IN YOUR ActiveRecord::Face

face.rb

# DISCLAIMER: Beer was consumed

# Need to make assertions about ActiveRecord query messages applied to
# a model but don't want to include AR as a dependency? Feeling yolo?

# I had that situation lately with a gem that takes params and uses macros
# to build a scoped relation (github.com/hooroo/query_ar), so I cooked this up.

# Usage is as follows.

# Declare a class that inherits us instead of AR::Base
#
#   class User < ActiveRecord::Face
#     scope :active
#   end

# Chain a bunch of query methods together
#
#   > User.active.where(name: 'stu').order('name').limit(10).offset(0)

# Find out what messages where received and with what args, useful for assertions
#
#   > User.messages_received
#   => {:active=>[], :where=>[{:name=>"stu"}], :order=>["name"], :limit=>[10], :offset=>[0]}

require 'active_support/core_ext'

module ActiveRecord
  class Face

    class_attribute :messages_received, :expected_messages

    self.expected_messages = Set.new([
      :all,
      :where,
      :order,
      :limit,
      :offset,
      :includes
    ])

    def self.scope(name)
      self.expected_messages << name.to_sym
    end

    def self.method_missing(method, *args, &block)
      super unless self.expected_messages.include?(method)

      self.messages_received ||= {}
      self.messages_received.merge!(method => args)
      self
    end

  end
end

face_spec.rb

require 'support/active_record/face'

class FakeModel < ActiveRecord::Face
  scope :active
end

describe ActiveRecord::Face do

  it "keeps track of class messages received" do
    FakeModel.active.where(name: 'stu').order('name').limit(10).offset(0)
    messages = FakeModel.messages_received
    expect(messages.keys.length).to eq 5
    expect(messages).to include(active: [])
    expect(messages).to include(where:  [{name: 'stu'}])
    expect(messages).to include(order:  ['name'])
    expect(messages).to include(limit:  [10])
    expect(messages).to include(offset: [0])
  end

end