List Wrapper Spec

list_wrapper_spec.js

import React from 'react';
import "babel-polyfill";
import listWrapper from 'list_wrapper';
import { shallow } from 'enzyme';

describe('ListWrapper', function () {
  var wrapper, ListComponent, MockListComponent, instance, set;

  beforeEach(function () {
    MockListComponent = React.createClass({
      render: function () {
        return (<div>Fake List</div>);
      },
    });

    set = new Set();
    WrapperComponent = listWrapper(MockListComponent);
    wrapper = shallow(<ListComponent />);
    instance = wrapper.instance();
  });

  it('renders the List Component as the root element', function () {
    expect(wrapper.first().is(MockListComponent)).toBeTruthy();
  });
  
  describe('handleOnSelect', function () {
    describe('when not already selected', function () {
      it('adds the key to the selection set', function () {
        instance.handleOnSelect('1234');
        expect(instance.state.selection.has('1234')).toBeTruthy();
      });
    });

    describe('when already selected', function () {
      beforeEach(function () {
        instance.setState({selection: new Set(['2314'])});
      });

      it('removes the selection from the set', function () {
        instance.handleOnSelect('2314');
        expect(instance.state.selection.has('1234')).toBeFalsy();
      });
    });
  });
});

It appears that wrong component is being passed to the shallow function in this test.
Instead of passing ListComponent into shallow it needs to pass WrapperComponent.

    WrapperComponent = listWrapper(MockListComponent);
    wrapper = shallow(<WrapperComponent />);

In fact you don't even need the ListComponent variable see the changes in my fork.