How do I test a file upload in rails?

Question

I have a controller which is responsible for accepting JSON files and then processing the JSON files to do some user maintenance for our application. In user testing the file upload and processing works, but of course I would like to automate the process of testing the user maintenance in our testing. How can I upload a file to a controller in the functional testing framework?

Answer 1

Searched for this question and could not find it, or its answer on Stack Overflow, but found it elsewhere, so I'm asking to make it available on SO.

The rails framework has a function fixture_file_upload (Rails 2 Rails 3, Rails 5), which will search your fixtures directory for the file specified and will make it available as a test file for the controller in functional testing. To use it:

1) Put your file to be uploaded in the test in your fixtures/files subdirectory for testing.

2) In your unit test you can get your testing file by calling fixture_file_upload('path','mime-type').

e.g.:

bulk_json = fixture_file_upload('files/bulk_bookmark.json','application/json')

3) call the post method to hit the controller action you want, passing the object returned by fixture_file_upload as the parameter for the upload.

e.g.:

post :bookmark, :bulkfile => bulk_json

Or in Rails 5: post :bookmark, params: {bulkfile: bulk_json}

This will run through the simulated post process using a Tempfile copy of the file in your fixtures directory and then return to your unit test so you can start examining the results of the post.