How can I replace a Tempfile with FactoryGirl?

Question

I'm testing a CSV uploader with rspec and I've saved a test file in /spec/fixtures that I pull into my tests with fixture_file_upload:

let(:file) do
  fixture_file_upload(
    Rails.root.join("spec/fixtures/chargeback_test.csv"),
    "text/csv"
  )
end

This works but I have the file path in each spec. I'd like to DRY out my code by putting this in a factory but I'm having trouble making FactoryGirl understand that I want a Tempfile back from FactoryGirl.create(:chargeback_csv).

I would have guessed the factory should look like this:

include ActionDispatch::TestProcess

FactoryGirl.define do
  factory :chargeback_csv, :class => "Tempfile" do
    ignore do
      path      { Rails.root.join("spec/fixtures/chargeback_test.csv") }
      mime_type { "text/csv" }
      binary    { false }
    end

    initialize_with { fixture_file_upload(path, mime_type, binary) }

  end
end

But, using this in my specs results in the following error:

Failure/Error: let(:file) { FactoryGirl.create(:chargeback_csv) }
NoMethodError:
  undefined method `save!' for #<Tempfile:0x112fec730>

Solved! The save! error is caused because FactoryGirl calls to_create on new objects that it creates. Newer versions of FactoryGirl have an option skip_create to avoid this error. I'm on an old version so I added to_create {} to the factory and all my tests are green again.

include ActionDispatch::TestProcess

FactoryGirl.define do
  factory :chargeback_csv, :class => "Tempfile" do

    to_create {}

    ignore do
      path      { Rails.root.join("spec/fixtures/chargeback_test.csv") }
      mime_type { "text/csv" }
      binary    { false }
    end

    initialize_with { fixture_file_upload(path, mime_type, binary) }

  end
end

Answer 1

Check out https://github.com/thoughtbot/factory_girl/blob/master/GETTING_STARTED.md#custom-construction. I need to run now, but 'll update this answer with specifics for your situation in a couple of hours if you haven't already figured it out.