index.ts

import PartnerToken from "./PartnerToken";

var token2 = new PartnerToken("test");
token2.tokenValue.apply(console.log)

PartnerToken.ts

import * as hashjs from "hash.js";
import * as pulumi from "@pulumi/pulumi";
import * as crypto from "crypto";
import { CreateResult } from "@pulumi/pulumi/dynamic";

export type PartnerTokenResult = {
    tokenId: string;
    tokenValue: string;
}

export const generatePartnerToken = (): PartnerTokenResult => {

    const entropyLength = 20;
    const tokenIdLength = 4;

    var bytes = crypto.randomBytes(20);

    var tokenIdbytes = bytes.slice(0, tokenIdLength);
    var tokenValuebytes = bytes.slice(tokenIdLength, entropyLength);

    var tokenId = tokenIdbytes.toString('hex');
    var tokenValue = hashjs.sha256().update(tokenValuebytes).digest("hex").slice(0, 32);

    return ({
        tokenId: tokenId,
        tokenValue: tokenValue
    });
}

export class PartnerTokenProvider implements pulumi.dynamic.ResourceProvider {
    async create(_: any): Promise<CreateResult> {
        var token = generatePartnerToken();
        return { id: token.tokenId, outs: token };
    }
}

export default class PartnerToken extends pulumi.dynamic.Resource {

    public readonly tokenId: pulumi.Output<string>;
    public readonly tokenValue: pulumi.Output<string>;
    public readonly token: pulumi.Output<string>;

    constructor(name: string, props: {} = {}, opts?: pulumi.CustomResourceOptions) {
        super(new PartnerTokenProvider(), name, props, opts);
    }
}

stdout

Diagnostics:
  pulumi:pulumi:Stack (blah-dev):
    (node:15960) ExperimentalWarning: queueMicrotask() is experimental.

    error: Running program 'C:\dev\goodfellow\blah' failed with an unhandled exception:
    TypeError: Cannot read property 'apply' of undefined
        at Object.<anonymous> (C:\dev\goodfellow\blah\index.ts:5:19)
        at Module._compile (internal/modules/cjs/loader.js:722:30)
        at Module.m._compile (C:\dev\goodfellow\blah\node_modules\ts-node\src\index.ts:439:23)
        at Module._extensions..js (internal/modules/cjs/loader.js:733:10)
        at Object.require.extensions.(anonymous function) [as .ts] (C:\dev\goodfellow\blah\node_modules\ts-node\src\index.ts:442:12)
        at Module.load (internal/modules/cjs/loader.js:620:32)
        at tryModuleLoad (internal/modules/cjs/loader.js:560:12)
        at Function.Module._load (internal/modules/cjs/loader.js:552:3)
        at Module.require (internal/modules/cjs/loader.js:658:17)
        at require (internal/modules/cjs/helpers.js:22:18)