14493.rb

require 'active_record'
require 'minitest/autorun'
require 'logger'

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: 'sqlite3', database: ':memory:')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :posts do |t|
    t.string  :name
    t.integer :some_counter
  end
end

class Post < ActiveRecord::Base

  after_commit :do_something, on: :create
  
  def do_something
    logger.debug 'do_something'
    increment!(:some_counter)
  end
end

class BugTest < Minitest::Test
  def test_after_commit_with_on_create
    post = Post.create!
    assert_equal 1, post.some_counter
  end
  
  def test_after_commit_with_on_create_not_triggered_on_update
    post = Post.create!
    assert_equal 1, post.some_counter
    
    post.name = 'Bob'
    post.save
    post.reload
    
    assert_equal 1, post.some_counter
  end
end