Test Your VAST Ad Response
To check whether your video ad response will work with the IMA SDK, paste your VAST ad tag or VAST ad response into the text field below and click the Test Ad button. Our video player will attempt to interpret the response, play the ad, and ping the tracking URLs. You can also test your VPAID ads by including one in your VAST response. To generate a URL which will automatically include the VAST tag, click the Generate Shareable URL button.
Go here: https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/vastinspector