Should I stub the model in Factory girl or in the spec file while testing?

Question

Almost every spec file I come accross I end up writing stuff like:

  before :each do
    @cimg = Factory.build :cimg_valid
    @cimg.stub(:validate_img).and_return true
    @cimg.stub(:validate_img_url).and_return true
    @cimg.stub(:save_images).and_return true
    @cimg.stub(:process_image).and_return true
    @cimg.stub(:img).and_return true
  end

I mean, the model I get from Factory.build is completely valid. But if I don't stub that stuff it saves things in the filesystem, and validates stuff I'm not testing...

What I mean, I think it would be cleaner to do something like this:

  before :each do
    @cimg = Factory.build :cimg_for_testing_tags
  end

If stubbing within the Factory is even possible.

What is the proper way to stub the model?

score 35 · Answer 1 · edited Sep 05 '19 at 16:50

35

@fkreusch's answer works great until you use the new RSpec expect() syntax (3.0+)

Putting this into rails_helper.rb works for me:

FactoryBot::SyntaxRunner.class_eval do
  include RSpec::Mocks::ExampleMethods
end

In the OP's example, you can now do:

FactoryBot.define do
  factory :cimg_for_testing_tags do

    ... # Factory attributes

    after(:build) do |cimg|
      allow(cimg).to receive(:validate_img) { true }
    end
  end
end

Credit: github.com/printercu, see: https://github.com/thoughtbot/factory_bot/issues/703#issuecomment-83960003

edited Sep 05 '19 at 16:50

Qortex

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answered Jun 30 '15 at 04:16

Ho-Sheng Hsiao

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5

Doing what is described here now issues the following error (FactoryGirl v4.7.0): ```The use of doubles or partial doubles from rspec-mocks outside of the per-test lifecycle is not supported. ``` – jsears Sep 29 '16 at 17:20
@jsears I was encountering that error because my `rails_helper.rb` was running `FactoryGirl.lint` in a `before(:suite)` block, and stubs can't be set up there. I solved the issue by wrapping the lint call in `RSpec::Mocks.with_temporary_scope { ... }`. – vergenzt Nov 28 '16 at 22:22
1

Note that `FactoryGirl` is now `FactoryBot`, so those two names should change in your example. – aardvarkk Dec 14 '17 at 00:00

score 22 · Accepted Answer · edited Aug 07 '14 at 02:46

22

In recent versions of factory_girl you have an after_build callback, so I believe you could define your factory like this:

FactoryGirl.define do
  factory :cimg_for_testing_tags do

    ... # Factory attributes

    after_build do |cimg|
      cimg.stub(:validate_img).and_return true
    end
  end
end

UPDATE

After factory_girl 3.3.0, the syntax has changed to following:

FactoryGirl.define do
  factory :cimg_for_testing_tags do

    ... # Factory attributes

    after(:build) do |cimg|
      cimg.stub(:validate_img).and_return true
    end
  end
end

edited Aug 07 '14 at 02:46

lulalala

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answered Jan 31 '12 at 00:51

fkreusch

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3

But *should I do it*? Or should I stub it in the spec file? – Zequez Jan 31 '12 at 01:24
2

I think that if you are repeating yourself lots of times, having a general stub make sense in this case, just make sure that :cimg_for_testing_tags has a parent factory that is not stubbed for situations in which you want to test the actual behavior. – fkreusch Jan 31 '12 at 11:08
This is an awesome technique. I've found myself struggling with a solution for this kind of situations. Thanks @fkreusch ! – josemota May 11 '12 at 19:32
6

This no longer works. As of the latest rspec this will result in the failure `"Using 'stub' from rspec-mocks' old ':should' syntax without explicitly enabling the syntax is deprecated."` Unfortunately if you switch to using the new rspec `allow()` syntax you run into a different problem because FactoryGirl does not include RSpec's methods: `NoMethodError: undefined method 'allow' for #`. Does anyone know a solution to this which works with the latest versions? – Jazz Dec 05 '14 at 19:46
3

You can do `def cimg.validate_img; true; end` and effectively stub it out without rspec. – Mladen Jablanović Jun 25 '15 at 11:53
@Jazz There's a way to use the allow syntax. See my answer. – Ho-Sheng Hsiao Jun 30 '15 at 04:18

score 5 · Answer 3 · answered Sep 05 '17 at 15:52

A factory should produce "real world" objects therefore it's a bad practice (and error prone) to change behaviour (i.e. stub) in a factory.

You can do

let(:user) instance_double(User, FactoryGirl.attributes_for(:user))

before do
  allow(user).to receive(:something).and_return('something')
end

and if your before clause gets too big you may want to extract it to a separate method or create a mock child class that overrides methods you want to stub.

score 3 · Answer 4 · answered Jun 06 '14 at 16:28

3

You might also consider using FactoryGirl#build_stubbed.

answered Jun 06 '14 at 16:28

Su Zhang

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Should I stub the model in Factory girl or in the spec file while testing?

4 Answers4

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