Switching from :transaction to :truncation for some tests doesn't work

Bắt đầu trong spec/rails_helper.rb và tái hiện RSpec example được đánh dấu bằng truncate: true trong khi Sidekiq chạy như một process riêng biệt. Kiểm tra strategy của DatabaseCleaner sau hook và xác minh khả năng nhìn thấy các row từ PostgreSQL; hoàn tất khi các example được đánh dấu sử dụng truncation và expose các record ra bên ngoài, trong khi phần suite còn lại vẫn mang tính transactional.

So, I have some tests that need truncation because I am testing the whole Sidekiq stack and as a separate process Sidekiq needs to be able to see the records created in the original process. I want to keep the suite in general as :transaction though as the rest of the tests are fine with that strategy.

To do this I add come config to the rspec config:

config.before(:each) do |example|
  DatabaseCleaner.start

  if example.metadata[:truncate]
    DatabaseCleaner.strategy = :truncation
  else
    DatabaseCleaner.strategy = :transaction
  end
end

Then add metadata to the test:

it 'should doit', truncate: true do
  # create records then run the background worker
  # wait for the background worker to finish
end

The problem is that Sidekiq gets ActiveRecord not found errors, and sure enough, there are no rows available to on a separate database (postgres) connection:

connector_test=# select count(*) from contacts;
 count 
-------
     0
(1 row)

If I stick byebug in the test I can confirm that there are in fact records:

(byebug) Contact.count
3

but the strategey does seem to be truncation:

(byebug) DatabaseCleaner[:active_record].strategy.class
DatabaseCleaner::ActiveRecord::Truncation

(byebug) DatabaseCleaner[:active_record].strategy
#<DatabaseCleaner::ActiveRecord::Truncation:0x00007f95e600ff68 @only=nil, @tables_to_exclude=["schema_migrations"], @pre_count=nil, @reset_ids=nil, @cache_tables=true, @db=:default>

If I re-run the test after configuring truncation for all of the tests:

config.before(:suite) do
   DatabaseCleaner.strategy = :truncation
   …
end

I can see that the strategy in the test is the same:

(byebug) DatabaseCleaner[:active_record].strategy
#<DatabaseCleaner::ActiveRecord::Truncation:0x00007f8faf0ccec0 @only=nil, @tables_to_exclude=["schema_migrations"], @pre_count=nil, @reset_ids=nil, @cache_tables=true, @db=:default>

and the records are available in the test:

(byebug) Contact.count
3

but this time the records are also available in the database:

connector_test=# select count(*) from contacts;
 count 
-------
     3
(1 row)

and my test passes. These are the versions of relevant gems I am using

$ bundle info database_cleaner
  * database_cleaner (1.7.0)
	Summary: Strategies for cleaning databases.  Can be used to ensure a clean state for testing.
	Homepage: http://github.com/DatabaseCleaner/database_cleaner
	Path: /Users/will/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/database_cleaner-1.7.0

$ bundle info rspec-rails
  * rspec-rails (3.8.3)
	Summary: RSpec for Rails
	Homepage: https://github.com/rspec/rspec-rails
	Path: /Users/will/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rspec-rails-3.8.3

Upgrading database cleaner

So I noticed as I was gathering the version data that database_cleaner was out of date (I could have sworn that I updated it already!). Anyway, after upgrading database_cleaner it now looks like inside the test the reported strategy matches the observed behaviour:

(byebug) DatabaseCleaner[:active_record].strategy
#<DatabaseCleaner::ActiveRecord::Transaction:0x00007ff8ba938928 @db=:default>

This is despite my strategy switch seeming to work OK in the rspec config:

[57, 66] in /Users/will/clients/foo/repos/web-app/spec/rails_helper.rb
   57:   config.before(:each) do |example|
   58:     $redis.flushall
   59:     DatabaseCleaner.start
   60: 
   61:     byebug
=> 62:     if example.metadata[:truncate]
   63:       DatabaseCleaner.strategy = :truncation
   64:     else
   65:       DatabaseCleaner.strategy = :transaction
   66:     end
(byebug) example.metadata[:truncate]
true

and as the test is using transactions not truncation the external process can't see the records and the test fails. Any ideas what's going on here?