Lifecycle methods aren't called as expected when state changes

[sawyerh]

I've upgraded from Enzyme 2.x to 3.x and noticed that tests that were previously passing now fail. I've limited these down to tests that depend on lifecycle methods like componentDidUpdate to be called.

In #1140 lifecycleExperimental was enabled by default, which to my understanding means lifecycle methods like componentDidUpdate should be called when setState is called on a shallow-rendered component. However, I am not seeing this behavior.

Even more weird: the migration guide makes it sound as if 2.x wouldn't have been calling these lifecycle methods, but I assume they were since my tests were passing before upgrading 🤔

I've created a simplified example of what I'm trying to describe here: https://github.com/sawyerh/enzyme-bug

The lifecycle method componentDidUpdate doesn't appear to be called when the component is rendered like this:

const wrapper = shallow(<Foo />);
...
wrapper.setState({...})

However componentDidUpdate does appear to be called when the component is rendered either of these ways:

1. const wrapper = shallow(<Foo />, { lifecycleExperimental: true });
2. const wrapper = mount(<Foo />);

---

Maybe related: #1201

[koba04]

@sawyerh Thanks! I've created a PR to fix this. #1261

[sawyerh]

Thanks @koba04! 🙏