test/cksum: implement test_signed_checksums

[0xMillyByte]

Replaced a todo!() test with a working (and passing) implementation

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[RenjiSann]

This test is meant to re-implement the GNU test "signed" in the tests/cksum-c.sh test of the GNU testsuite.

You can take a look at it here and replicate it.

[0xMillyByte]

Thanks! i should have implemented the correct testcase now, feel free to let me know if something still needs to change

[collinfunk]

This test is meant to re-implement the GNU test "signed" in the tests/cksum-c.sh test of the GNU testsuite.

You can take a look at it here and replicate it.

Please be careful suggesting this. The test suite is still GPLv3+, and one might interpret "replicate" as creating a verbatim/modified copy of the original.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/shuf/shuf-reservoir (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/sort/sort-stale-thread-mem (fails in this run but passes in the 'main' branch)
Skip an intermittent issue tests/tail/inotify-dir-recreate (fails in this run but passes in the 'main' branch)

[sylvestre]

I will +1 Collin. please don't read the GNU code to implement this one

[0xMillyByte]

I made sure not to copy anything from the GNU implementation because of the warning in CONTRIBUTING.md, if it's still too similar however i will change it if needed

[RenjiSann]

Fair enough, I didn't think that was a problem for tests as well. I'll remember it.

[oech3]

@sylvestre How about submitting tests to GNU as you did?

[sylvestre]

@oech3 i am porting our MIT code/test to GPLv3
this way is fine