Jest: properly test a function branch ending in process.exit, e.g. in a CLI app

process-exit.test.js

const myFunc = function (condition) {
    console.log('before');
    if (condition) {
        process.exit(-1);
    }
    console.log('after');
}

describe('jest-process-exit test suite', () => {

    it('tests myFunc with process.exit', async (done) => {
        const mockExit = jest.spyOn(process, 'exit')
            .mockImplementation((number) => { throw new Error('process.exit: ' + number); });
        expect(() => {
            myFunc(true);
        }).toThrow();
        expect(mockExit).toHaveBeenCalledWith(-1);
        mockExit.mockRestore();
        done();
    });

});

// for more details and a full working example see: https://github.com/tsmx/jest-process-exit