grafana/packages/grafana-data/typings/jest/index.d.ts

import { Observable } from 'rxjs';

type ObservableType<T> = T extends Observable<infer V> ? V : never;

declare global {
  namespace jest {
    interface Matchers<R, T = {}> {
      toEmitValues<E = ObservableType<T>>(expected: E[]): Promise<CustomMatcherResult>;
      /**
       * Collect all the values emitted by the observables (also errors) and pass them to the expectations functions after
       * the observable ended (or emitted error). If Observable does not complete within OBSERVABLE_TEST_TIMEOUT_IN_MS the
       * test fails.
       */
      toEmitValuesWith<E = ObservableType<T>>(expectations: (received: E[]) => void): Promise<CustomMatcherResult>;
    }
  }
}