I drove to Chicago to try out McDonald's little-known CosMc's test location. Dunkin Donuts should be on alert.

• McDonald's now has four CosMc's locations open, one near Chicago and three near Dallas.
• The chain will test 10 locations of the small-format, limited-menu restaurant concept this year.
• I visited the original Chicago location. My takeaway? Dunkin' Donuts should be on alert.

After a year of buzz, CosMc's is up and running.

McDonald's now has four locations open for testing — one near Chicago and three near Dallas — with six more Texas locations slated for this year.