The terminal waits, the prompt blinking. Your code runs, but the pipeline is quiet. You need proof—fast—that shell completion works under real conditions. This is where integration testing for shell completion becomes essential.
Integration testing shell completion means verifying that command-line autocompletion responds exactly as it should, across Bash, Zsh, and Fish, in a real shell session. Unit tests can’t catch the subtle breakpoints: environment variables not loading, mismatched command output, or scripts failing on a clean system. Only full integration tests tell you if the user experience is intact from keystroke to completed command.
Begin with a controlled environment. Use containers or lightweight VMs to mimic clean shells. Install your CLI tool the same way a user would. Enable its shell completion script, then run automated keystroke sequences that trigger completion lists. Capture the stdout. Compare actual results with expected suggestions. Any mismatch is a failure.