[ruby/irb] Add whereami command

https://github.com/ruby/irb/commit/bc822e4aac

lib/irb/cmd/whereami.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require_relative "nop"
+
+# :stopdoc:
+module IRB
+  module ExtendCommand
+    class Whereami < Nop
+      def execute(*)
+        code = irb_context.workspace.code_around_binding
+        if code
+          puts code
+        else
+          puts "The current context doesn't have code."
+        end
+      end
+    end
+  end
+end
+# :startdoc:

lib/irb/extend-command.rb

@@ -135,6 +135,11 @@ module IRB # :nodoc:
         [:measure, NO_OVERRIDE],
       ],
 
+      [
+        :irb_whereami, :Whereami, "irb/cmd/whereami",
+        [:whereami, NO_OVERRIDE],
+      ],
+
     ]
 
     # Installs the default irb commands:

test/irb/test_cmd.rb

@@ -391,5 +391,22 @@ module TestIRB
       assert_empty err
       assert_match(/^instance variables: @a\n/, out)
     end
+
+    def test_whereami
+      IRB.init_config(nil)
+      workspace = IRB::WorkSpace.new(self)
+      irb = IRB::Irb.new(workspace)
+      IRB.conf[:MAIN_CONTEXT] = irb.context
+      input = TestInputMethod.new([
+        "whereami\n",
+      ])
+      irb = IRB::Irb.new(IRB::WorkSpace.new(Object.new), input)
+      irb.context.return_format = "=> %s\n"
+      out, err = capture_output do
+        irb.eval_input
+      end
+      assert_empty err
+      assert_match(/^From: .+ @ line \d+ :\n/, out)
+    end
   end
 end