test(unikernels): guest implementations have no unit tests, package at 9.5% coverage

[HARSHRAJ2789]

The pkg/unikontainers/unikernels package sits at 9.5% statement coverage. mirage.go and mewz.go have test files, and the rest of the guest implementations have none.

Uncovered functions per file, from go tool cover -func:

File	Functions at 0.0%	Test file
linux.go	13	none
unikraft.go	9	none (being addressed in #921)
rumprun.go	8	none
hermit_rs.go	8	none
mewz.go	7	partial
mirage.go	4	partial

I would like to start with rumprun.go. It is the guest family I have been running while working through the Argo integration in #573, so the cases would come from behaviour I have watched in a cluster.

All eight of its functions are pure, with no I/O or syscalls, which makes them straightforward to cover in the table-driven style already used by mirage_test.go and mewz_test.go:

• CommandString builds the JSON boot configuration
• Init maps UnikernelParams onto the struct
• SupportsFS gates ext2 against other filesystems, which matters because the block rootfs path in rootfs.go:233 depends on it
• MonitorNetCli, MonitorBlockCli and MonitorCli build monitor arguments
• SupportsBlock and newRumprun

Recent fixes in this area suggest the cases are worth pinning down. #823 was a subnet mask handled incorrectly in argument construction, and #747 was a redundant monitor branch. Both are the kind of thing a table test catches.

Happy to open a PR for rumprun.go if this is useful, and to follow with linux.go and hermit_rs.go if the approach looks right. Checking first in case the scope is not what you want.

[HARSHRAJ2789]

Withdrawing this. I checked which open PRs touch the package and the files are already covered:

• rumprun.go and rumprun_test.go in unikernels/rumprun: add support for multiple block devices #888
• linux.go and linux_test.go in fix(unikernels): reject single quotes in Linux init args #898, refactor(unikernels): drop redundant monitor check in Linux block cli formatting #748 and fix(unikernels): validate inputs in IsIPInSubnet #755
• unikraft_test.go in test(unikernels): add unit tests for Unikraft version parsing and command string generation #921 and fix(unikernels): use actual subnet mask in Unikraft netdev.ip args #823
• mirage.go and mirage_test.go in feat: support multiple MirageOS block devices #908
• hermit_rs.go and mewz.go in refactor: replace string concatenation in monitor CLI option construc… #858 and chore: fix typos repo-wide and close the CI spell check gap #833

I should have run that check before opening this. The coverage numbers above are still accurate if they are useful to anyone, but the work is in hand, so there is nothing here for a maintainer to triage.

Closing.

[Nachiket-Roy]

#96 already tracks this make sure to add/check items there.