Avoid accessing browser APIs in the frontend client constructor

[platosha]

Suppose I have a module that depends on a method from an annotated service:

import {method} from './generated/MyService.js';

export class MyController {
  async myAction() {
    return await method();
  }
}

When doing frontend unit tests for that module, I want to be able to import it a Node.js environment and stub the dependencies. Currently, this is blocked because:

• importing the unit imports the generated client, there is no straightforward way to stub ES module dependencies to prevent that;
• the generated client imports the default client;
• the default client instance is created upon import;
• the client constructor attempts to restore the refresh token from localStorage synchronously, which throws.

Suggested solution: postpone restoring the refresh token to the first call instead of doing that right in the client constructor. That should enable stubbing the method before it calls browser APIs.

[manolo]

perhaps vaadin-connect could check whether window.locaStorage is available in the runtime before trying to use it.