ -758,7 +754,7 @@ module Homebrew
               cd #{HOMEBREW_REPOSITORY}
               git remote add origin https://github.com/Homebrew/brew.git
           EOS
-        elsif origin !~ /Homebrew\/brew(\.git)?$/
+        elsif origin !~ %r{Homebrew/brew(\.git)?$}
           <<-EOS.undent
             Suspicious git origin remote found.
 
diff --git a/Library/Homebrew/download_strategy.rb b/Library/Homebrew/download_strategy.rb
index cabb22c228..d19d131a75 100644
--- a/Library/Homebrew/download_strategy.rb
+++ b/Library/Homebrew/download_strategy.rb
@@ -663,19 +663,19 @@ class GitDownloadStrategy < VCSDownloadStrategy
     @shallow && support_depth?
   end
 
-  def is_shallow_clone?
+  def shallow_dir?
     git_dir.join("shallow").exist?
   end
 
   def support_depth?
-    @ref_type != :revision && SHALLOW_CLONE_WHITELIST.any? { |rx| rx === @url }
+    @ref_type != :revision && SHALLOW_CLONE_WHITELIST.any? { |regex| @url =~ regex }
   end
 
   def git_dir
     cached_location.join(".git")
   end
 
-  def has_ref?
+  def ref?
     quiet_system "git", "--git-dir", git_dir, "rev-parse", "-q", "--verify", "#{@ref}^{commit}"
   end
 
@@ -696,7 +696,8 @@ class GitDownloadStrategy < VCSDownloadStrategy
     args << "--depth" << "1" if shallow_clone?
 
     case @ref_type
-    when :branch, :tag then args << "--branch" << @ref
+    when :branch, :tag
+      args << "--branch" << @ref
     end
 
     args << @url << cached_location
@@ -716,8 +717,8 @@ class GitDownloadStrategy < VCSDownloadStrategy
   end
 
   def update_repo
-    if @ref_type == :branch || !has_ref?
-      if !shallow_clone? && is_shallow_clone?
+    if @ref_type == :branch || !ref?
+      if !shallow_clone? && shallow_dir?
         quiet_safe_system "git", "fetch", "origin", "--unshallow"
       else
         quiet_safe_system "git", "fetch", "origin"
@@ -741,9 +742,11 @@ class GitDownloadStrategy < VCSDownloadStrategy
 
   def reset_args
     ref = case @ref_type
-          when :branch then "origin/#{@ref}"
-          when :revision, :tag then @ref
-          end
+    when :branch
+      "origin/#{@ref}"
+    when :revision, :tag
+      @ref
+    end
 
     %W[reset --hard #{ref}]
   end
@@ -1021,9 +1024,9 @@ class DownloadStrategyDetector
   def self.detect(url, strategy = nil)
     if strategy.nil?
       detect_from_url(url)
-    elsif Class === strategy && strategy < AbstractDownloadStrategy
+    elsif strategy.is_a?(Class) && strategy < AbstractDownloadStrategy
       strategy
-    elsif Symbol === strategy
+    elsif strategy.is_a?(Symbol)
       detect_from_symbol(strategy)
     else
       raise TypeError,
diff --git a/Library/Homebrew/extend/ARGV.rb b/Library/Homebrew/extend/ARGV.rb
index d9f5998771..92b4cb898e 100644
--- a/Library/Homebrew/extend/ARGV.rb
+++ b/Library/Homebrew/extend/ARGV.rb
@@ -216,7 +216,7 @@ module HomebrewArgvExtension
   end
 
   def build_all_from_source?
-    !!ENV["HOMEBREW_BUILD_FROM_SOURCE"]
+    !ENV["HOMEBREW_BUILD_FROM_SOURCE"].nil?
   end
 
   # Whether a given formula should be built from source during the current
diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index a9b2358b13..c1111b840f 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -192,15 +192,11 @@ module Stdenv
   end
 
   def libcxx
-    if compiler == :clang
-      append "CXX", "-stdlib=libc++"
-    end
+    append "CXX", "-stdlib=libc++" if compiler == :clang
   end
 
   def libstdcxx
-    if compiler == :clang
-      append "CXX", "-stdlib=libstdc++"
-    end
+    append "CXX", "-stdlib=libstdc++" if compiler == :clang
   end
 
   # @private
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index 4169905dfa..39ff4b8f8e 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -64,9 +64,7 @@ module Superenv
     self["HOMEBREW_INCLUDE_PATHS"] = determine_include_paths
     self["HOMEBREW_LIBRARY_PATHS"] = determine_library_paths
     self["HOMEBREW_DEPENDENCIES"] = determine_dependencies
-    unless formula.nil?
-      self["HOMEBREW_FORMULA_PREFIX"] = formula.prefix
-    end
+    self["HOMEBREW_FORMULA_PREFIX"] = formula.prefix unless formula.nil?
 
