Fail to setup database_cleaner for dual database

[leomao10]

I have two database, one with a model call Device, and the other has a model call User.

When I set up database_cleaner according to readme describe:

  config.use_transactional_fixtures = false
  config.before(:suite) do
    DatabaseCleaner[:active_record,{:connection => :test}].strategy  = :transaction
    DatabaseCleaner[:active_record,{:connection => :secondary_test}].strategy = :transaction
  end

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end

I found that in my test, device model's connection will point to secondary_test database. And I will have following error as my secondary_test database don't have a table call devices:

ActiveRecord::StatementInvalid:
  PG::UndefinedTable: ERROR:  relation "devices" does not exist
  LINE 5:                WHERE a.attrelid = '"devices"'::regclass
                                            ^
  :               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                       pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                  FROM pg_attribute a LEFT JOIN pg_attrdef d
                    ON a.attrelid = d.adrelid AND a.attnum = d.adnum
                 WHERE a.attrelid = '"devices"'::regclass
                   AND a.attnum > 0 AND NOT a.attisdropped
                 ORDER BY a.attnum

I dig in the code, and found that it is cause by #connection_class

      def connection_class
        @connection_class ||= if db && !db.is_a?(Symbol)
                                db
                              elsif connection_hash
                                lookup_from_connection_pool || establish_connection
                              else
                                ::ActiveRecord::Base
                              end
      end

      private

      def lookup_from_connection_pool
        if ::ActiveRecord::Base.respond_to?(:descendants)
          database_name = connection_hash["database"] || connection_hash[:database]
          models        = ::ActiveRecord::Base.descendants
          models.detect { |m| m.connection_pool.spec.config[:database] == database_name }
        end
      end

      def establish_connection
        ::ActiveRecord::Base.establish_connection(connection_hash)
      end

However, since ::ActiveRecord::Base.descendants is blank when lookup_from_connection_pool is called, lookup_from_connection_pool would return nil, and establish_connection will be called. Unfortunately, ActiveRecord::Base.establish_connection(connection_hash) has a huge side effect in Rails 4+. It will set connection to specify one for ALL models that inherit from ActiveRecord::Base class. This can be reproduced by following code:

ActiveRecord::Base.establish_connection('test')
Device.connection

In my case, following code:

DatabaseCleaner[:active_record,{:connection => :test}].start
DatabaseCleaner[:active_record,{:connection => :secondary_test}].start

will first set ALL ActiveRecord::Base descendants' connections to test db, then it will set ALL their connection to secondary_test. Therefore, when I try to use Device in my spec, I will have PG::UndefinedTable: ERROR

Here is the similar issues that cause by the side effect for establish_connection:

• Strange rails4 + establish_connection issue #245

[etagwerker]

@leomao10 Could you try this workaround and report back? https://gist.github.com/mgreenly/1109325

Thanks!

[fmnoise]

I've fixed this by adding Rails.application.eager_load! to spec helper

RSpec.configure do |config|
  config.use_transactional_fixtures = false

  Rails.application.eager_load!

  %i(db_test1 db_test2 db_test3).each do |connection|
    config.before :suite do
      # transaction strategy is not working with multiple databases
      DatabaseCleaner[:active_record, { connection: connection }].strategy = :deletion
      DatabaseCleaner[:active_record, { connection: connection }].clean_with :truncation
    end

    config.around :each do |example|
      DatabaseCleaner[:active_record, { connection: connection }].cleaning &example
    end
  end
end