Replaced findDomNode with ref in order to use react-test-renderer for snapshot testing with storybook

[acailly]

I tried to use storyshots which uses react-test-renderer for snapshot testing.
Unfortunately findDomNode is not supported by react-test-renderer, but there is an alternative that works well: use a React ref.

More info on this incompatibility here: facebook/react#7371

I've included another PR of mine in order to be able to test on windows: #141

[jerairrest]

Thanks for the contribution!

[xogeny]

I'm unclear, does this actually allow snapshot testing. When I try to use react-test-renderer with version 2.5.1, I still get errors like this from deep inside react-test-renderer implying that it is unhappy when it isn't running in a browser. Am I missing something?

 ● Plots - No Points

    TypeError: Cannot read property 'length' of null

      at Object.acquireContext (node_modules/chart.js/src/platforms/platform.dom.js:189:19)
      at Chart.construct (node_modules/chart.js/src/core/core.controller.js:72:27)
      at new Chart (node_modules/chart.js/src/core/core.js:7:8)
      at ChartComponent.renderChart (node_modules/react-chartjs-2/lib/index.js:303:29)
      at ChartComponent.componentDidMount (node_modules/react-chartjs-2/lib/index.js:124:12)
      at node_modules/react-test-renderer/lib/ReactCompositeComponent.js:264:25
      at measureLifeCyclePerf (node_modules/react-test-renderer/lib/ReactCompositeComponent.js:75:12)
      at node_modules/react-test-renderer/lib/ReactCompositeComponent.js:263:11

[MOZGIII]

Same error. Any idea on how to fix it?

[glubb92]

We are running into the same issue. Does somebody have an idea how to fix it?