[yladiz]

I would argue that using the right words is important here. “On call” typically refers to a specific thing, where if something breaks that person on call is, well, called (or paged, etc.) to fix it when it happens, even at 2am. This is how I took the meaning of that paragraph as well.

If the author meant that code ownership is important, or that the engineer(s) who wrote the code are responsible, that message could have been conveyed by saying, “the persons who wrote the code should test it once it’s deployed and are responsible for fixing if it breaks or is broken when deployed.” This is much clearer and doesn’t use terms that could be understood incorrectly.