     # The HOMEBREW_CCCFG ENV variable is used by the ENV/cc tool to control
     # compiler flag stripping. It consists of a string of characters which act
diff --git a/Library/Homebrew/extend/os/blacklist.rb b/Library/Homebrew/extend/os/blacklist.rb
index f72c7c6438..932040f825 100644
--- a/Library/Homebrew/extend/os/blacklist.rb
+++ b/Library/Homebrew/extend/os/blacklist.rb
@@ -1,5 +1,2 @@
 require "blacklist"
-
-if OS.mac?
-  require "extend/os/mac/blacklist"
-end
+require "extend/os/mac/blacklist" if OS.mac?
diff --git a/Library/Homebrew/extend/os/bottles.rb b/Library/Homebrew/extend/os/bottles.rb
index aff9300de1..146b807a4a 100644
--- a/Library/Homebrew/extend/os/bottles.rb
+++ b/Library/Homebrew/extend/os/bottles.rb
@@ -1,5 +1,2 @@
 require "utils/bottles"
-
-if OS.mac?
-  require "extend/os/mac/utils/bottles"
-end
+require "extend/os/mac/utils/bottles" if OS.mac?
diff --git a/Library/Homebrew/extend/os/cleaner.rb b/Library/Homebrew/extend/os/cleaner.rb
index 868ff2d335..6b94cdf5a5 100644
--- a/Library/Homebrew/extend/os/cleaner.rb
+++ b/Library/Homebrew/extend/os/cleaner.rb
@@ -1,5 +1,2 @@
 require "cleaner"
-
-if OS.mac?
-  require "extend/os/mac/cleaner"
-end
+require "extend/os/mac/cleaner" if OS.mac?
diff --git a/Library/Homebrew/extend/os/dependency_collector.rb b/Library/Homebrew/extend/os/dependency_collector.rb
index d295263f62..56fcad31d0 100644
--- a/Library/Homebrew/extend/os/dependency_collector.rb
+++ b/Library/Homebrew/extend/os/dependency_collector.rb
@@ -1,5 +1,2 @@
 require "dependency_collector"
-
-if OS.mac?
-  require "extend/os/mac/dependency_collector"
-end
+require "extend/os/mac/dependency_collector" if OS.mac?
diff --git a/Library/Homebrew/extend/os/development_tools.rb b/Library/Homebrew/extend/os/development_tools.rb
index 7b590dc8b6..5bd5cb81a0 100644
--- a/Library/Homebrew/extend/os/development_tools.rb
+++ b/Library/Homebrew/extend/os/development_tools.rb
@@ -1,5 +1,2 @@
 require "development_tools"
-
-if OS.mac?
-  require "extend/os/mac/development_tools"
-end
+require "extend/os/mac/development_tools" if OS.mac?
diff --git a/Library/Homebrew/extend/os/diagnostic.rb b/Library/Homebrew/extend/os/diagnostic.rb
index 0c844743b6..f8f53b1f4f 100644
--- a/Library/Homebrew/extend/os/diagnostic.rb
+++ b/Library/Homebrew/extend/os/diagnostic.rb
@@ -1,5 +1,2 @@
 require "diagnostic"
-
-if OS.mac?
-  require "extend/os/mac/diagnostic"
-end
+require "extend/os/mac/diagnostic" if OS.mac?
diff --git a/Library/Homebrew/extend/os/emoji.rb b/Library/Homebrew/extend/os/emoji.rb
index fe3e7f44e5..8fd99e1d3e 100644
--- a/Library/Homebrew/extend/os/emoji.rb
+++ b/Library/Homebrew/extend/os/emoji.rb
@@ -1,6 +1,3 @@
 require "os"
 require "emoji"
-
-if OS.mac?
-  require "extend/os/mac/emoji"
-end
+require "extend/os/mac/emoji" if OS.mac?
diff --git a/Library/Homebrew/extend/os/extend/ENV/shared.rb b/Library/Homebrew/extend/os/extend/ENV/shared.rb
index 676159b37a..e9574eb583 100644
--- a/Library/Homebrew/extend/os/extend/ENV/shared.rb
+++ b/Library/Homebrew/extend/os/extend/ENV/shared.rb
@@ -1,5 +1,2 @@
 require "extend/ENV/shared"
-
-if OS.mac?
-  require "extend/os/mac/extend/ENV/shared"
-end
+require "extend/os/mac/extend/ENV/shared" if OS.mac?
diff --git a/Library/Homebrew/extend/os/extend/ENV/std.rb b/Library/Homebrew/extend/os/extend/ENV/std.rb
index 320f9981f6..8e6b13a61e 100644
--- a/Library/Homebrew/extend/os/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/os/extend/ENV/std.rb
@@ -1,5 +1,2 @@
 require "extend/ENV/std"
-
-if OS.mac?
-  require "extend/os/mac/extend/ENV/std"
-end
+require "extend/os/mac/extend/ENV/std" if OS.mac?
diff --git a/Library/Homebrew/extend/os/extend/ENV/super.rb b/Library/Homebrew/extend/os/extend/ENV/super.rb
index fd4e93c227..27c49eb849 100644
--- a/Library/Homebrew/extend/os/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/os/extend/ENV/super.rb
@@ -1,5 +1,2 @@
 require "extend/ENV/super"
-
-if OS.mac?
-  require "extend/os/mac/extend/ENV/super"
-end
+require "extend/os/mac/extend/ENV/super" if OS.mac?
diff --git a/Library/Homebrew/extend/os/formula_cellar_checks.rb b/Library/Homebrew/extend/os/formula_cellar_checks.rb
index 4e30cd7910..66b5b80d3d 100644
--- a/Library/Homebrew/extend/os/formula_cellar_checks.rb
+++ b/Library/Homebrew/extend/os/formula_cellar_checks.rb
@@ -1,5 +1,2 @@
 require "formula_cellar_checks"
-
-if OS.mac?
-  require "extend/os/mac/formula_cellar_checks"
-end
+require "extend/os/mac/formula_cellar_checks" if OS.mac?
diff --git a/Library/Homebrew/extend/os/keg_relocate.rb b/Library/Homebrew/extend/os/keg_relocate.rb
index 2fde45d93a..25a74286a4 100644
--- a/Library/Homebrew/extend/os/keg_relocate.rb
+++ b/Library/Homebrew/extend/os/keg_relocate.rb
@@ -1,5 +1,2 @@
 require "keg_relocate"
-
-if OS.mac?
-  require "extend/os/mac/keg_relocate"
-end
+require "extend/os/mac/keg_relocate" if OS.mac?
diff --git a/Library/Homebrew/extend/os/mac/extend/ENV/shared.rb b/Library/Homebrew/extend/os/mac/extend/ENV/shared.rb
index 8662040243..67a3944c39 100644
--- a/Library/Homebrew/extend/os/mac/extend/ENV/shared.rb
+++ b/Library/Homebrew/extend/os/mac/extend/ENV/shared.rb
@@ -2,13 +2,8 @@ module SharedEnvExtension
   def no_weak_imports_support?
     return false unless compiler == :clang
 
