Test review A-D, #259

[paulirwin]

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Test review for core A-D tests

Fixes #259 (as the final PR for this issue)

Description

Add missing comments and attributes, match formatting, remove unnecessary code, etc.

[NightOwl888]

Thanks for the PR. The final PR of #259. Nice work!

There are a few changes to make to this before we can merge it. Plus, it came to my attention that there are some other things we need to review and fix before the release that we will need some issues opened for. Please see my comments inline.

[NightOwl888]

Looks good.

Although, we may need to retitle this ReusableStringReader changed from public to internal because there is only 1 breaking change and it is more sensible to put that in the release notes than Test review A-D, #259. Or, we can move the breaking change to a different PR, which would probably look better in the release notes. Either way is fine.

[paulirwin]

Reverted breaking change and removed label, will put in a separate PR with that label. Thanks!