Avoid These Junior Engineer Mistakes With Code Review
Do the work upfront to make your published code reviews look good.
If you get feedback on your code review, incorporate it directly into the current pull request to make the commenter feel heard. Don't put off the feedback by saying you will do it in a new pull request and push the commenter to allow you to land the PR.
If you just want to get high-level feedback on your approach and don't want to actually merge your PR yet, you can submit a "Request For Comment" PR, otherwise known as an RFC.
If there's no good way to test your change:
A lot of the time, there probably is. Think harder about it.
If you can't come up with anything (e.g. you did a very basic refactor), just regression test and show that the codebase still builds/the app still runs.