https://github.com/influitive/apartment/issues/264#issuecomment-146222681

thread_spec.rb

require 'spec_helper'

describe 'thread safe tenants' do
  let(:db_names) { [db1, db2] }

  before do
    Apartment.configure do |config|
      config.excluded_models = ["Company"]
      config.tenant_names = lambda{ Company.pluck(:database) }
      config.use_schemas = false
    end

    Apartment::Tenant.reload!(config)

    db_names.each do |db_name|
      Apartment::Tenant.create(db_name)
      Company.create database: db_name
    end
  end

  after do
    db_names.each{ |db| Apartment::Tenant.drop(db) }
    Apartment::Tenant.reset
    Company.delete_all
  end

  def get_thread(tenant)
    Thread.new do
      Apartment::Tenant.switch(tenant) do
        (0..5).each do |i|
          sleep 1
          expect(tenant).to eq Apartment::Tenant.current
        end
      end
    end
  end

  it 'ensures each thread keeps the desired tenant' do
    t1 = get_thread(db1)
    sleep(1)
    t2 = get_thread(db2)
    t1.join
    t2.join
  end
end