Revisit registration for parsers, formatters, versioners and validators

[ericproulx]

This PR brings a common way to load parsers, formatters, validators and middleware versioners. With this change, it facilitates the customization through inheritance.

Parsers, formatters and error formatters

Parsers, formatters and error formatters had static constant named DEFAULTS that was acting as a lookup to translate a format (:json, :xml, etc ...) to an actual class. Instead of relying on this, it will now use a dynamic registry Grape::Util::Registry that will be warmed up through inheritance like the validators (See base classes) Thus, zeitwerk, eager loads classes, so the registries are filled up when Grape is required.

Versioners

I applied the same pattern for middleware versioners since its translating a symbol to an actual class.

Validators

For the validators, I've just replace the actual registry by Grape::Util::Registry and I removed the const_get part since all validators are eager loaded.

Contract scope

I moved the contract scope validator to the validators folders and rename it to ContractScopeValidator to have a better short name than validator.

Grape::Util::Registry

ruby-grape#2437 introduced a length validator and users that already have one with the same name might not be aware that its been overridden. Giving the situation, the registry will emit a warning if an entry has changed. This is true for all classes that are using the registry.

DryTypeCoercer

I refactored the part where its was calling const_get to use a static array.

[coveralls]

Pull Request Test Coverage Report for Build 12481808979

Details

• 194 of 199 (97.49%) changed or added relevant lines in 27 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 98.335%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/grape/error_formatter/base.rb	34	35	97.14%
lib/grape/formatter/base.rb	7	8	87.5%
lib/grape/formatter/json.rb	3	4	75.0%
lib/grape/parser/base.rb	7	8	87.5%
lib/grape/validations/types/dry_type_coercer.rb	5	6	83.33%

Totals
Change from base Build 12152126541:	0.5%
Covered Lines:	3544
Relevant Lines:	3604

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💛 - Coveralls