Google has introduced a new AMP testing tool. You can check your AMP pages (accelerated mobile pages).
Use the following link to access new AMP testing tool.
You can also access it from Search Console.
You can use it on your mobile phone, thanks to mobile friendliness. It uses Google’s live web-search infrastructure to analyze the AMP page with the real Googlebot. This tool will test the validity of the AMP markup as well as any structured data on the page.
If the tool finds any issue, you can check it in details. The system will highlight the line in the source code, where the error is. Also, it has a link to show you, how your AMP page looks in Google search. This is how it looks.
You can also share the results with other people. Google has added a share button on the lower right side. So if you are working with a team, it will be easier to discuss the issue. This share feature is now also available in the mobile-friendly testing tool.