Ruby Quicktips - Testing CSV file uploads

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Testing CSV file uploads

Let’s say you have a form like this for uploading a CSV file:

<%= form_tag csv_import_path, :multipart => true do %>
  <%= file_field_tag :file, :accept => "text/csv" %>
  <%= submit_tag "Upload" %>
<% end %>

And your controller action looks like this:

require 'csv'

def csv_import    
  file_data = params[:file].read
  csv_rows  = CSV.parse(file_data)

  csv_rows.each do |row|
    # do something with each row
  end
    
  respond_to do |format|
    format.html { redirect_to your_path, :notice => "Successfully imported the CSV file." }
  end
end

How would you test this functionality?

You can’t use fixture_file_upload and stick a sample file in test/fixtures/files/ (as often suggested - e.g. here on SO). That’s because CSV and YAML files will be imported as fixtures into the test database as soon as you run tests. E.g., this would not work:

def test_file_upload
  post :csv_import, :file => fixture_file_upload('files/new_users.csv','text/csv')
end

But what you can do is to use the Tempfile and Rack::Test::UploadFile classes and manually create a CSV file and supply this to the post (or put) method:

def test_should_successfully_import_csv
  csv_rows = <<-eos
Name1,[email protected]
Name2,[email protected]
Name3,[email protected]
eos

  file = Tempfile.new('new_users.csv')
  file.write(csv_rows)
  file.rewind

  assert_difference "User.count", 3 do
    post :csv_import, :file => Rack::Test::UploadedFile.new(file, 'text/csv')
  end

  assert_redirected_to your_path
  assert_equal "Successfully imported the CSV file.", flash[:notice]
end

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