-    if MacOS::Xcode.version && MacOS::Xcode.version < "8.0"
-      return false
-    end
-
-    if MacOS::CLT.version && MacOS::CLT.version < "8.0"
-      return false
-    end
+    return false if MacOS::Xcode.version && MacOS::Xcode.version < "8.0"
+    return false if MacOS::CLT.version && MacOS::CLT.version < "8.0"
 
     true
   end
diff --git a/Library/Homebrew/extend/os/system_config.rb b/Library/Homebrew/extend/os/system_config.rb
index cf7b69cb68..edc0071665 100644
--- a/Library/Homebrew/extend/os/system_config.rb
+++ b/Library/Homebrew/extend/os/system_config.rb
@@ -1,5 +1,2 @@
 require "system_config"
-
-if OS.mac?
-  require "extend/os/mac/system_config"
-end
+require "extend/os/mac/system_config" if OS.mac?
diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 5dce906b98..68029dc387 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -71,13 +71,13 @@ class Pathname
       when Array
         if src.empty?
           opoo "tried to install empty array to #{self}"
-          return
+          break
         end
         src.each { |s| install_p(s, File.basename(s)) }
       when Hash
         if src.empty?
           opoo "tried to install empty hash to #{self}"
-          return
+          break
         end
         src.each { |s, new_basename| install_p(s, new_basename) }
       else
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 4b3ef33f27..7a5584cdfe 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -395,9 +395,7 @@ class Formula
   def oldname
     @oldname ||= if tap
       formula_renames = tap.formula_renames
-      if formula_renames.value?(name)
-        formula_renames.to_a.rassoc(name).first
-      end
+      formula_renames.to_a.rassoc(name).first if formula_renames.value?(name)
     end
   end
 
