initApollo.js

return new ApolloClient({
 link: recordRequestsInFlight(
   new HttpLink(/* ... */),
 ),
 // ...
});

recordRequestsInFlight.ts

import { ApolloLink, concat } from 'apollo-link';
import { environment } from '~/config';

declare global {
  // tslint:disable-next-line
  interface Window {
    test: {
      apolloRequestsInFlight: number;
    };
  }
}

let recordRequestsInFlight: any = (networkLink: any) => networkLink;

if (environment.isBrowser && environment.isTest) {
  recordRequestsInFlight = (networkLink: any) => {
    const recorderLink = new ApolloLink((operation: any, forward: any) => {
      window.test.apolloRequestsInFlight += 1;

      return forward(operation).map((result: any) => {
        window.test.apolloRequestsInFlight -= 1;
        return result;
      });
    });
    return concat(recorderLink, networkLink);
  };
}

export default recordRequestsInFlight;

ruby_capybara_helper.rb

# this waits until there are no upcoming XHR request
def wait_for_ajax
  Timeout.timeout(Capybara.default_max_wait_time) do
    loop while page.evaluate_script('window.test.hasInFlightRequests()')
  end
rescue Timeout::Error
  # NOTE(rstankov): Some times this fails on CI while code is working
  nil
end