Starbucks has gone cashless at one location in downtown Seattle as the coffee giant experiments with a growing trend among fast casual chains in the U.S.

The Seattle Times first made the discovery and reported that Starbucks is testing the concept at only one store. A Starbucks spokeswoman told the outlet that the test is limited to just one location, but did not say how long it will last or if it will expand to other locations.

"The test will help us understand how cashless forms of payment may impact our customer experience," the spokeswoman told the Seattle Times.

Starbucks sees some 30 percent of its transactions come from its popular mobile app.