@@ -1052,7 +1050,7 @@ class Formula
     self.class.link_overwrite_paths.any? do |p|
       p == to_check ||
         to_check.start_with?(p.chomp("/") + "/") ||
-        /^#{Regexp.escape(p).gsub('\*', ".*?")}$/ === to_check
+        to_check =~ /^#{Regexp.escape(p).gsub('\*', ".*?")}$/
     end
   end
 
@@ -1246,7 +1244,7 @@ class Formula
 
   # @private
   def <=>(other)
-    return unless Formula === other
+    return unless other.is_a?(Formula)
     name <=> other.name
   end
 
@@ -1776,9 +1774,7 @@ class Formula
     ENV["HOMEBREW_CC_LOG_PATH"] = logfn
 
     # TODO: system "xcodebuild" is deprecated, this should be removed soon.
-    if cmd.to_s.start_with? "xcodebuild"
-      ENV.remove_cc_etc
-    end
+    ENV.remove_cc_etc if cmd.to_s.start_with? "xcodebuild"
 
     # Turn on argument filtering in the superenv compiler wrapper.
     # We should probably have a better mechanism for this than adding
@@ -1786,9 +1782,7 @@ class Formula
     if cmd == "python"
       setup_py_in_args = %w[setup.py build.py].include?(args.first)
       setuptools_shim_in_args = args.any? { |a| a.to_s.start_with? "import setuptools" }
-      if setup_py_in_args || setuptools_shim_in_args
-        ENV.refurbish_args
-      end
+      ENV.refurbish_args if setup_py_in_args || setuptools_shim_in_args
     end
 
     $stdout.reopen(out)
@@ -2226,7 +2220,7 @@ class Formula
     # If this formula conflicts with another one.
     # <pre>conflicts_with "imagemagick", :because => "because this is just a stupid example"</pre>
     def conflicts_with(*names)
-      opts = Hash === names.last ? names.pop : {}
+      opts = names.last.is_a?(Hash) ? names.pop : {}
       names.each { |name| conflicts << FormulaConflict.new(name, opts[:because]) }
     end
 
diff --git a/Library/Homebrew/formula_cellar_checks.rb b/Library/Homebrew/formula_cellar_checks.rb
index 3805d0f45c..89757dfb27 100644
--- a/Library/Homebrew/formula_cellar_checks.rb
+++ b/Library/Homebrew/formula_cellar_checks.rb
@@ -1,7 +1,7 @@
 require "utils/shell"
 
 module FormulaCellarChecks
-  def check_PATH(bin)
+  def check_env_path(bin)
     # warn the user if stuff was installed outside of their PATH
     return unless bin.directory?
     return if bin.children.empty?
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index f64b77026d..6e8f2e3b75 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -24,7 +24,9 @@ class FormulaInstaller
     private(*names)
     names.each do |name|
       predicate = "#{name}?"
-      define_method(predicate) { !!send(name) }
+      define_method(predicate) do
+        send(name) ? true : false
+      end
       private(predicate)
     end
   end
@@ -71,7 +73,8 @@ class FormulaInstaller
   end
 
   def build_bottle?
-    !!@build_bottle && !formula.bottle_disabled?
+    return false unless @build_bottle
+    !formula.bottle_disabled?
   end
 
   def pour_bottle?(install_bottle_options = { warn: false })
@@ -254,9 +257,7 @@ class FormulaInstaller
 
     unless @poured_bottle
       not_pouring = !pour_bottle || @pour_failed
-      if not_pouring && !ignore_deps?
-        compute_and_install_dependencies
-      end
+      compute_and_install_dependencies if not_pouring && !ignore_deps?
       build
       clean
     end
@@ -543,7 +544,7 @@ class FormulaInstaller
     @build_time ||= Time.now - @start_time if @start_time && !interactive?
   end
 
-  def sanitized_ARGV_options
+  def sanitized_argv_options
     args = []
     args << "--ignore-dependencies" if ignore_deps?
 
