TypeError: Cannot read properties of undefined (reading 'data')

[moezbenrebah]

Version

29

Steps to reproduce

I wrote an unit test to test the below function using axios to fetch data ( I use a json file to mock server request/response):

import axios from 'axios';

export async function updateCountryLanguage(countryName, newLanguage) {
	try {
		const response = await axios(`http://localhost:3000/countries/${countryName}`);

		// console.log('===currentLang===:', response.data.languages) // [ 'Arabic' ]
		const updatedLanguages = [ ...response.data.languages, newLanguage ];

		const updatedResponse = await axios.put(`http://localhost:3000/countries/${countryName}`, {
				...response.data,
				languages: updatedLanguages
		});
		
		console.log('Country language updated successfully:', updatedResponse.data);
	} catch (error) {
			console.error('Error updating country language:', error);
			throw error;
	}
}

updateCountryLanguage('tunisia', 'French')

I function working smoothly and without any error, also the comment log above works fine, but when it come to run the test it always complained about reading undefined from ".data"

test:

import axios from 'axios';
import { updateCountryLanguage } from './A_9';
jest.mock('axios');

describe('updateCountryLanguage', () => {
    it('should add a new language to a country successfully', async () => {
        const countryName = 'Tunisia';
        const newLanguage = 'French';
        axios.get.mockImplementationOnce(() => Promise.resolve({data: {
             languages: ['Arabic']
         }}));
        axios.put.mockResolvedValue({
            data: {
                languages: ['French']
            }
        });

        await updateCountryLanguage(countryName, newLanguage);

        expect(axios.put).toHaveBeenCalledWith(
            `http://localhost:3000/countries/${countryName}`, 
            expect.objectContaining({
                languages: expect.arrayContaining(['Arabic', 'French'])
            })
        );
    });
 });

I don't understand why it failed, and the reason behind

Expected behavior

run test successfully

Actual behavior

Cannot read properties of undefined (reading 'data')

Additional context

No response

Environment

Linux 20.04