import { Observable } from "rxjs";
/**
 * Subscribe to the given signal,
 * so you can use `expect(signal$).toEmit()` on it later.
 * @param o$ - the observable to watch
 * @returns a hot observable to test against
 */
export declare const watchSignal: <T>(o$: Observable<T>) => Observable<T>;
declare global {
    namespace jest {
        interface Matchers<R, T> {
            toEmit<T>(): Promise<R>;
            toEmitValue<T>(expectedValue: T): Promise<R>;
        }
    }
}