Tesla Inc. has expanded its testing of a ride-share app to employees in Austin, as the company pushes toward a June launch of an autonomous version of the service.

Test drivers have been used by Tesla since 2016 to fine-tune its advanced driver-assist software. However, the efforts have been intensified over the past year, four current and former employees revealed. The company aims to launch the service by June 1, insiders said to Business Insider.