How to test model's callback method independently?

Question

I had a method in a model:

class Article < ActiveRecord::Base
  def do_something
  end
end

I also had a unit test for this method:

Answer 1

I like to use ActiveRecord #run_callbacks method to make sure callbacks are been called without need to hit database. This way it runs faster.

describe "#save" do
  let(:article) { FactoryBot.build(:article) }
  it "runs .do_something after save" do
    expect(article).to receive(:do_something)
    article.run_callbacks(:save)
  end
end

And to test the behavior of #do_something you add another test specifically for that.

describe "#do_something" do
  let(:article) { FactoryBot.build(:article) }
  it "return thing" do
    expect(article.do_something).to be_eq("thing")
  end
end