rails_issue_test.rb

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  gem "rails", "6.1.0"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :employees, force: true do |t|
    t.boolean :active, default: true
  end

  create_table :companies, force: true do |t|
    t.boolean :active, default: true
  end

  create_table :companies_assignments, force: true do |t|
    t.integer :employee_id
    t.integer :company_id
    t.string :position
  end
end

class Employee < ActiveRecord::Base
  # 1. Removing the where clause makes the problem go away, but I _always_ want it scoped like this.
  has_many :assignments,
           -> { where(companies: { active: true }) },
           class_name: "Companies::Assignment"

  has_many :companies, through: :assignments do
    # 2. Or I could remove the nested condition, but that's the whole point of this method.
    def with_position(position)
      where(active: true, companies_assignments: { position: position })
    end
  end
end

module Companies
  # 3. Or make the Assignment class not be in a module with a table_name_prefix, but that leads to
  #    ugly table names and naming clashes in my application.
  def self.table_name_prefix
    "companies_"
  end

  class Assignment < ActiveRecord::Base
    belongs_to :company
    belongs_to :employee
  end
end

class Company < ActiveRecord::Base
  has_many :assignments, class_name: "Companies::Assignment"
end

class BugTest < Minitest::Test
  def test_association_stuff
    employee = Employee.create!
    company = Company.create!

    Companies::Assignment.create!(employee: employee, company: company, position: "manager")
    Companies::Assignment.create!(employee: employee, company: company, position: "temp")

    assert_equal 2, employee.companies.count
    assert_equal 1, employee.companies.with_position("manager").count
  end
end