[ruby/irb] Support VISUAL env var, and prefer it over EDITOR

(https://github.com/ruby/irb/pull/686)

* Support `VISUAL` env var, and prefer it over `EDITOR`

* Update test/irb/test_cmd.rb

---------

https://github.com/ruby/irb/commit/399b872c31

Co-authored-by: Stan Lo <stan001212@gmail.com>

lib/irb/cmd/edit.rb

@@ -8,7 +8,7 @@ module IRB
   module ExtendCommand
     class Edit < Nop
       category "Misc"
-      description 'Open a file with the editor command defined with `ENV["EDITOR"]`.'
+      description 'Open a file with the editor command defined with `ENV["VISUAL"]` or `ENV["EDITOR"]`.'
 
       class << self
         def transform_args(args)
@@ -45,12 +45,12 @@ module IRB
           end
         end
 
-        if editor = ENV['EDITOR']
+        if editor = (ENV['VISUAL'] || ENV['EDITOR'])
           puts "command: '#{editor}'"
           puts "   path: #{path}"
           system(*Shellwords.split(editor), path)
         else
-          puts "Can not find editor setting: ENV['EDITOR']"
+          puts "Can not find editor setting: ENV['VISUAL'] or ENV['EDITOR']"
         end
       end
     end

test/irb/test_cmd.rb

@@ -920,12 +920,15 @@ module TestIRB
 
   class EditTest < CommandTestCase
     def setup
+      @original_visual = ENV["VISUAL"]
       @original_editor = ENV["EDITOR"]
       # noop the command so nothing gets executed
-      ENV["EDITOR"] = ": code"
+      ENV["VISUAL"] = ": code"
+      ENV["EDITOR"] = ": code2"
     end
 
     def teardown
+      ENV["VISUAL"] = @original_visual
       ENV["EDITOR"] = @original_editor
     end
 
@@ -988,5 +991,18 @@ module TestIRB
       assert_match(/path: .*\/lib\/irb\.rb/, out)
       assert_match("command: ': code'", out)
     end
+
+    def test_edit_with_editor_env_var
+      ENV.delete("VISUAL")
+
+      out, err = execute_lines(
+        "edit",
+        irb_path: __FILE__
+      )
+
+      assert_empty err
+      assert_match("path: #{__FILE__}", out)
+      assert_match("command: ': code2'", out)
+    end
   end
 end