Покрытие Jest для this.ref.getBoundingClientRect

class Tabs extends React.PureComponent {
  getTabsRef = (tabsRef) => (this.ref = tabsRef);

  handleTabIndicatorChange = ({ left, value, width }, isInitialMount) => {
    if (value !== this.props.value || isInitialMount) {
      this.props.onChange(value, left, width);
    }
  }

  renderTabs() {
    const { tabs, value } = this.props;

    return tabs.map((tab, index) => {
      return (
        <Tab
          key = {index}
          label = {tab.label}
          isActive = {value === tab.value}
          value = {tab.value}
          onChange = {this.handleTabIndicatorChange}
        />
      );
    });
  }

  render() {
    let left = 0;
    let width = 0;
    const { indicatorLeft, indicatorWidth } = this.props;

    if (this.ref) {
      const rect = this.ref.getBoundingClientRect();
      left = indicatorLeft - rect.left;
      width = indicatorWidth;
    }

    return (
      <StyledTabs className='tabs-wrapper' ref = {this.getTabsRef}>
        <ul key='tabs' className='material-tabs'>
          {this.renderTabs()}
        </ul>
        <TabIndicator key='indicator' left = {left} width = {width} />
      </StyledTabs>
    );
  }
}

Tabs.propTypes = {
  indicatorLeft: PropTypes.number,
  indicatorWidth: PropTypes.number,
  onChange: PropTypes.func,
  tabs: PropTypes.array,
  value: PropTypes.oneOfType([
    PropTypes.string,
    PropTypes.number,
  ]),
};

Tabs.defaultProps = {
  onChange: Function.prototype,
  tabs: [],
  value: 0,
  indicatorLeft: 0,
  indicatorWidth: 0,
};

export default Tabs;

  it('should set indicator based on ref', () => {
    const props = getProps();
    const wrapper = shallow(<Tabs {...props} />);

    wrapper.instance().getTabsRef(ref);
    expect(wrapper.instance().ref).toBe(ref);