How to use the etch.updateSync function in etch

elementAttached() {
    // Re-render when the dock is attached to make sure we remeasure sizes defined in CSS.
    etch.updateSync(this);
  }

update (newProps) {
    if (this.shouldUpdate(newProps)) {
      this.props = newProps
      etch.updateSync(this)
    }
  }

reset () {
    this.stack = []

    this.info = {}
    etch.updateSync(this)
  }

update (props) {
    this.props = props
    etch.updateSync(this)
  }

constructor (props) {
    this.props = props
    this.element = this.props.element
    this.virtualNode = $.div(null)
    this.virtualNode.domNode = this.element
    etch.updateSync(this)
  }

spyOn(etch, 'update').andCallFake(component => {
      return etch.updateSync(component)
    })
  })

update (props) {
    if (props.measuredContent) {
      this.props = props
      etch.updateSync(this)
    }
  }

spyOn(component, 'selectionDidChange').andCallFake(() => {
        return etch.updateSync(component)
      })

update (props) {
    if (this.shouldUpdate(props)) {
      this.props = props
      etch.updateSync(this)
    }
  }

spyOn(etch, 'update').andCallFake(component => {
        return etch.updateSync(component)
      })