Typescript: how do I declare a global variable without using as any?

Question

I'm trying to write some unit tests for some legacy JavaScript code, and I want these unit tests to use TypeScript so i can have some sort of type safety. I pull this off by loading a global file before my tests run. It looks like this:

(global as any).setup = {};

(global as any).State = {
  variables: {},
};

This works fine, but I don't like how i'm using any there, and I'd like to use a real type instead. Here was my attempt to do so:

/* eslint-disable @typescript-eslint/no-explicit-any */
console.log("global");

(global as any).setup = {};

interface SugarcubeVariables {

}

interface SugarcubeState {
    variables: SugarcubeVariables;
}

State: SugarcubeState = {
  variables: {},
};

With this change, I get to errors that I don't know how to resolve.

1. State has an error that says: State is defined but never used.
2. SugarcubeState has an error that says: SugarcubeState is not defined

That 2nd one is more confusing to me, because I have an interface definition right above it.

If I put a const in front of State, the errors turn into a warning: State is assigned a value but never used.

In my test, I have a line like this: const State = (global as any).State; Before I modified anything above, this worked fine, but now that I've changed State in the global file, I don't know how to refer to it anymore.

I can't tell if I'm going about this completely wrong or I'm getting closer to solving the problem. How can I modify (global as any).State in the global file so that it's no longer using any, but it's still a global variable?