PSA: Test coverage in Gerrit for arm64 support

[Shai Barack]

If you don't write code that behaves differently on arm64 vs x64 then you can stop reading now.

Tl;dr you can now get combined x64+arm64 test coverage in Gerrit, but you need to push a button.

Test coverage in Gerrit is a popular feature that automatically takes your code when you upload it, builds and runs it, and then shows you which lines in your change are tested and which lines are not right inside the review UI. Coverage can be part of the review conversation for the author and the reviewers to gawk at.

Absolute coverage is what percentage of lines in the file are tested.

Incremental coverage is of the lines that are modified in this change, how many are covered. If incremental coverage in your change is 100% then it means that all the code you're touching is tested - nice!

We take some shortcuts for performance reasons. For instance we collect absolute coverage reports from both x64 and arm64, but for Gerrit incremental coverage we only collect x64.

It's now possible to get coverage for arm64 as well. It's opt-in and you need to follow some simple instructions.

If you're developing architecture-specific code then this may be helpful to you.

Every time you trigger this tryjob on a change an angel gets their wings the Test Coverage working group gets a data point. If you'd like to see arm64 support become the default then please use this feature and provide us with more data.