[ruby/irb] Polish the exit! command and its tests

(https://github.com/ruby/irb/pull/867)

* Remove IRB.irb_exit! method

It's not necessary to introduce a new method just for the exit! command
at this moment.

* Rename ExitForcedAction to ForceExit

* Move force exit tests to a dedicated file

* Fix nested history saving with exit! command

Because we switched to use `Kernel#exit` instead of `exit!`, the outer
session's ensure block in `Irb#run` will be run, which will save the
history. This means the separate check to save history when force exiting
is no longer necessary.

* execute_lines helper should also capture IRB setup's output

This prevents setup warnings from being printed to test output
while allowing those output to be tested.

* Update readme

https://github.com/ruby/irb/commit/899d10ade1

3 files changed, 6 insertions, 15 deletions

diff --git a/lib/irb.rb b/lib/irb.rb
index ad6ec78aa4..3830867e6a 100644
--- a/lib/irb.rb
+++ b/lib/irb.rb
@@ -889,10 +889,6 @@ module IRB
     throw :IRB_EXIT, false
   end
 
-  def IRB.irb_exit!(*)
-    throw :IRB_EXIT, true
-  end
-
   # Aborts then interrupts irb.
   #
   # Will raise an Abort exception, or the given +exception+.
@@ -972,8 +968,7 @@ module IRB
       conf[:IRB_RC].call(context) if conf[:IRB_RC]
       conf[:MAIN_CONTEXT] = context
 
-      supports_history_saving = conf[:SAVE_HISTORY] && context.io.support_history_saving?
-      save_history = !in_nested_session && supports_history_saving
+      save_history = !in_nested_session && conf[:SAVE_HISTORY] && context.io.support_history_saving?
 
       if save_history
         context.io.load_history
@@ -993,12 +988,8 @@ module IRB
         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
+        context.io.save_history if save_history
+        Kernel.exit(0) if forced_exit
       end
     end
 
diff --git a/lib/irb/cmd/exit_forced_action.rb b/lib/irb/cmd/force_exit.rb
index e5df75b682..2b9f296865 100644
--- a/lib/irb/cmd/exit_forced_action.rb
+++ b/lib/irb/cmd/force_exit.rb
@@ -6,12 +6,12 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class ExitForcedAction < Nop
+    class ForceExit < Nop
       category "IRB"
       description "Exit the current process."
 
       def execute(*)
-        IRB.irb_exit!
+        throw :IRB_EXIT, true
       rescue UncaughtThrowError
         Kernel.exit(0)
       end
diff --git a/lib/irb/extend-command.rb b/lib/irb/extend-command.rb
index 2db2b80578..d303bf76da 100644
--- a/lib/irb/extend-command.rb
+++ b/lib/irb/extend-command.rb
@@ -37,7 +37,7 @@ module IRB # :nodoc:
         [:irb_quit, OVERRIDE_PRIVATE_ONLY],
       ],
       [
-        :irb_exit!, :ExitForcedAction, "cmd/exit_forced_action",
+        :irb_exit!, :ForceExit, "cmd/force_exit",
         [:exit!, OVERRIDE_PRIVATE_ONLY],
       ],