find('.nav-tabs a', text: 'Upload').click
attach_file 'file_selector', testfile_path('foo.txt')
assert_selector 'button:not([disabled])', text: 'Start'
find('.nav-tabs a', text: 'Upload').click
attach_file 'file_selector', testfile_path('foo.txt')
assert_selector 'button:not([disabled])', text: 'Start'