@@ -582,7 +583,7 @@ class FormulaInstaller
   end
 
   def build_argv
-    sanitized_ARGV_options + options.as_flags
+    sanitized_argv_options + options.as_flags
   end
 
   def build
@@ -810,8 +811,8 @@ class FormulaInstaller
   end
 
   def audit_installed
-    audit_check_output(check_PATH(formula.bin))
-    audit_check_output(check_PATH(formula.sbin))
+    audit_check_output(check_env_path(formula.bin))
+    audit_check_output(check_env_path(formula.sbin))
     super
   end
 
diff --git a/Library/Homebrew/formula_lock.rb b/Library/Homebrew/formula_lock.rb
index 1ce62b328f..8743eaef8c 100644
--- a/Library/Homebrew/formula_lock.rb
+++ b/Library/Homebrew/formula_lock.rb
@@ -35,9 +35,8 @@ class FormulaLock
     if @lockfile.nil? || @lockfile.closed?
       @lockfile = @path.open(File::RDWR | File::CREAT)
       @lockfile.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
-      @lockfile
-    else
-      @lockfile
     end
+
+    @lockfile
   end
 end
diff --git a/Library/Homebrew/formula_versions.rb b/Library/Homebrew/formula_versions.rb
index ec2e2a459f..81e15d314f 100644
--- a/Library/Homebrew/formula_versions.rb
+++ b/Library/Homebrew/formula_versions.rb
@@ -52,9 +52,7 @@ class FormulaVersions
     rev_list(branch) do |rev|
       formula_at_revision(rev) do |f|
         bottle = f.bottle_specification
-        unless bottle.checksums.empty?
-          map[f.pkg_version] << bottle.rebuild
-        end
+        map[f.pkg_version] << bottle.rebuild unless bottle.checksums.empty?
       end
     end
     map
diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 74f6694135..a6ec45d3c0 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -301,9 +301,7 @@ class Formulary
       return TapLoader.new(ref)
     end
 
-    if File.extname(ref) == ".rb"
-      return FromPathLoader.new(ref)
-    end
+    return FromPathLoader.new(ref) if File.extname(ref) == ".rb"
 
     formula_with_that_name = core_path(ref)
     if formula_with_that_name.file?
@@ -311,9 +309,7 @@ class Formulary
     end
 
     possible_alias = CoreTap.instance.alias_dir/ref
-    if possible_alias.file?
-      return AliasLoader.new(possible_alias)
-    end
+    return AliasLoader.new(possible_alias) if possible_alias.file?
 
     possible_tap_formulae = tap_paths(ref)
     if possible_tap_formulae.size > 1
diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index ecbc4c6e00..65ce6480a6 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -62,12 +62,17 @@ class Keg
   end
 
   # locale-specific directories have the form language[_territory][.codeset][@modifier]
-  LOCALEDIR_RX = /(locale|man)\/([a-z]{2}|C|POSIX)(_[A-Z]{2})?(\.[a-zA-Z\-0-9]+(@.+)?)?/
+  LOCALEDIR_RX = %r{(locale|man)/([a-z]{2}|C|POSIX)(_[A-Z]{2})?(\.[a-zA-Z\-0-9]+(@.+)?)?}
   INFOFILE_RX = %r{info/([^.].*?\.info|dir)$}
   TOP_LEVEL_DIRECTORIES = %w[bin etc include lib sbin share var Frameworks].freeze
   ALL_TOP_LEVEL_DIRECTORIES = (TOP_LEVEL_DIRECTORIES + %w[lib/pkgconfig share/locale share/man opt]).freeze
-  PRUNEABLE_DIRECTORIES = %w[bin etc include lib sbin share Frameworks LinkedKegs var/homebrew/linked].map do |d|
-    case d when "LinkedKegs" then HOMEBREW_LIBRARY/d else HOMEBREW_PREFIX/d end
+  PRUNEABLE_DIRECTORIES = %w[bin etc include lib sbin share Frameworks LinkedKegs var/homebrew/linked].map do |dir|
+    case dir
+    when "LinkedKegs"
+      HOMEBREW_LIBRARY/dir
+    else
+      HOMEBREW_PREFIX/dir
+    end
   end
 
   # These paths relative to the keg's share directory should always be real
@@ -249,10 +254,10 @@ class Keg
 
   def completion_installed?(shell)
     dir = case shell
-          when :bash then path.join("etc", "bash_completion.d")
-          when :zsh  then path.join("share", "zsh", "site-functions")
-          when :fish then path.join("share", "fish", "vendor_completions.d")
-          end
+    when :bash then path.join("etc", "bash_completion.d")
+    when :zsh  then path.join("share", "zsh", "site-functions")
+    when :fish then path.join("share", "fish", "vendor_completions.d")
+    end
     dir && dir.directory? && !dir.children.empty?
   end
 
