Testing service object

user_creator_spec.rb

describe UserCreator do
  describe "#create_user" do
    it "creates user" do
      user_creator = UserCreator.new("ian@brown.com", "Ian", "Brown")
      user_creator.create_user

      expect(user_creator.created_user.email).to      eq("ian@brown.com")
      expect(user_creator.created_user.first_name).to eq("Ian")
      expect(user_creator.created_user.last_name).to  eq("Brown")
    end

    context "no email given" do
      it "raises exception" do
        expect {
          UserCreator.new(nil, "Ian", "Brown")
        }.to raise_error(/Missing email/)
      end
    end

    context "user already exists" do
      ...
    end
  end
end