wrapper.instance() is null on class component

Current behavior

wrapper.instance() and wrapper.state() are not working on a class component.

Expected behavior

wrapper.instance() and wrapper.state() work on a class component.

Your environment

I’m really confused by a component not working with instances. I have many other similar components that have a the same structure that are working. I have broken this down to a very simple component and test to show the problem.

React Component

import React from 'react';

export class EnzymeTest extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      test: true
    }
  }

  componentDidMount() {
    this.setState({test: false})
  }

  render() {
    if (this.state.test) return <div>Test is True</div>
    else return <div>Test is False</div>
  }
};

Enzyme Test

import React from 'react';
import { shallow } from 'enzyme';
import { EnzymeTest } from './EnzymeTest.js';

let wrapper;

describe('isOutsideDateRange', () => {
  beforeEach(() => {
    wrapper = shallow(<EnzymeTest /> )
  });

  beforeEach(() => {
    wrapper.unmount();
  });

  test('has state', () => {
    expect(wrapper.state('test')).toBe('blah');
  });

  test('has a wrapper instance', () => {
    expect(wrapper.instance()).toBeTruthy();
  });
});

Both of the above tests fail. The state test shows this error: ShallowWrapper::state() can only be called on class components

and wrapper.instance() in null.

This is a stateful class component so I’m confused about this behavior.

API

• [ x] shallow
• mount
• render

Version

library	version
enzyme	3.3
react	16.3.2
react-dom	16.3.2
react-test-renderer	16.3.2
adapter (below)

Adapter

• [x ] enzyme-adapter-react-16
• enzyme-adapter-react-16.3
• enzyme-adapter-react-16.2
• enzyme-adapter-react-16.1
• enzyme-adapter-react-15
• enzyme-adapter-react-15.4
• enzyme-adapter-react-14
• enzyme-adapter-react-13
• enzyme-adapter-react-helper
• others ( )

[bschmalz]

I’m not trying to test against wrapper.instance(). However, the actual component that I’m trying to test has class methods that I want to unit test, so I want to unit test them via wrapper.instance().someMethod()… bu t I can’t because wrapper.instance() returns null.

What am I doing wrong? How can I run tests against those class methods? I’m doing the same type of testing in plenty of other components so I’m confused why instance() is null in this case.

[gwhobbs]

In case it helps anyone, I was experiencing a similar problem; in my case, the issue was triggered by updating react-redux to v6 or higher, and seems to have been resolved by adding an extra .dive() to shallow wrappers on problematic tests.