Possible to easily get completions for a given command line?

[Tim Landscheidt]

Hi,

I want to test consistency between a completion function and
a program's internal options (in this case
https://github.com/rpm-software-management/mock/blob/main/mock/etc/bash_completion.d/mock
and mock's "-r" option).

The completion code could be refactored to allow easier
tests, but for simplicity and maintainability I would really
just like to ask Bash: "What completions are there if I type
in 'mock -r ' and press TAB?" and get a list of completions.

Is this in any way possible with Bash (5.2.26)?

Tim