Fix nested sessions' history saving

lib/irb.rb

@@ -482,9 +482,16 @@ def debug_break
     end
 
     def run(conf = IRB.conf)
+      in_nested_session = !!conf[:MAIN_CONTEXT]
       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?
+
+      if save_history
+        context.io.load_history
+      end
+
       prev_trap = trap("SIGINT") do
         signal_handle
       end
@@ -496,6 +503,7 @@ def run(conf = IRB.conf)
       ensure
         trap("SIGINT", prev_trap)
         conf[:AT_EXIT].each{|hook| hook.call}
+        context.io.save_history if save_history
       end
     end
 

lib/irb/context.rb

@@ -8,7 +8,6 @@
 require_relative "inspector"
 require_relative "input-method"
 require_relative "output-method"
-require_relative "history"
 
 module IRB
   # A class that wraps the current state of the irb session, including the
@@ -130,8 +129,6 @@ def initialize(irb, workspace = nil, input_method = nil)
       else
         @io = input_method
       end
-      self.save_history = IRB.conf[:SAVE_HISTORY] if IRB.conf[:SAVE_HISTORY]
-
       @extra_doc_dirs = IRB.conf[:EXTRA_DOC_DIRS]
 
       @echo = IRB.conf[:ECHO]
@@ -154,13 +151,6 @@ def initialize(irb, workspace = nil, input_method = nil)
 
     def save_history=(val)
       IRB.conf[:SAVE_HISTORY] = val
-
-      if val
-        context = (IRB.conf[:MAIN_CONTEXT] || self)
-        if context.io.support_history_saving? && !context.io.singleton_class.include?(HistorySavingAbility)
-          context.io.extend(HistorySavingAbility)
-        end
-      end
     end
 
     def save_history

lib/irb/history.rb

@@ -1,9 +1,7 @@
 module IRB
   module HistorySavingAbility # :nodoc:
-    def HistorySavingAbility.extended(obj)
-      IRB.conf[:AT_EXIT].push proc{obj.save_history}
-      obj.load_history
-      obj
+    def support_history_saving?
+      true
     end
 
     def load_history

lib/irb/input-method.rb

@@ -5,6 +5,7 @@
 #
 
 require_relative 'completion'
+require_relative "history"
 require 'io/console'
 require 'reline'
 
@@ -180,6 +181,8 @@ def self.initialize_readline
         include ::Readline
       end
 
+      include HistorySavingAbility
+
       # Creates a new input method object using Readline
       def initialize
         self.class.initialize_readline
@@ -233,10 +236,6 @@ def readable_after_eof?
         true
       end
 
-      def support_history_saving?
-        true
-      end
-
       # Returns the current line number for #io.
       #
       # #line counts the number of times #gets is called.
@@ -264,6 +263,7 @@ def inspect
 
   class RelineInputMethod < InputMethod
     HISTORY = Reline::HISTORY
+    include HistorySavingAbility
     # Creates a new input method object using Reline
     def initialize
       IRB.__send__(:set_encoding, Reline.encoding_system_needs.name, override: false)
@@ -466,10 +466,6 @@ def inspect
       str += " and #{inputrc_path}" if File.exist?(inputrc_path)
       str
     end
-
-    def support_history_saving?
-      true
-    end
   end
 
   class ReidlineInputMethod < RelineInputMethod

test/irb/test_history.rb

@@ -1,9 +1,12 @@
 # frozen_string_literal: false
 require 'irb'
 require 'readline'
+require "tempfile"
 
 require_relative "helper"
 
+return if RUBY_PLATFORM.match?(/solaris|mswin|mingw/i)
+
 module TestIRB
   class HistoryTest < TestCase
     def setup
@@ -205,4 +208,87 @@ def with_temp_stdio
       end
     end
   end
-end if not RUBY_PLATFORM.match?(/solaris|mswin|mingw/i)
+
+  class NestedIRBHistoryTest < IntegrationTestCase
+    def test_history_saving_with_nested_sessions
+      write_history ""
+
+      write_ruby <<~'RUBY'
+        def foo
+          binding.irb
+        end
+
+        binding.irb
+      RUBY
+
+      run_ruby_file do
+        type "'outer session'"
+        type "foo"
+        type "'inner session'"
+        type "exit"
+        type "'outer session again'"
+        type "exit"
+      end
+
+      assert_equal <<~HISTORY, @history_file.open.read
+        'outer session'
+        foo
+        'inner session'
+        exit
+        'outer session again'
+        exit
+      HISTORY
+    end
+
+    def test_history_saving_with_nested_sessions_and_prior_history
+      write_history <<~HISTORY
+        old_history_1
+        old_history_2
+        old_history_3
+      HISTORY
+
+      write_ruby <<~'RUBY'
+        def foo
+          binding.irb
+        end
+
+        binding.irb
+      RUBY
+
+      run_ruby_file do
+        type "'outer session'"
+        type "foo"
+        type "'inner session'"
+        type "exit"
+        type "'outer session again'"
+        type "exit"
+      end
+
+      assert_equal <<~HISTORY, @history_file.open.read
+        old_history_1
+        old_history_2
+        old_history_3
+        'outer session'
+        foo
+        'inner session'
+        exit
+        'outer session again'
+        exit
+      HISTORY
+    end
+
+    private
+
+    def write_history(history)
+      @history_file = Tempfile.new('irb_history')
+      @history_file.write(history)
+      @history_file.close
+      @irbrc = Tempfile.new('irbrc')
+      @irbrc.write <<~RUBY
+        IRB.conf[:HISTORY_FILE] = "#{@history_file.path}"
+      RUBY
+      @irbrc.close
+      @envs['IRBRC'] = @irbrc.path
+    end
+  end
+end