[ruby/irb] Introduce exit! command

(https://github.com/ruby/irb/pull/851)

* Added failing test for when writing history on exit

* Save history on exit

* Exit early when calling Kernel.exit

* use status 0 for kernel.exit

* Added test for nested sessions

* Update lib/irb.rb

---------

https://github.com/ruby/irb/commit/c0a5f31679

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

lib/irb.rb

@@ -886,7 +886,11 @@ module IRB
 
   # Quits irb
   def IRB.irb_exit(*)
-    throw :IRB_EXIT
+    throw :IRB_EXIT, false
+  end
+
+  def IRB.irb_exit!(*)
+    throw :IRB_EXIT, true
   end
 
   # Aborts then interrupts irb.
@@ -968,7 +972,8 @@ module IRB
       conf[:IRB_RC].call(context) if conf[:IRB_RC]
       conf[:MAIN_CONTEXT] = context
 
-      save_history = !in_nested_session && conf[:SAVE_HISTORY] && context.io.support_history_saving?
+      supports_history_saving = conf[:SAVE_HISTORY] && context.io.support_history_saving?
+      save_history = !in_nested_session && supports_history_saving
 
       if save_history
         context.io.load_history
@@ -979,15 +984,23 @@ module IRB
       end
 
       begin
-        catch(:IRB_EXIT) do
+        forced_exit = false
+
+        forced_exit = catch(:IRB_EXIT) do
           eval_input
         end
       ensure
         trap("SIGINT", prev_trap)
         conf[:AT_EXIT].each{|hook| hook.call}
+
+        if forced_exit
+          context.io.save_history if supports_history_saving
+          Kernel.exit(0)
+        else
           context.io.save_history if save_history
         end
       end
+    end
 
     # Evaluates input for this session.
     def eval_input

lib/irb/cmd/exit_forced_action.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require_relative "nop"
+
+module IRB
+  # :stopdoc:
+
+  module ExtendCommand
+    class ExitForcedAction < Nop
+      category "IRB"
+      description "Exit the current process."
+
+      def execute(*)
+        IRB.irb_exit!
+      rescue UncaughtThrowError
+        Kernel.exit(0)
+      end
+    end
+  end
+
+  # :startdoc:
+end

lib/irb/extend-command.rb

@@ -36,6 +36,11 @@ module IRB # :nodoc:
         [:quit, OVERRIDE_PRIVATE_ONLY],
         [:irb_quit, OVERRIDE_PRIVATE_ONLY],
       ],
+      [
+        :irb_exit!, :ExitForcedAction, "cmd/exit_forced_action",
+        [:exit!, OVERRIDE_PRIVATE_ONLY],
+      ],
+
       [
         :irb_current_working_workspace, :CurrentWorkingWorkspace, "cmd/chws",
         [:cwws, NO_OVERRIDE],

test/irb/test_debug_cmd.rb

@@ -255,6 +255,47 @@ module TestIRB
       assert_match(/irb\(main\):001> next/, output)
     end
 
+    def test_forced_exit_finishes_process_when_nested_sessions
+      write_ruby <<~'ruby'
+        puts "First line"
+        puts "Second line"
+        binding.irb
+        puts "Third line"
+        binding.irb
+        puts "Fourth line"
+      ruby
+
+      output = run_ruby_file do
+        type "123"
+        type "456"
+        type "exit!"
+      end
+
+      assert_match(/First line\r\n/, output)
+      assert_match(/Second line\r\n/, output)
+      assert_match(/irb\(main\):001> 123/, output)
+      assert_match(/irb\(main\):002> 456/, output)
+      refute_match(/Third line\r\n/, output)
+      refute_match(/Fourth line\r\n/, output)
+    end
+
+    def test_forced_exit
+      write_ruby <<~'ruby'
+        puts "Hello"
+        binding.irb
+      ruby
+
+      output = run_ruby_file do
+        type "123"
+        type "456"
+        type "exit!"
+      end
+
+      assert_match(/Hello\r\n/, output)
+      assert_match(/irb\(main\):001> 123/, output)
+      assert_match(/irb\(main\):002> 456/, output)
+    end
+
     def test_quit
       write_ruby <<~'RUBY'
         binding.irb

test/irb/test_history.rb

@@ -379,6 +379,24 @@ module TestIRB
       HISTORY
     end
 
+    def test_history_saving_with_exit!
+      write_history ""
+
+      write_ruby <<~'RUBY'
+        binding.irb
+      RUBY
+
+      run_ruby_file do
+        type "'starting session'"
+        type "exit!"
+      end
+
+      assert_equal <<~HISTORY, @history_file.open.read
+        'starting session'
+        exit!
+      HISTORY
+    end
+
     def test_history_saving_with_nested_sessions_and_prior_history
       write_history <<~HISTORY
         old_history_1