@@ -318,13 +323,13 @@ class Keg
       when "locale/locale.alias" then :skip_file
       when INFOFILE_RX then :info
       when LOCALEDIR_RX then :mkpath
-      when /^icons\/.*\/icon-theme\.cache$/ then :skip_file
+      when %r{^icons/.*/icon-theme\.cache$} then :skip_file
       # all icons subfolders should also mkpath
-      when /^icons\// then :mkpath
+      when %r{^icons/} then :mkpath
       when /^zsh/ then :mkpath
       when /^fish/ then :mkpath
       # Lua, Lua51, Lua53 all need the same handling.
-      when /^lua\// then :mkpath
+      when %r{^lua/} then :mkpath
       when %r{^guile/} then :mkpath
       when *SHARE_PATHS then :mkpath
       else :link
@@ -362,7 +367,7 @@ class Keg
       # the :link strategy. However, for Foo.framework and
       # Foo.framework/Versions we have to use :mkpath so that multiple formulae
       # can link their versions into it and `brew [un]link` works.
-      if relative_path.to_s =~ /[^\/]*\.framework(\/Versions)?$/
+      if relative_path.to_s =~ %r{[^/]*\.framework(/Versions)?$}
         :mkpath
       else
         :link
diff --git a/Library/Homebrew/language/haskell.rb b/Library/Homebrew/language/haskell.rb
index b5d0e1220b..4b7f88a999 100644
--- a/Library/Homebrew/language/haskell.rb
+++ b/Library/Homebrew/language/haskell.rb
@@ -79,19 +79,16 @@ module Language
 
           # if we have build flags, we have to pass them to cabal install to resolve the necessary
           # dependencies, and call cabal configure afterwards to set the flags again for compile
-          flags = ""
-          if options[:flags]
-            flags = "--flags=#{options[:flags].join(" ")}"
-          end
+          flags = "--flags=#{options[:flags].join(" ")}" if options[:flags]
 
           args_and_flags = args
-          args_and_flags << flags unless flags.empty?
+          args_and_flags << flags unless flags.nil?
 
           # install dependencies in the sandbox
           cabal_install "--only-dependencies", *args_and_flags
 
           # call configure if build flags are set
-          cabal_configure flags unless flags.empty?
+          cabal_configure flags unless flags.nil?
 
           # install the main package in the destination dir
           cabal_install "--prefix=#{prefix}", *args
diff --git a/Library/Homebrew/migrator.rb b/Library/Homebrew/migrator.rb
index d31025119e..d8c06de1af 100644
--- a/Library/Homebrew/migrator.rb
+++ b/Library/Homebrew/migrator.rb
@@ -337,9 +337,7 @@ class Migrator
   end
 
   def backup_oldname_cellar
-    unless old_cellar.exist?
-      FileUtils.mv(new_cellar, old_cellar)
-    end
+    FileUtils.mv(new_cellar, old_cellar) unless old_cellar.exist?
   end
 
   def backup_old_tabs
diff --git a/Library/Homebrew/options.rb b/Library/Homebrew/options.rb
index 1d92fbf47b..947ce5acd5 100644
--- a/Library/Homebrew/options.rb
+++ b/Library/Homebrew/options.rb
@@ -14,7 +14,7 @@ class Option
   end
 
   def <=>(other)
-    return unless Option === other
+    return unless other.is_a?(Option)
     name <=> other.name
   end
 
diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 3aab9bf523..dac8b8f1eb 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -175,7 +175,7 @@ module OS
       # Returns true even if outdated tools are installed, e.g.
       # tools from Xcode 4.x on 10.9
       def installed?
-        !!detect_version
+        !detect_version.nil?
       end
 
       def update_instructions
diff --git a/Library/Homebrew/patch.rb b/Library/Homebrew/patch.rb
index 1148389cfe..74e58e526d 100644
--- a/Library/Homebrew/patch.rb
+++ b/Library/Homebrew/patch.rb
@@ -89,7 +89,7 @@ class DATAPatch < EmbeddedPatch
     path.open("rb") do |f|
       begin
         line = f.gets
-      end until line.nil? || /^__END__$/ === line
+      end until line.nil? || line =~ /^__END__$/
       data << line while line = f.gets
     end
     data
diff --git a/Library/Homebrew/pkg_version.rb b/Library/Homebrew/pkg_version.rb
index 4bf701f357..2868508e39 100644
--- a/Library/Homebrew/pkg_version.rb
+++ b/Library/Homebrew/pkg_version.rb
@@ -32,7 +32,7 @@ class PkgVersion
   alias_method :to_str, :to_s
 
