Scientist::Experiment.new creates Scientist::Default instance even when it should have been overridden

Author: mermopCreated Oct 19, 2018Updated Feb 28, 2023

Hi friends! Thank you for your great work with this gem :sparkles:

I am having a problem in Rails apps where Scientist::Experiment defaults to the original Default object until the custom one is called - leading to some head-scratching about why the try block is not running even when enabled? is set to true.

I'm unsure whether this is a problem with the Rails load order because of how I've arranged my files, whether the examples in the README could be a little better, or whether there's genuinely a bug here.

$ bundle exec rails console
Loading development environment (Rails 5.1.6)
irb(main):001:0> Scientist::Experiment.new "something"
=> #<Scientist::Default:0x00007fd667bbcd40 @name="something">
irb(main):002:0> LdapExperiment.new(name: "something")
=> #<LdapExperiment:0x00007fd667b6ee10 @name="something">
irb(main):003:0> Scientist::Experiment.new "something"
=> #<LdapExperiment:0x00007fd667b34968 @name="something">

I've followed the instructions in the README, which are delightful and comprehensive.

ruby

# app/experiments/ldap_experiment.rb
require "scientist/experiment"

class LdapExperiment
  include Scientist::Experiment

  attr_accessor :name

  def initialize(name:)
    @name = name
  end

  def enabled?
    # ...
  end

  def publish(result)
    # ...
  end
end

module Scientist::Experiment
  def self.new(name)
    LdapExperiment.new(name: name)
  end
end

ruby

# app/models/whatever.rb
class Whatever
  include Scientist
  def do_something
    science "role lookup" do |e|
      e.use { do_one_thing }
      e.try { do_some_other_thing }
    end
  end
end

This is occurring in Rails 3.2.x and Rails 5.1.x applications, with version 1.2.0 of the gem.

Source: github/scientist

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