Define type of Container.get() return value with generic

[viacheslaff]

Following suggestion by @markvincze, I've changed Container.get() signature from get(name: string): any; to get<T>(name: string): T;.

This not only allows to leverage type safety of TypeScript, but requires to use it.

Previously Container type was optional

const console: Console = container.get('console');
console.log()

Now if you don't specify <Console> it'll default to {} (empty object type) and console.log() won't compile. This is not ideal but unfortunately I don't know the way to require generic type in TS. Nevertheless it achieves the goal of making type required, because without using the type you pretty much cannot use the value received from the container.

const console = container.get<Console>('console');
console.log() // works

const console = container.get('console');
console.log() // error TS2339: Property 'log' does not exist on type '{}'

[codecov]

Codecov Report

Merging #416 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #416   +/-   ##
=======================================
  Coverage   97.74%   97.74%           
=======================================
  Files         111      111           
  Lines        4251     4251           
=======================================
  Hits         4155     4155           
  Misses         96       96

Impacted Files	Coverage Δ
packages/frint/src/App.spec.ts	100% <100%> (ø)	⬆️
packages/frint/src/App.ts	99.35% <100%> (ø)	⬆️

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[fahad19]

native Console not supported? https://github.com/Microsoft/TypeScript/blob/master/src/lib/dom.generated.d.ts#L2983-L3011

[viacheslaff]

@fahad19 there're two extra fields which are accessed (logs and errors) in tests to check what was written to it. There's no way to check what output was using Console interface. Example:

https://github.com/frintjs/frint/pull/416/files#diff-68fd994dbdfd5ab333b569081667684fR28