Jest mock values returned by function - node.js

Question

I have a logger file as below which implements logging functionality. uuidLogger.js
const winston = require('winston'),
CustomTransport = require('./customTransport');
function getLogger(route) {
return winston.createLogger({
defaultMeta: { route },
transports: [new CustomTransport()]
});
}
module.exports = getLogger;
It is imported by a function like this and used for logging testfn.js
const uuidLogger = require('./uuidLogger')('test-fn');
function testMock() {
uuidLogger.info('Hey I am just logging');
}
module.exports = { testMock };
I am trying to mock uuidlogger in testfn.js so that I can track various methods called on uuidLogger object. I tried below approach.
import { testMock } from './testfn';
import getLogger from './uuidLogger';
const logger = getLogger('testfn');
jest.mock('./uuidLogger', () =>
jest.fn(() => ({
info: jest.fn(() => console.log('Mocked function actually called'))
}))
);
it('verify that info method was called on returned object', () => {
testMock('abx');
expect(logger.info).toBeCalledTimes(1);
});
It was able to mock the method called however mock information is not getting reflected in logger.info object.
I also tried below approach
import { testMock } from './testfn';
import getLogger from './uuidLogger';
jest.mock('./uuidLogger', () =>
jest.fn(() => ({ info: jest.fn(() => console.log('Top level fn')) }))
);
const logger = {
error: jest.fn(),
info: jest.fn(() => {
console.log('Overwritten fn');
})
};
getLogger.mockReturnValue(logger);
it('shud return Winston instance', () => {
testMock('abx');
expect(logger.info).toBeCalledTimes(1);
});
Any help on how to get it will be appreciated. Thanks in advance.

Answer 1

It seems to be the assertion is not done on proper variable.
Need to assert on getLogger
Your first approach of writing test case is proper.
Add assertion something like this:
expect(getLogger.mock.results[0].value.info).toBeCalledTimes(1);