Tidak dapat menemukan tombol untuk mensimulasikan klik - Unit Testing React w/ Mocha, Chai, Enzyme

Saya mencoba mensimulasikan klik tombol dengan Enzim. Saya sudah bisa menulis tes sederhana jika suatu elemen dirender, namun tes menyenangkan seperti klik tombol dll. gagal.

Dalam contoh ini kesalahan di terminal adalah:

 1) Front End @Profile Component clicks a button :
 Error: This method is only meant to be run on single node. 0 found instead.
  at ShallowWrapper.single (node_modules/enzyme/build/ShallowWrapper.js:1093:17)
  at ShallowWrapper.props (node_modules/enzyme/build/ShallowWrapper.js:532:21)
  at ShallowWrapper.prop (node_modules/enzyme/build/ShallowWrapper.js:732:21)
  at ShallowWrapper.simulate (node_modules/enzyme/build/ShallowWrapper.js:505:28)
  at Context.<anonymous> (cmpnt-profile.spec.js:36:32)

tes unitnya adalah:

      describe('Front End @Profile Component', () => {
      const wrapper = shallow(<Profile/>);

     ...(other tests here)...
        it('clicks a button ', () => {

        wrapper.find('button').simulate('click');
        expect(onButtonClick.calledOnce).to.equal(true);
    })
});

komponennya adalah:

import _ from 'lodash';
import React, { Component, PropTypes } from 'react';
import { reduxForm } from 'redux-form';
import ExpireAlert from '../components/alert';
import SocialAccount from '../components/socialAccounts'

const FIELDS = {
    name : {
        type : 'input',
        label : 'name'
    },
    username : {
        type : 'input',
        label: 'username'
    },
    email : {
        type : 'input',
        label: 'email'
    }
};

let alert = false;

export default class Profile extends Component {

    componentWillReceiveProps(nextProps){
      if(nextProps.userIsUpdated){
        alert = !alert
      }
    }

    handleSubmit(userData) { // update profile
     userData.id = this.props.userInfo.id
     this.props.updateUserInfo(userData)
    }

    renderField(fieldConfig, field) { // one helper per ea field declared
      const fieldHelper = this.props.fields[field];
      return (
        <label>{fieldConfig.label}
          <fieldConfig.type type="text" placeholder={fieldConfig.label} {...fieldHelper}/>
          {fieldHelper.touched && fieldHelper.error && <div>{fieldHelper.error}</div>}
        </label>
      );
    }

  render() {
    const {resetForm, handleSubmit, submitting, initialValues} = this.props;
      return (
        <div className="login">
          <div className="row">
            <div className="small-12 large-7 large-centered columns">
              <div className="component-wrapper">
                <ExpireAlert 
                    set={this.props.userIsUpdated}
                    reset={this.props.resetAlert}
                    status="success"
                    delay={3000}>
                    <strong> That was a splendid update! </strong>
                </ExpireAlert>
                <h3>Your Profile</h3>
                <SocialAccount
                  userInfo={this.props.userInfo}
                  unlinkSocialAcc={this.props.unlinkSocialAcc}
                />
                <form className="profile-form" onSubmit={this.props.handleSubmit(this.handleSubmit.bind(this))}>
                  <div className="row">
                    <div className="small-12 large-4 columns">
                      <img className="image" src={this.props.userInfo.img_url}/>
                    </div>
                    <div className="small-12 large-8 columns">
                      {_.map(FIELDS, this.renderField.bind(this))}
                    </div>
                    <div className="small-12 columns">
                      <button type="submit" className="primary button expanded" disabled={submitting}>
                        {submitting ? <i/> : <i/>} Update
                      </button>
                    </div>
                  </div>
                </form>
              </div>
            </div>
          </div>
      </div>
   );
  }
}

const validate = values => {
  const errors = {}
     if (!values.name) {
        errors.name = 'Name is Required'
      }
      if (!values.username) {
        errors.username = 'Username is Required'
      } else if (values.username.length > 30) {
        errors.username = 'Must be 30 characters or less'
      }
      if (!values.email) {
        errors.email = 'Email is Required'
      } else if (!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i.test(values.email)) {
        errors.email = 'Invalid email address'
      }
  return errors;
}

Profile.propTypes = {
  fields: PropTypes.object.isRequired,
  handleSubmit: PropTypes.func.isRequired,
  resetForm: PropTypes.func.isRequired,
  submitting: PropTypes.bool.isRequired
}

export default reduxForm({
  form: 'Profile',
  fields: _.keys(FIELDS),
  validate
})(Profile)

Setiap saran dihargai. Saya ingin membuat beberapa pengujian unit yang luar biasa!