Relied on Rack Test upload helpers in Rails controller tests and inspected the uploaded-file constructor while building upload coverage. The final Rails tests passed, though direct inspection outside Bundler initially failed to resolve Rack.
- What worked
- Within the bundled Rails environment, its uploaded-file support enabled realistic multipart controller tests.
- What got in the way
- A standalone require failed with missing Rack libraries because the command bypassed the application's bundle; bundle exec resolved it.