240220_database_cleaner_activerecord_multidb_spec.rb

#!/usr/bin/env ruby

def setcwd_to_tmpdir
  require "tmpdir"

  tmpdir = Dir.mktmpdir
  Dir.chdir(tmpdir)
end

def load_gems
  require "bundler/inline"

  gemfile(true) do
    source 'https://rubygems.org'
    gem 'rails', '~> 7.0.0'
    gem 'sqlite3', '~> 1'  # to avoid "can't activate sqlite3 (~> 1.4), already activated sqlite3-2.0.2-arm64-darwin."
    gem 'pry'
    gem 'rspec'
    gem 'database_cleaner-active_record', git: "https://github.com/DatabaseCleaner/database_cleaner-active_record.git", ref: "aafa5b2"
  end
end

def create_config_database_yml
  Dir.mkdir "config"
  IO.write("config/database.yml", <<~YAML)
    test:
      adapter: sqlite3
      database: "test.sqlite3"
    bar:
      adapter: sqlite3
      database: "bar.sqlite3"
  YAML
end

def setup_activerecord
  ActiveRecord::Base.configurations = YAML.load(IO.read("config/database.yml"))

  ActiveRecord::Base.logger = Logger.new(STDOUT)

  ActiveRecord::Base.establish_connection :test

  eval(<<~RUBY, TOPLEVEL_BINDING)
    class ApplicationRecord < ActiveRecord::Base
      primary_abstract_class
    end
  RUBY
end


setcwd_to_tmpdir
load_gems
create_config_database_yml
setup_activerecord

# defines Foo model, which use the connection pool from ApplicationRecord.
def define_foo_model
  eval(<<~RUBY, TOPLEVEL_BINDING)
    class Foo < ApplicationRecord
      connection.exec_query "CREATE TABLE foos (id INTEGER PRIMARY KEY)"
      reset_column_information
    end
  RUBY
end

# defines Bar model, which connects to alternate DB to be cleaned by DatabaseCleaner.
def define_bar_model
  eval(<<~RUBY, TOPLEVEL_BINDING)
    class Bar < ApplicationRecord
      establish_connection :bar
      connection.exec_query "CREATE TABLE bars (id INTEGER PRIMARY KEY)"
      reset_column_information
    end
  RUBY
end

RSpec.describe do
  it "works" do
    define_foo_model

    expect(Foo.connection.tables).to eq(["foos"])

    cleaner = DatabaseCleaner::Cleaners.new
    cleaner[:active_record, :db => :bar].strategy = :truncation
    cleaner.clean

    # define Bar model after `cleaner.clean`
    define_bar_model

    # Foo.connection gets replaced with Bar's connection!
    #
    # expected: ["foos"]
    #      got: ["bars"]
    expect(Foo.connection.tables).to eq(["foos"])
  end
end