ReactWrapper.update() is not forcing a re-render

Current behavior

min-repro here: https://github.com/nicholasrice/enzyme-react-wrapper-update-repro

Using mount to mount a component, calling the update method of the returned ReactWrapper instance does not seem to be forcing a re-render. With slight changes, I implemented the example from https://airbnb.io/enzyme/docs/api/ReactWrapper/update.html and am expierencing a test failure.

On a slight aside, I think the assertions being made in the above documentation should be 1 for the first call and 2 for the second call, instead of 0 for the first call and 1 for the second.

const React = require('react');
const Enzyme = require('enzyme');
const Adapter = require('enzyme-adapter-react-16');

Enzyme.configure({ adapter: new Adapter() });

test("ReactWrapper.update should re-render a react component", () => {
    const spy = jest.fn();

    class ImpureRender extends React.Component {
        constructor(props) {
            super(props);

            this.count = 0;
        }

        render() {
            this.count += 1;
            spy(this.count);

            return React.createElement("div", {}, this.count);

        }

    }

    const wrapper = Enzyme.mount(React.createElement(ImpureRender));

    expect(spy).toHaveBeenCalledTimes(1)

    // Update the component - should force re-render per https://github.com/airbnb/enzyme/blob/master/docs/api/ReactWrapper/update.md
    wrapper.update();

    expect(spy).toHaveBeenCalledTimes(2)
});

Expected behavior

I would expect that calling the update method of a ReactWrapper would call the render method of the mounted component.

Your environment

API

• shallow
• mount
• render

Version

library	version
enzyme	3.9.0
react	16.8.4
react-dom	16.8.4
react-test-renderer	16.8.4
adapter (below)	1.10.0

Adapter

• enzyme-adapter-react-16