I have an Typescript axios interceptor function file. This is mostly the generic Jhipster code with modification to support polling based on 202 HTTP status code in the response.

import axios, { type AxiosError } from 'axios';

const TIMEOUT = 1 * 60 * 1000;
axios.defaults.timeout = TIMEOUT;
axios.defaults.baseURL = SERVER_API_URL;

const setupAxiosInterceptors = onUnauthenticated => {
  const onRequestSuccess = config => {
    return config;
  };
  const onResponseSuccess = async response => {
    if (response.status === 202) {
      const pollingResponse = await startPolling(response.headers.location);
      if (pollingResponse.data.status === 'ACCEPTED') {
        throw new Error('Operation failed! ' + response.headers.location);
      } else {
        return pollingResponse;
      }
    }
    return response;
  };

  const onResponseError = (err: AxiosError) => {
    const status = err.status || (err.response ? err.response.status : 0);
    if (status === 401) {
      onUnauthenticated();
    }
    return Promise.reject(err);
  };
  axios.interceptors.request.use(onRequestSuccess);
  axios.interceptors.response.use(onResponseSuccess, onResponseError);
};

async function startPolling(url) {
  const pollingInterval = 100; // interval between polls in milliseconds
  const maxPollingTime = 10000; // maximum polling time in milliseconds (15 seconds)

  let result = null;
  let stopPolling = false;

  const startTime = Date.now();

  while (!stopPolling) {
    try {
      const currentTime = Date.now();
      const elapsedTime = currentTime - startTime;

      if (elapsedTime >= maxPollingTime) {
        console.warn('Polling stopped due to time limit exceeded');
        break;
      }

      const response = await axios.get(url);
      const status = response.data.entityStatus;
      /* eslint-disable no-console */
      console.log('Response status: ', status);
      if (status === OK) {
        stopPolling = true;
        result = response;
        /* eslint-disable no-console */
        console.log('Pending job finished', status);
      } else {
        await new Promise(resolve => setTimeout(resolve, pollingInterval));
      }
    } catch (error) {
      console.error(error);
    }
  }
  return result;
}

export default setupAxiosInterceptors;

After adding polling functionality, standard JHipster tests related to axios started to fail.

import axios from 'axios';
import sinon from 'sinon';

import setupAxiosInterceptors from './axios-interceptor';

describe('Axios Interceptor', () => {
  describe('setupAxiosInterceptors', () => {
    const client = axios;
    const onUnauthenticated = sinon.spy();
    setupAxiosInterceptors(onUnauthenticated);

    it('onRequestSuccess is called on fulfilled request', () => {
      expect((client.interceptors.request as any).handlers[0].fulfilled({ data: 'foo', url: '/test' })).toMatchObject({
        data: 'foo',
      });
    });
  });
});

with an error:

   SyntaxError: srcmainwebappappconfigaxios-interceptor.spec.ts: Unexpected token, expected "," (13:42)

      11 |
      12 |     it('onRequestSuccess is called on fulfilled request', () => {
    > 13 |       expect((client.interceptors.request as any).handlers[0].fulfilled({ data: 'foo', url: '/test' })).toMatchObject({
         |                                           ^
      14 |         data: 'foo',
      15 |       });
      16 |     });

I`m mostly doing backend development and cannot figure out what I need to change to make it work.