"fonts" injected parameter: pass TTFont objects instead?

Observed behaviour

Check com.google.fonts/check/002 features the magic fonts parameter, which is a list of str-paths.

Expected behaviour

I’d like to get a list of TTFont/defcon.Font objects (optionally or instead) to save me the trouble of opening the fonts myself.

Maybe the parameter can be split into

• font: a TTFont/defcon.Font object, determined by the specification object. Would replace the ttFont parameter.
• fonts: a list of above, i.e. all fonts to check.
• font_paths: a list of os.PathLike objects, i.e. the file paths of the fonts.

[anthrotype]

Upon loading, fonttools should not “silently fix” anything, it should just read the incoming data. If you can show me that it is modifying things when reading, than it’s a bug and we need to fix it.

I’m a bit skeptical about the latter suggestion of checking that roundtripping through fonttools doesn’t change the output, binary-wise. FontTools can only guarantee that it will roundtrip a file that was in turn generated by the same version of FontTools. It this is not the case, then there could be some hidden bugs that prevent it from generating a deterministic output. However, things may and do change (for the better, I hope) across versions.

[graphicore]

with FontsSpec use ttFonts, it’s already there, as a “derived iterable” you can define your own derrived iterables in UfoSpec. Just like in:

https://github.com/googlefonts/fontbakery/blob/a6c76dd9ae5526019dec5d75bd610906a0afd19a/Lib/fontbakery/fonts_spec.py#L61-L67