   def <=>(other)
-    return unless PkgVersion === other
+    return unless other.is_a?(PkgVersion)
     (version <=> other.version).nonzero? || revision <=> other.revision
   end
   alias_method :eql?, :==
diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
index 4ea15774db..69cdec17fe 100644
--- a/Library/Homebrew/requirement.rb
+++ b/Library/Homebrew/requirement.rb
@@ -56,7 +56,7 @@ class Requirement
   def satisfied?
     result = self.class.satisfy.yielder { |p| instance_eval(&p) }
     @satisfied_result = result
-    !!result
+    result ? true : false
   end
 
   # Overriding #fatal? is deprecated.
@@ -83,7 +83,7 @@ class Requirement
     # PATH.
     # This is undocumented magic and it should be removed, but we need to add
     # a way to declare path-based requirements that work with superenv first.
-    if Pathname === @satisfied_result
+    if @satisfied_result.is_a?(Pathname)
       parent = @satisfied_result.parent
       unless ENV["PATH"].split(File::PATH_SEPARATOR).include?(parent.to_s)
         ENV.append_path("PATH", parent)
@@ -115,7 +115,7 @@ class Requirement
   def to_dependency
     f = self.class.default_formula
     raise "No default formula defined for #{inspect}" if f.nil?
-    if HOMEBREW_TAP_FORMULA_REGEX === f
+    if f =~ HOMEBREW_TAP_FORMULA_REGEX
       TapDependency.new(f, tags, method(:modify_build_environment), name)
     else
       Dependency.new(f, tags, method(:modify_build_environment), name)
diff --git a/Library/Homebrew/requirements.rb b/Library/Homebrew/requirements.rb
index 68d21a2b7a..274ba5c9b8 100644
--- a/Library/Homebrew/requirements.rb
+++ b/Library/Homebrew/requirements.rb
@@ -22,7 +22,7 @@ class XcodeRequirement < Requirement
   satisfy(build_env: false) { xcode_installed_version }
 
   def initialize(tags)
-    @version = tags.find { |t| tags.delete(t) if /(\d\.)+\d/ === t }
+    @version = tags.find { |tag| tags.delete(tag) if tag =~ /(\d\.)+\d/ }
     super
   end
 
@@ -39,11 +39,11 @@ class XcodeRequirement < Requirement
       Installing just the Command Line Tools is not sufficient.
     EOS
     if MacOS.version >= :lion
-      message += <<-EOS.undent
+      message + <<-EOS.undent
         Xcode can be installed from the App Store.
       EOS
     else
-      message += <<-EOS.undent
+      message + <<-EOS.undent
         Xcode can be installed from https://developer.apple.com/xcode/downloads/
       EOS
     end
diff --git a/Library/Homebrew/software_spec.rb b/Library/Homebrew/software_spec.rb
index 986dc5354d..25373c322c 100644
--- a/Library/Homebrew/software_spec.rb
+++ b/Library/Homebrew/software_spec.rb
@@ -65,11 +65,12 @@ class SoftwareSpec
   end
 
   def bottle_unneeded?
-    !!@bottle_disable_reason && @bottle_disable_reason.unneeded?
+    return false unless @bottle_disable_reason
+    @bottle_disable_reason.unneeded?
   end
 
   def bottle_disabled?
-    !!@bottle_disable_reason
+    @bottle_disable_reason ? true : false
   end
 
   attr_reader :bottle_disable_reason
@@ -116,12 +117,12 @@ class SoftwareSpec
 
   def option(name, description = "")
     opt = PREDEFINED_OPTIONS.fetch(name) do
-      if Symbol === name
+      if name.is_a?(Symbol)
         opoo "Passing arbitrary symbols to `option` is deprecated: #{name.inspect}"
         puts "Symbols are reserved for future use, please pass a string instead"
         name = name.to_s
       end
-      unless String === name
+      unless name.is_a?(String)
         raise ArgumentError, "option name must be string or symbol; got a #{name.class}: #{name}"
       end
       raise ArgumentError, "option name is required" if name.empty?
@@ -318,7 +319,7 @@ class BottleSpecification
   end
 
   def tag?(tag)
-    !!checksum_for(tag)
+    checksum_for(tag) ? true : false
   end
 
