by Jay Holtslander on WordPress.org
Adds a “Test Data” link in the admin bar (when viewing any page or post) which opens the current URL in Google's Structured Data Testing Tool.

Adds a “Test Data” link in the admin bar (when viewing any page or post) which opens the current URL in Google’s Structured Data Testing Tool. (You must have the admin bar enabled to see it.)
Structured data markup describes things on the web, along with their properties. For example, if your site has recipes, you could use markup to describe properties for each recipe, such as the summary, the URL to a photo for the dish, and its overall rating from users.
When you provide structured data markup for your online content, you make that content eligible to appear in two categories of Google Search features: