add after_initialize hooks

lib/iruby/kernel.rb

@@ -5,6 +5,18 @@ class Kernel
 
     class<< self
       attr_accessor :instance
+
+      def after_initialize_hooks
+        @after_initialize_hooks ||= []
+      end
+
+      def after_initialize(&block)
+        after_initialize_hooks << block
+      end
+
+      def run_after_initialize_hooks
+        after_initialize_hooks.each(&:call)
+      end
     end
 
     attr_reader :session
@@ -23,6 +35,8 @@ def initialize(config_file)
       @execution_count = 0
       @backend = create_backend
       @running = true
+
+      Kernel.run_after_initialize_hooks
     end
 
     def create_backend

test/iruby/kernel_test.rb

@@ -0,0 +1,29 @@
+require 'test_helper'
+require 'json'
+
+module IRubyTest
+  class KernelTest < TestBase
+    def test_after_intialize_hooks
+      ran_hook = false
+      IRuby::Kernel.after_initialize do
+        ran_hook = true
+      end
+
+      # may be better to put this in test/test_helper.rb
+      IRuby.logger ||= Logger.new(nil)
+
+      IRuby::Kernel.new(config_file.path)
+
+      assert ran_hook
+    ensure
+      IRuby::Kernel.after_initialize_hooks.clear
+    end
+
+    def config_file
+      config_file = Tempfile.new
+      config_file.write({key: ""}.to_json)
+      config_file.flush
+      config_file
+    end
+  end
+end