29498.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

gemfile(true) do
  source "https://rubygems.org"
  gem "rails", "5.0.3"
  gem "pg"
end

require "active_record"
require "minitest/autorun"
require "logger"

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

ActiveRecord::Schema.define do
  drop_table :things, if_exists: true
  create_table :things do |t|
    t.text :tags, array: true, default: []
    t.timestamps
  end

  drop_table :other_things, if_exists: true
  create_table :other_things do |t|
    t.text :tags, array: true, default: []
    t.timestamps
  end
end

class Thing < ActiveRecord::Base
  serialize(:tags, Array)
end

class OtherThing < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_pg_array_stuff_with_serialize
    thing = Thing.create(tags: ["a", "b", "c"])

    assert thing.persisted?
    assert_equal ["a", "b", "c"], thing.tags
  end

  def test_pg_array_stuff_without_serialize
    other_thing = OtherThing.create(tags: ["a", "b", "c"])
    assert other_thing.persisted?
    assert_equal ["a", "b", "c"], other_thing.tags
  end
end