testing models with builds or matcher in factory girl

Question

I have the following factory for patient_allergies

FactoryGirl.define do
  factory :patient_allergy do
    patient
    name 'Peanuts'
  end
end

The following factory for patient_allergy_reactions

FactoryGirl.define do
  factory :patient_allergy_reaction do
    patient_allergy
    name 'Fever'
    severity 'High'
  end
end

The model for patient_allergy looks like this:

class PatientAllergy < ActiveRecord::Base
  belongs_to :patient
  has_many :patient_allergy_reactions
end

the model for patient_allergy_reaction looks like this:

class PatientAllergyReaction < ActiveRecord::Base
  belongs_to :patient_allergy
end

My model tests look this:

it 'returns correct allergies with reactions' do
    #create an allergy
    allergy_name = 'Peanuts'
    patient_allergy = create(:patient_allergy, name: allergy_name, patient: patient)

    #create a allergy reaction
    reaction_name = 'Fever'
    reaction_severity = 'Low'
    allergy_reaction = create(:patient_allergy_reaction, name: reaction_name, severity: reaction_severity, patient_allergy: patient_allergy)

    expect(patient.patient_allergies.size).to eq(1)
    expect(patient.patient_allergies[0]).to eq(patient_allergy)
    expect(patient.patient_allergies[0].patient_allergy_reactions[0]).to eq(allergy_reaction)
  end

The above works fine but doesnt seem to add much value. I am trying to figure out a way to use build and traits for the above test. Else, is there a way to use the expect(patient).to have_many(:patient_allergies) matcher or something.

It would be really helpful if i could understand testing my models with factory girl.

Answer 1

The above works fine but doesnt seem to add much value

Agreed. Your model specs should test methods that you write, instead of testing the behavior of Rails.

If you want to test your associations, you can check out shoulda-matchers, which has standard tests for Rails models.