Test parallelization using Config.connect_to

[asgerb]

I've implemented test parallelization in my app using this module to "fork" the database, following the example found in ActiveRecord:

require "active_support/testing/parallelization"
module Mongoid
  module TestDatabases # :nodoc:
    ActiveSupport::Testing::Parallelization.after_fork_hook do |i|
      Mongoid::Config.connect_to("#{database_name}-#{i}")
    end

    def self.database_name
      Mongoid::Config.clients["default"]["database"]
    end
  end
end

This worked fine so far, but I've been running into issues lately as I'm transitioning to running tests in containers.
Specifically the test suite would try to connect to localhost:27017 no matter what values I would configure in mongoid.yml. After some debugging I found out that issue stems from my use of Mongoid::Config.connect_to, which changes the hosts to localhost:27017.

It would be great to make it either possible to pass in the hosts, or possibly to read the hosts from the config if possible? We could then fall back to localhost:27017 if that fails. Would be open to make a PR following any guidance on which path to take.

For anyone stumbling on this looking for a solution, here's my dirty hack to make it work:

require "active_support/testing/parallelization"
module Mongoid
  module TestDatabases # :nodoc:
    ActiveSupport::Testing::Parallelization.after_fork_hook do |i|
      Mongoid::Config.send("clients=", {
        default: {
          database: "#{database_name}-#{i}",
          hosts: database_hosts,
          options: { read: { mode: :primary }}
        }
      })
    end

    def self.database_name
      Mongoid::Config.clients["default"]["database"]
    end

    def self.database_hosts
      Mongoid::Config.clients["default"]["hosts"]
    end
  end
end

[p-mongo]

Hi @asgerb ,

Programmatic configuration of Mongoid is described in https://www.mongodb.com/docs/mongoid/master/reference/configuration/#loading-mongoid-configuration (Mongoid.configure etc.). Does this answer your question?