Register Node Module Manually
As you mentioned, compiling works fine - this is just a question of availability of .d.ts files.
What you want to do is alter module import at runtime, in other words alter the behaviour of the nodejs require function since
import {MessageSender} from "messages";will be transpiled in javascript (ES6) to something like
const messages_1 = require("messages");...messages_1.MessageSenderTo modify that behaviour, the first thing that springs to mind is to use the deprecated - but still available - require.extensions object.
When running locally you must first inject something like
require.extensions['.js'] = (module, filename) => { if (filename === 'messages') { // then load mock module/polyfill using the passed module object // see (https://nodejs.org/api/modules.html#modules_the_module_object) }};The doc says there are better alternatives but fails to clearly mention any.
Another possibility is to look at projects like sandboxed-module which should help (I have not tested it)