Support activating IRB as console with a config

README.md

@@ -477,6 +477,7 @@ config set no_color true
   * `RUBY_DEBUG_NO_RELINE` (`no_reline`): Do not use Reline library (default: false)
   * `RUBY_DEBUG_NO_HINT` (`no_hint`): Do not show the hint on the REPL (default: false)
   * `RUBY_DEBUG_NO_LINENO` (`no_lineno`): Do not show line numbers (default: false)
+  * `RUBY_DEBUG_IRB_CONSOLE` (`irb_console`): Use IRB as the console (default: false)
 
 * CONTROL
   * `RUBY_DEBUG_SKIP_PATH` (`skip_path`): Skip showing/entering frames for given paths

lib/debug/config.rb

@@ -22,6 +22,7 @@ module DEBUGGER__
     no_reline:      ['RUBY_DEBUG_NO_RELINE',      "UI: Do not use Reline library",              :bool, "false"],
     no_hint:        ['RUBY_DEBUG_NO_HINT',        "UI: Do not show the hint on the REPL",       :bool, "false"],
     no_lineno:      ['RUBY_DEBUG_NO_LINENO',      "UI: Do not show line numbers",               :bool, "false"],
+    irb_console:    ["RUBY_DEBUG_IRB_CONSOLE",    "UI: Use IRB as the console",                 :bool, "false"],
 
     # control setting
     skip_path:      ['RUBY_DEBUG_SKIP_PATH',      "CONTROL: Skip showing/entering frames for given paths", :path],

lib/debug/session.rb

@@ -202,6 +202,11 @@ def activate ui = nil, on_fork: false
         end
         @tp_thread_end.enable
 
+        if CONFIG[:irb_console] && !CONFIG[:open]
+          require_relative "irb_integration"
+          thc.activate_irb_integration
+        end
+
         # session start
         q << true
         session_server_main

test/console/irb_test.rb

@@ -24,5 +24,22 @@ def test_irb_command_switches_console_to_irb
         type 'q!'
       end
     end
+
+    def test_irb_console_config_activates_irb
+      ENV["RUBY_DEBUG_IRB_CONSOLE"] = "true"
+
+      debug_code(program, remote: false) do
+        type '123'
+        assert_line_text 'irb:rdbg(main):002> 123'
+        type 'irb_info'
+        assert_line_text('IRB version:')
+        type 'next'
+        type 'info'
+        assert_line_text([/a = 1/, /b = nil/])
+        type 'q!'
+      end
+    ensure
+      ENV["RUBY_DEBUG_IRB_CONSOLE"] = nil
+    end
   end
 end