Rails and Rspec Unit Testing Static Methods

Question

I have a very simple static method in one of my models:

def self.default
    self.find(1)
end

I'm trying to write a simple Rspec unit test for it that doesn't make any calls to the DB. How do I write a test that generates a few sample instances for the test to return? Feel free to complete this:

describe ".default" do
    context "when testing the default static method" do
        it "should return the instance where id = 1" do

        end
    end
end

The model file is as follows:

  class Station < ApplicationRecord
  acts_as_paranoid
  acts_as_list
  nilify_blanks

  belongs_to :color
  has_many :jobs
  has_many :station_stops
  has_many :logs, -> { where(applicable_class: :Station) }, foreign_key: :applicable_id
  has_many :chattels, -> { where(applicable_class: :Station) }, foreign_key: :applicable_id

  delegate :name, :hex, to: :color, prefix: true

  def name
    "#{full_display} Station"
  end

  def small_display
    display_short || code.try(:titleize)
  end

  def full_display
    display_long || small_display
  end

  def average_time
    Time.at(station_stops.closed.average(:time_lapsed)).utc.strftime("%-M:%S")
  end

  def self.default
    # referencing migrate/create_stations.rb default for jobs
    self.find(1)
  end

  def self.first
    self.where(code: Constant.get('station_code_to_enter_lab')).first
  end
end

The spec file is as follows:

require "rails_helper"
describe Station do

  subject { described_class.new  }

  describe "#name" do
    context "when testing the name method" do
      it "should return the capitalized code with spaces followed by 'Station'" do
        newStation = Station.new(code: 'back_to_school')
        result = newStation.name
        expect(result).to eq 'Back To School Station'
      end
    end
  end

  describe "#small_display" do
    context "when testing the small_display method" do
      it "should return the capitalized code with spaces" do
        newStation = Station.new(code: 'back_to_school')
        result = newStation.small_display
        expect(result).to eq 'Back To School'
      end
    end
  end

  describe "#full_display" do
    context "when testing the full_display method" do
      it "should return the capitalized code with spaces" do
        newStation = Station.new(code: 'back_to_school')
        result = newStation.full_display
        expect(result).to eq 'Back To School'
      end
    end
  end

  describe ".default" do
    context "" do
      it "" do

      end
    end
  end

end

Answer 1

You can use stubbing to get you there

describe ".default" do
    context "when testing the default static method" do
        let(:dummy_station) { Station.new(id: 1) }
        before { allow(Station).to receive(:default).and_return(dummy_station)

        it "should return the instance where id = 1" do
          expect(Station.default.id).to eq 1
        end
    end
end