feat(types): allow readonly namespaces in useTranslation

[belgattitude]

useTranslation() typings signature changed to allow a readonly version of namespaces argument...

Code

// From a readonly configuration. the const here is used
//  - to guarantee immutability (type level)
//  - helps typescript to narrow the type
//
export const nsConfig = ['ns1', 'ns2'] as const; 

// An example component
export const Test: React.FC = () => {
   const { t } = useTranslation(nsConfig);
   return <></>
}

Prior to this P/R, typecheck in strict mode would complain about

TS2345: Argument of type 'readonly ["common", "demo"]' is not assignable to parameter of type 'Namespace<"common" | "demo" | "home"> | undefined'.   The type 'readonly ["common", "demo"]' is 'readonly' and cannot be assigned to the mutable type '("common" | "demo" | "home")[]'.

Alternative hack:

It's possible to remove the readonly from readonly config, lacks elegance

export const nsConfig = ['ns1', 'ns2'] as const; // the `const` modifier will
type Writeable<T> = { -readonly [P in keyof T]: T[P] };
export const Test: React.FC = () => {
   const { t } = useTranslation(nsConfig as Writeable<typeof nsConfig>);
   return <></>
}

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test
• tests are included
• documentation is changed or added

[coveralls]

Coverage remained the same at 96.583% when pulling a14279c on belgattitude:typings-allow-ro-ns into c0fb97f on i18next:master.

[pedrodurek]

LGTM! 😄

[adrai]

thx, included in v11.11.1

[belgattitude]

@adrai Thanks for the speed :)

Unfortunate incompleteness in my P/R, hard to see but here's the continuation of it

feat(typings): support readonly namespaces in TFuncKey #1340