adding to an existing Object prototype in typescript

I'm using the fantastic Wallaby testing solution to run realtime tests but it -- by default -- intercepts stdout and stderr (for good reasons). In the cases where I do not want this to happen I can override the behavior by tucking a variable into the console command like so:

console._restored = true;

this will be picked up by the Wallaby test runner and temporarily send the event streams back to their normal destinations. This solution works just fine but Typescript isn't happy:

I am trying to find some way in which to add to the prototype definition of the "Console" interface.

In my first crude attempt, I just looked up the NodeJS definition of Console and added to my test helper file with the _restored property added:

As with most cases of desperation it ended in tears. Apparently the already defined global definition is still used.

Anyway, any help would be appreciated.

My initial attempt was actually close to being right. You can redefine the interface Console as:

// tslint:disable-next-line
interface Console {
    _restored: boolean;
    Console: typeof NodeJS.Console;
    assert(value: any, message?: string, ...optionalParams: any[]): void;
    dir(obj: any, options?: {showHidden?: boolean, depth?: number, colors?: boolean}): void;
    error(message?: any, ...optionalParams: any[]): void;
    info(message?: any, ...optionalParams: any[]): void;
    log(message?: any, ...optionalParams: any[]): void;
    time(label: string): void;
    timeEnd(label: string): void;
    trace(message?: any, ...optionalParams: any[]): void;
    warn(message?: any, ...optionalParams: any[]): void;
}

But then you must also declare console as your newly defined interface:

declare var console: Console;

With this defined in my test helper file, I can now add the following function without error:

export function restoreStdoutAndStderr() {
  console._restored = true;
}