class Capybara::RackTest::Form::NilUploadedFile

which should probably be provided to Rack::Test in its non-GET request methods.
That check should be based solely on the form element’s ‘enctype’ attribute value,
the class specifically when determining whether to construct the request as multipart.
This only needs to inherit from Rack::Test::UploadedFile because Rack::Test checks for

def content_type; 'application/octet-stream'; end 

def content_type; 'application/octet-stream'; end

def initialize 

def initialize
  @empty_file = Tempfile.new('nil_uploaded_file')
  @empty_file.close
end

def original_filename; ''; end 

def original_filename; ''; end

def path; @empty_file.path; end 

def path; @empty_file.path; end

def read; ''; end 

def read; ''; end

def size; 0; end 

def size; 0; end