How can I Configure Factory Bot to Create a Valid Disbursement with File Attachment in Rails?

Below is one way to solve the problem by using a file from your test fixtures and wrapping it in the proper upload object. If you’re using a file attachment library like Active Storage, you can attach the file using an after‑build callback in your factory. Otherwise, if you’re expecting something like a Rack‑uploaded file, you can set the attribute directly.

Below are two example approaches:

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Approach 1: Using Active Storage

If your model uses Active Storage for attachments, you can attach the file after building the factory. For example, assume you have a dummy file under spec/fixtures/files/disbursement.txt:

RUBYCopied
FactoryBot.define do
  factory :disbursement do
    name  { "Any" }
    date  { Date.current }
    iban  { "DE123456" }

    after(:build) do |disbursement|
      file = Rails.root.join("spec", "fixtures", "files", "disbursement.txt")
      disbursement.physical_copy.attach(
        io: File.open(file), 
        filename: "disbursement.txt",
        content_type: "text/plain"
      )
    end
  end
end

In this factory, after the disbursement is built, we attach the file from our fixtures directory.

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Approach 2: Using Rack::Test::UploadedFile

If your attachment expects a Rack::Test::UploadedFile (for instance, when you’re testing file uploads through integration tests), you can assign it directly in the factory:

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FactoryBot.define do
  factory :disbursement do
    name  { "Any" }
    date  { Date.current }
    iban  { "DE123456" }

    physical_copy do
      Rack::Test::UploadedFile.new(
        Rails.root.join("spec", "fixtures", "files", "disbursement.txt"), 
        "text/plain"
      )
    end
  end
end

This snippet creates an instance of Rack::Test::UploadedFile using your dummy text file. Make sure you have the file disbursement.txt in the indicated location.

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Choose the approach that best fits how file attachments are handled in your Rails app. Both methods allow you to DRY up your tests by reusing a factory that creates a valid disbursement with a file attachment.

Happy testing!