Ensure getting an array with all items of a TypeScript type

getListOfType.ts

/**
  This util is a trick to ensure you get an array with all the elements of a type.
  You have to pass an object with all the possible types as keys, and true as a value (arbitrarily chosen to be true)
*/
export const getListOfType = <A extends string>(obj: Record<A, true>): A[] => {
  return keys(obj);
};
  
function keys<O extends object>(o: O): Array<keyof O> {
  return Object.keys(o) as Array<keyof O>;
}