Estimate test coverage for our runtime code

[gmilescu]

in #5054 and #5150 we noticed a couple of relatively easy to check corner cases which weren't caught by our test suite. Additionally, in #5121 (comment) I've noticed a branch (in a newley introduced code) which is not hit by our tests at all.

This brings up a question: how good is the coverage for our runtime logic? Given the above, I won't be surprised if we have some parts which are ignored by the tests completely.

I suggest running https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/instrument-coverage.html once to get a rough understanding of how well do we fair.

Note: I emphatically do not suggest adding some coverage checks to CI, in my experience they are more about checkbox ticking than about actual improvements in quality.

[ND-80] created by None

[gmilescu]

bowenwang1996 commented:

Assigning it to @posvyatokum given that you are working on runtime related testing

by 557058:c020323a-70e4-4c07-9ccc-3ad89b1c02ec

[gmilescu]

stale[bot] commented:

This issue has been automatically marked as stale because it has not had recent activity in the last 2 months. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

by 557058:c020323a-70e4-4c07-9ccc-3ad89b1c02ec

[gmilescu]

stale[bot] commented:

This issue has been automatically marked as stale because it has not had recent activity in the last 2 months. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

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[gmilescu]

matklad commented:

I believe we did this at some point. I remember seeing something like a `.zip` file with coverage report. We didn't act on that though.

by 557058:c020323a-70e4-4c07-9ccc-3ad89b1c02ec

[gmilescu]

Closing as duplicate of #5152.