refactor: 🚚 rename to extensions.py from custom_checks.py

[lwjohnst86]

Description

As per #156, renaming custom checks to be extensions instead. Will implement the Extensions class in another PR.

Needs a quick review.

Checklist

• Ran just run-all

[signekb]

Nice---should this be singular though? So extension.py and Extension rather than extensions.py and Extensions? That would mirror the singular of exclusion.py and Exclusion.

[lwjohnst86]

Exclusion is only one exclude at a time. But Extensions hold multiple extensions (required, custom, etc). Extensions can have one or more.

[signekb]

@lwjohnst86
Hmm, it doesn't feel that intuitive to me that one of them can only contain one and the other can contain multiple. What's the reasoning behind this design? :)

[lwjohnst86]

@signekb see how the config file will look: https://github.com/seedcase-project/check-datapackage/pull/156/files#diff-c4ffca5e2b64e9668128b0ab736e53790f9fc76bfd1d3c7a2e3073691a772ca0R230-R262

I agree that it feels a bit off that one is singular and the other is plural. We could rename Exclusion to be Exclusions to match the config [[exclusions]], but then the actual Exclusion can only have one exclusion. If we wanted it to have many, it would be Exclusions.exclusions=[Exclusion(...)], which is a bit redundant.

With Extensions, it has Extensions(required_checks=[required1, required2], custom_checks=[...]).

The reason for the plural is that Extensions is a meta-class that holds two (or future more) custom check classes. And the way it would be used in the config file is that it has to be able to hold multiple nested tables/classes. Otherwise it would be [[extension_required]] and [[extension_custom_check]], which to me doesn't feel very clean and we would need to implement custom logic for each new extension class.

[lwjohnst86]

@signekb and actually, the name of the parameter in Config() is exclusions and extensions, so they are both plural. Just that the Exclusion class is not.

[lwjohnst86]

@signekb and the individual extensions are singular CustomCheck and RequiredCheck.