Use ActiveSupport Object#blank? and #present?

Library/Homebrew/cask/cmd/doctor.rb

@@ -75,7 +75,7 @@ module Cask
 
         ohai "Homebrew Cask Taps:"
         [default_tap, *alt_taps].each do |tap|
-          if tap.path.nil? || tap.path.to_s.empty?
+          if tap.path.blank?
             puts none_string
           else
             puts "#{tap.path} (#{cask_count_for_tap(tap)})"

Library/Homebrew/dev-cmd/audit.rb

@@ -961,7 +961,7 @@ module Homebrew
     def audit_version
       if version.nil?
         problem "missing version"
-      elsif version.to_s.empty?
+      elsif version.blank?
         problem "version is set to an empty string"
       elsif !version.detected_from_url?
         version_text = version

Library/Homebrew/dev-cmd/bottle.rb

@@ -453,7 +453,7 @@ module Homebrew
                 tag = tag.to_s.delete ":"
 
                 unless tag.empty?
-                  if !bottle_hash["bottle"]["tags"][tag].to_s.empty?
+                  if bottle_hash["bottle"]["tags"][tag].present?
                     mismatches << "#{key} => #{tag}"
                   else
                     bottle.send(key, old_value => tag.to_sym)

Library/Homebrew/download_strategy.rb

@@ -1109,7 +1109,7 @@ class BazaarDownloadStrategy < VCSDownloadStrategy
   def source_modified_time
     out, = system_command("bzr", args: ["log", "-l", "1", "--timezone=utc", cached_location])
     timestamp = out.chomp
-    raise "Could not get any timestamps from bzr!" if timestamp.to_s.empty?
+    raise "Could not get any timestamps from bzr!" if timestamp.blank?
     Time.parse(timestamp)
   end
 

Library/Homebrew/extend/os/linux/diagnostic.rb

@@ -35,7 +35,7 @@ module Homebrew
       end
 
       def check_xdg_data_dirs
-        return if ENV["XDG_DATA_DIRS"].to_s.empty?
+        return if ENV["XDG_DATA_DIRS"].blank?
         return if ENV["XDG_DATA_DIRS"].split("/").include?(HOMEBREW_PREFIX/"share")
         <<~EOS
           Homebrew's share was not found in your XDG_DATA_DIRS but you have

Library/Homebrew/global.rb

@@ -130,6 +130,7 @@ require "extend/pathname"
 require "extend/module"
 require "extend/predicable"
 require "extend/string"
+require "active_support/core_ext/object/blank"
 
 require "constants"
 require "exceptions"

Library/Homebrew/missing_formula.rb

@@ -142,8 +142,7 @@ module Homebrew
           hash, short_hash, *commit_message, relative_path =
             Utils.popen_read(log_command).gsub("\\n", "\n").lines.map(&:chomp)
 
-          if hash.to_s.empty? || short_hash.to_s.empty? ||
-             relative_path.to_s.empty?
+          if hash.blank? || short_hash.blank? || relative_path.blank?
             ofail "No previously deleted formula found." unless silent
             return
           end