   # Checksum methods in the DSL's bottle block optionally take
diff --git a/Library/Homebrew/tab.rb b/Library/Homebrew/tab.rb
index 12b23cc734..379f2e8a42 100644
--- a/Library/Homebrew/tab.rb
+++ b/Library/Homebrew/tab.rb
@@ -328,9 +328,9 @@ class Tab < OpenStruct
     else
       s << "Built from source"
     end
-    if time
-      s << Time.at(time).strftime("on %Y-%m-%d at %H:%M:%S")
-    end
+
+    s << Time.at(time).strftime("on %Y-%m-%d at %H:%M:%S") if time
+
     unless used_options.empty?
       s << "with:"
       s << used_options.to_a.join(" ")
diff --git a/Library/Homebrew/test/test_diagnostic.rb b/Library/Homebrew/test/test_diagnostic.rb
index 5d0f5f386f..37f56e961b 100644
--- a/Library/Homebrew/test/test_diagnostic.rb
+++ b/Library/Homebrew/test/test_diagnostic.rb
@@ -154,7 +154,7 @@ class DiagnosticChecksTest < Homebrew::TestCase
   def test_check_dyld_vars
     ENV["DYLD_INSERT_LIBRARIES"] = "foo"
     assert_match "Setting DYLD_INSERT_LIBRARIES",
-      @checks.check_DYLD_vars
+      @checks.check_dyld_vars
   end
 
   def test_check_for_symlinked_cellar
diff --git a/Library/Homebrew/test/test_download_strategies.rb b/Library/Homebrew/test/test_download_strategies.rb
index d107d14e8c..87218fb12b 100644
--- a/Library/Homebrew/test/test_download_strategies.rb
+++ b/Library/Homebrew/test/test_download_strategies.rb
@@ -118,7 +118,7 @@ class GitDownloadStrategyTests < Homebrew::TestCase
 
   def test_source_modified_time
     setup_git_repo
-    assert_equal 1242860651, @strategy.source_modified_time.to_i
+    assert_equal 1_242_860_651, @strategy.source_modified_time.to_i
   end
 
   def test_last_commit
diff --git a/Library/Homebrew/test/test_pathname.rb b/Library/Homebrew/test/test_pathname.rb
index 0cd2876d02..492c09c67a 100644
--- a/Library/Homebrew/test/test_pathname.rb
+++ b/Library/Homebrew/test/test_pathname.rb
@@ -26,7 +26,7 @@ class PathnameTests < Homebrew::TestCase
     mkdir_p @dir/"a-directory"
     touch @dir/".DS_Store"
     touch @dir/"a-file"
-    File.truncate(@dir/"a-file", 1048576)
+    File.truncate(@dir/"a-file", 1_048_576)
     ln_s @dir/"a-file", @dir/"a-symlink"
     ln @dir/"a-file", @dir/"a-hardlink"
     assert_equal 3, @dir.file_count
diff --git a/Library/Homebrew/utils/git.rb b/Library/Homebrew/utils/git.rb
index 837cc22e41..dfe47f890f 100644
--- a/Library/Homebrew/utils/git.rb
+++ b/Library/Homebrew/utils/git.rb
@@ -22,9 +22,7 @@ module Utils
     return if git_available?
 
     # we cannot install brewed git if homebrew/core is unavailable.
-    unless CoreTap.instance.installed?
-      raise "Git is unavailable"
-    end
+    raise "Git is unavailable" unless CoreTap.instance.installed?
 
     begin
       oh1 "Installing git"
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 520db66268..c0e5324eaa 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -208,7 +208,7 @@ class Version
   end
 
   def <=>(other)
-    return unless Version === other
+    return unless other.is_a?(Version)
     return 0 if version == other.version
     return 1 if head? && !other.head?
     return -1 if !head? && other.head?
@@ -386,7 +386,7 @@ class Version
 
     # e.g. http://mirrors.jenkins-ci.org/war/1.486/jenkins.war
     # e.g. https://github.com/foo/bar/releases/download/0.10.11/bar.phar
-    m = /\/(\d\.\d+(\.\d+)?)\//.match(spec_s)
+    m = %r{/(\d\.\d+(\.\d+)?)}.match(spec_s)
     return m.captures.first unless m.nil?
 
     # e.g. http://www.ijg.org/files/jpegsrc.v8d.tar.gz