Need a way to type provider:SOMETHING so I can `new` its children

instance.js

import { validate, IsInt, IsEmail, IsIn, IsNotEmpty } from 'class-validator';
import { Provider } from './provider';

export class InstanceConfig {
  [key:string]: number | string;

  @IsEmail()
  @IsNotEmpty()
  email: string;

  @IsInt()
  @IsNotEmpty()
  duration: number;
}

export class InstanceInstance {
  [key:string]: number | string | boolean;

  @IsNotEmpty()
  template: string;

  @IsNotEmpty()
  @IsIn(['emea', 'us-central', 'apac', 'aus-sydney'])
  region: string;

  @IsNotEmpty()
  @IsIn(['default', 'on', 'off'])
  internetAccess: string;

  @IsNotEmpty()
  smartrdp: boolean;

  @IsNotEmpty()
  @IsInt()
  idleRuntimeLimit: number;

  @IsNotEmpty()
  @IsIn(['shutdown', 'off', 'suspend'])
  idleRuntimeType: string;

  @IsNotEmpty()
  @IsInt()
  totalRuntimeLimit: number;
}

export class InstanceProvider implements Provider<InstanceConfig, InstanceInstance> {
  Config: new() => InstanceConfig;
  Instance: new() => InstanceInstance;
}

provider.js

export interface Provider<ProviderConfig, ProviderInstance> {
  Config: new () => ProviderConfig;
  Instance: new () => ProviderInstance;
}

use.js

import { InstanceProvider, InstanceConfig, InstanceInstance } from './skytap';
import { Provider } from './provider';
import { validate } from 'class-validator';

async function foo<ProviderConfig, ProviderInstance>(provider: Provider<ProviderConfig, ProviderInstance>) {
  const config = new provider.Config();
  config.email = 'foogmail.com';
  config.duration = 10;

  let errs = await validate(config, {whitelist: true});
  console.log(errs);
}


foo<InstanceConfig, InstanceInstance>(new InstanceProvider());

Thanks @chriseppstein, I'm very close, but I'm missing something and I don't quite understand what's missing. With the above (updated) code, I get the following compile errors:

Property 'email' does not exist on type 'ProviderConfig'.
Property 'duration' does not exist on type 'ProviderConfig'.

I seem to be passing everything through properly, and the type validation is now working as I expect, but the actual InstanceConfig class doesn't appear to be used for validation, so it won't let me set the properties as I expect I should be able to.

Thoughts on this last bit? Thanks!

I think I've narrowed it down to https://gist.github.com/Snugug/72a6181e6b641d9e32df126135c0ae0c#file-use-js-L5, specifically that even though I believe I'm passing the types in properly for the generic, it's not actually picking up the structure inside the function. I can confirm that this in general works because if I use InstanceProvider outside of the function call it all works as expected

While that doesn't work, InstanceProvider.Config is not a constructor so I can't new it