API Test case Using Jest

[ArpitDadh]

I am writing the test cases for API files that are using Next.js. I have tried many ways to achieve it.
I need some help as I am not able to get the coverage of the file at all.

apiFile.js

const axios = require('axios');
import getConfig from 'next/config';

export default async (req, res) => {
  const {query: { param }} = req;
  const response = await customerInfo(param);

  if (!response.data || response.data == null) 
    res.status(200).send({ data: [], status: response.status});
  else
    res.status(200).send({ data: response.data.results, status: response.status });
};
async function customerInfo(params) {
    const { serverRuntimeConfig } = getConfig();
    const URL = serverRuntimeConfig.API;
    const config = {
      timeout: 15000,
      headers: {
        'content-type': 'application/json'
      },
    };
    const customer_id = params[0];
    const url = `${URL}/customer/${customer_id}`;
    return await axios
      .get(`${url}`, config)
      .then(response => {
        return response
      })
      .catch(function(error) {
        throw error;
      });
  }

TestFile.js

describe("api handler", () => {
    let req;
    let res;

    beforeEach(() => {
        req = {
            method: "get",
            params: {
                customer_id : 'abcdef'
            }
        };
        res = {
            status: jest.fn(() => res),
            end: jest.fn()
        }
    })
    it('It should call the Api', async () => {
        const params = {
          customer_id : 'abcdef'          }
          const { req, res } = createMocks({
              query: {
                  customer_id : 'abcdef'
              },
            });

          incidentOverview(params);  
          expect(res._getStatusCode()).toBe(200);
          expect(res._getData())
              expect.objectContaining({
                  name: "Alerts",
          });
    })
    it('Should check the result', async () => {
        const params = [ "CIDD706957"];
        const endpoint = '/customer/abcdef';
        axios.get.mockImplementationOnce(() => Promise.resolve(mockData));
        await expect(incidentOverview(params)).resolves.toEqual(mockData);
        expect(axios.get).toHaveBeenCalledWith(
            endpoint,
        );
    })

the error I am facing are:-
Received promise rejected instead of resolved Rejected to value: [TypeError: Cannot read property 'param' of undefined]
TypeError: Cannot destructure property 'serverRuntimeConfig' of '(0 , _config.default)(...)' as it is undefined.

I am really stuck need some help to get the coverage of this file and solve the errors.

Thanks in advance.