You can now search for [mobile friendly] in Google and Google will give you a box at the top of the page letting you test any URL to see if it is mobile friendly. Here is a screen shot:
This is the same as the mobile friendly testing tool but directly in the search results page. Similar to how Google added the submit URL box to the search results page as well.
Gianluca Fiorelli posted this on Twitter asking if it is new. I do think it is relatively new...
Forum discussion at Twitter.
