Jest reports that a method from a enzyme shallowed component has not been called in componentDidMount

So I have a generic class component:

import React, { Component } from "react";

export default class CompTest extends Component {
  someFunc() {}

  componentDidMount() {
    this.someFunc();
  }

  render() {
    return <div>Hey</div>;
  }
}

and I want to check that someFunc gets called at least once (inside componentDidMount)

describe("<CompTest /> componendDidMount", () => {
  it("should call someFun()", () => {
    const wrapper = shallow(<CompTest />);
    const instance = instance();
    jest.spyOn(instance, "someFun");

    expect(instance.someFunc).toHaveBeenCalledTimes(1);
  });
});

however I am getting: Expected mock function to have been called one time, but it was called zero times.

According to enzyme v3 docs: As of Enzyme v3, the shallow API does call React lifecycle methods such as componentDidMount and componentDidUpdate.

What is wrong with my test? Thanks.