Parser: Add env named argument for switch to check environment variables

Library/Homebrew/cli_parser.rb

@@ -10,13 +10,12 @@ module Homebrew
         instance_eval(&block)
       end
 
-      def switch(*names, description: nil)
+      def switch(*names, description: nil, env: nil)
         description = option_to_description(*names) if description.nil?
         @parser.on(*names, description) do
-          names.each do |name|
-            @parsed_args["#{option_to_name(name)}?"] = true
-          end
+          enable_switch(*names)
         end
+        enable_switch(*names) if !env.nil? && !ENV["HOMEBREW_#{env.to_s.upcase}"].nil?
       end
 
       def comma_array(name, description: nil)
@@ -50,6 +49,14 @@ module Homebrew
         @parser.parse!(cmdline_args)
         @parsed_args
       end
+
+      private
+
+      def enable_switch(*names)
+        names.each do |name|
+          @parsed_args["#{option_to_name(name)}?"] = true
+        end
+      end
     end
   end
 end

Library/Homebrew/dev-cmd/irb.rb

@@ -6,7 +6,6 @@
 #:    used instead of irb.
 
 require "cli_parser"
-require "utils/env"
 
 class Symbol
   def f(*args)
@@ -26,7 +25,7 @@ module Homebrew
   def irb
     args = Homebrew::CLI::Parser.new do
       switch "--examples"
-      switch "--pry"
+      switch "--pry", env: :pry
     end.parse
 
     if args.examples?
@@ -37,7 +36,7 @@ module Homebrew
       return
     end
 
-    if args.pry? || Utils::EnvVars.pry?
+    if args.pry?
       Homebrew.install_gem_setup_path! "pry"
       require "pry"
       Pry.config.prompt_name = "brew"
@@ -53,7 +52,7 @@ module Homebrew
 
     ohai "Interactive Homebrew Shell"
     puts "Example commands available with: brew irb --examples"
-    if args.pry? || Utils::EnvVars.pry?
+    if args.pry?
       Pry.start
     else
       IRB.start

Library/Homebrew/test/cli_parser_spec.rb

@@ -6,6 +6,7 @@ describe Homebrew::CLI::Parser do
       described_class.new do
         switch "-v", "--verbose", description: "Flag for verbosity"
         switch "--more-verbose",  description: "Flag for higher verbosity"
+        switch "--pry", env: :pry
       end
     }
 
@@ -34,6 +35,12 @@ describe Homebrew::CLI::Parser do
     it "raises an exception when an invalid option is passed" do
       expect { parser.parse(["--random"]) }.to raise_error(OptionParser::InvalidOption, /--random/)
     end
+
+    it "maps environment var to an option" do
+      allow(ENV).to receive(:[]).with("HOMEBREW_PRY").and_return("1")
+      args = parser.parse([])
+      expect(args.pry?).to be true
+    end
   end
 
   describe "test long flag options" do

Library/Homebrew/utils/env.rb

@@ -1,9 +0,0 @@
-module Utils
-  module EnvVars
-    class << self
-      def pry?
-        !ENV["HOMEBREW_PRY"].nil?
-      end
-    end
-  end
-end