axios_interceptor_test.js

const axios = require('axios').default;

let callCounter = {};
const displayCalls = () => {
  console.log(callCounter);
};
function makeInterceptor(keyName, returns) {
  callCounter[keyName] = 0;
  return (r) => {
    callCounter[keyName]++;
    switch (returns) {
      case 'response':
        return r;
      case 'reject':
        return Promise.reject();
      default:
        break;
    }
  };
}

const returnsResponse = axios.create();
returnsResponse
  .interceptors.response.use(makeInterceptor('returnsResponse first', 'response'), null);
returnsResponse
  .interceptors.response.use(makeInterceptor('returnsResponse second', 'response'), null);

const noReturn = axios.create();
noReturn
  .interceptors.response.use(makeInterceptor('noReturn first', 'no response'), null);
noReturn
  .interceptors.response.use(makeInterceptor('noReturn second', 'no response'), null);

const errorInterceptorReturnsRejectedPromise = axios.create();
errorInterceptorReturnsRejectedPromise
  .interceptors.response.use(null, makeInterceptor('errorInterceptorReturnsRejectedPromise first', 'reject'));
errorInterceptorReturnsRejectedPromise
  .interceptors.response.use(null, makeInterceptor('errorInterceptorReturnsRejectedPromise second', 'reject'));

const errorInterceptorReturnsResponse = axios.create();
errorInterceptorReturnsResponse
  .interceptors.response.use(null, makeInterceptor('errorInterceptorReturnsResponse first', 'response'));
errorInterceptorReturnsResponse
  .interceptors.response.use(null, makeInterceptor('errorInterceptorReturnsResponse second', 'response'));

const errorInterceptorDoesntReturn = axios.create();
errorInterceptorDoesntReturn
  .interceptors.response.use(null, makeInterceptor('errorInterceptorDoesntReturn first', 'no response'));
errorInterceptorDoesntReturn
  .interceptors.response.use(null, makeInterceptor('errorInterceptorDoesntReturn second', 'no response'));

Promise.allSettled([
  returnsResponse.get('http://example.com'),
  noReturn.get('http://example.com'),
  errorInterceptorReturnsRejectedPromise.get('http://ajfalfjdalfjalfjalsdjf.com'),
  errorInterceptorDoesntReturn.get('http://ajfalfjdalfjalfjalsdjf.com'),
])
  .then(displayCalls)
  .catch(displayCalls);

/**
 * Results
 *{
    'returnsResponse first': 1,
    'returnsResponse second': 1,
    'noReturn first': 1,
    'noReturn second': 1,
    'errorInterceptorReturnsRejectedPromise first': 1,
    'errorInterceptorReturnsRejectedPromise second': 1,
    'errorInterceptorReturnsResponse first': 0,
    'errorInterceptorReturnsResponse second': 0,
    'errorInterceptorDoesntReturn first': 1,
    'errorInterceptorDoesntReturn second': 0
  }
 */