formik-test-mocks.jsx

import * as React from 'react';
import * as formik from 'formik';

jest.mock('formik');

it('prints error', () => {
  formik.useFormikContext.mockResolvedValue({ errors: { hello: '' }});
  
  const { container, rerender } = render(<Formik initialValues={{ hello: '' }}><YourErrorField name="hello" /></Formik>);
  expect(container.querySelector('.error')?.textContent).toBe('');

  formik.useFormikContext.mockResolvedValue({ errors: { hello: 'error' }});
  
  rerender();

  expect(container.querySelector('.error')?.textContent).toBe('');
});

// in your actual component
import { getIn, useFormikContext } from 'formik';

const YourErrorField = (props) => {
  const formik = useFormikContext();

  return <span className="error">{getIn(formik.errors, props.name)}</span>;
}