How do I test belongs_to associations with Rails 6 and RSpec 4.1?

Question

I’m upgrading from Rails 4.2 to 6. I'm also using FactoryBot 6.2.0. I have this model

class Book < ActiveRecord::Base
  belongs_to :author, inverse_of: :book
    …
  validates :model, presence: true, unless: -> { author.check_vwf? }

I have an RSpec (rspec-rails 4.1.2 ) test where I want to test an association …

describe Book do

    …
  it { should belong_to :author }

But running this test fails with the below error. It appears that the “validates” method is getting run and the instance being constructed has no “belongs_to” association, but that is exactly what I’m trying to test …

 Failure/Error: validates :model, presence: true, unless: -> { author.check_vwf? }
 
 NoMethodError:
   undefined method `check_vwf?' for nil:NilClass

Something about upgrading my Rails caused this test to suddenly fail. What’s the proper way with the given version of Rails and RSpec to test an association?

Please provide the code for the Books factory. Also, is there a book object created in the test? — Christos-Angelos Vasilopoulos, Dec 05 '21 at 20:45
THe "..." are just other "it" association checks. There is no explicit call to create an instance of the object. — Dave, Dec 05 '21 at 21:27
@Dave can you please update your question with both models. Seems something wrong there with association and `inverse_of` — Nitin Srivastava, Dec 06 '21 at 17:31
can you provide details on your factories and how you used them in the specs? have you used factory bot at all? — OuttaSpaceTime, Dec 13 '21 at 21:21

Christos-Angelos Vasilopoulos · Answer 1 · 2021-12-07T00:59:40.777

1

Shoulda matcher is defining a subject by default, but this subject creates a problem for your case. You could try adding the following at the start of the test file to override the default one.

let!(:author) { create(:author) }
subject { create(:book, author: author) }

Assuming you have defined the author and book factories.

edited Dec 07 '21 at 00:59

answered Dec 07 '21 at 00:37

Christos-Angelos Vasilopoulos

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Gave that a try but no dice. I don't think the "should belong_to" tests are using the subject I define. – Dave Dec 10 '21 at 17:36
what is your subject? – OuttaSpaceTime Dec 13 '21 at 21:21

score 1 · Answer 2 · edited Dec 17 '21 at 19:57

1

I think your issues could be related to your association. Since Rails 5 the belongs_to association is required by default.

If you want to be able to create records without the association you need to add the following:

 belongs_to :author, inverse_of: :book, optional: true

edited Dec 17 '21 at 19:57

Lori

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answered Dec 17 '21 at 00:52

Licke

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How do I test belongs_to associations with Rails 6 and RSpec 4.1?

2 Answers2