ActiveRecord Timestamp Precision Bug Report

gistfile1.rb

unless File.exist?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', github: 'rails/rails'
    gem 'arel', github: 'rails/arel'
    gem 'mysql2', '0.3.18'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

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

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: 'mysql2', database: 'test42', username: 'test42', password: 'test42', host: 'localhost')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :foos, force: true  do |t|
    t.timestamps
  end
end

class Foo < ActiveRecord::Base; end

class BugTest < Minitest::Test
  def test_timestamp_precision
    time_now = Time.now
    timestamp_pattern = /`foos`.`created_at` = '(.*)'/

    query_time_with_hash = Foo.where(created_at: time_now).to_sql.match(timestamp_pattern)[1]
    query_time_with_string = Foo.where('`foos`.`created_at` = ?', time_now).to_sql.match(timestamp_pattern)[1]

    assert_equal query_time_with_string, query_time_with_hash
  end
end

# Output:
#  1) Failure:
#BugTest#test_timestamp_precision [./active_record_master.rb:39]:
#Expected: "2015-05-18 17:53:04.907246"
#  Actual: "2015-05-18 17:53:04"