commerce/framework/commerce/utils/define-property.ts

// Taken from https://fettblog.eu/typescript-assertion-signatures/

type InferValue<Prop extends PropertyKey, Desc> = Desc extends {
  get(): any
  value: any
}
  ? never
  : Desc extends { value: infer T }
  ? Record<Prop, T>
  : Desc extends { get(): infer T }
  ? Record<Prop, T>
  : never

type DefineProperty<Prop extends PropertyKey, Desc extends PropertyDescriptor> =
  Desc extends { writable: any; set(val: any): any }
    ? never
    : Desc extends { writable: any; get(): any }
    ? never
    : Desc extends { writable: false }
    ? Readonly<InferValue<Prop, Desc>>
    : Desc extends { writable: true }
    ? InferValue<Prop, Desc>
    : Readonly<InferValue<Prop, Desc>>

export default function defineProperty<
  Obj extends object,
  Key extends PropertyKey,
  PDesc extends PropertyDescriptor
>(
  obj: Obj,
  prop: Key,
  val: PDesc
): asserts obj is Obj & DefineProperty<Key, PDesc> {
  Object.defineProperty(obj, prop, val)
}