Metrolinx has announced that a train has successfully travelled the relatively short distance between Mount Dennis and Caledonia stations. It apparently was the furthest that an actual train has been along the line. Read more about the event here.
The line is expected to be ready for passengers in 2022. It will open as an entity rather than gradually.
The Ford government campaigned on and has made much of its commitment to extend the line westwards beyond Mount Dennis to the airport and is actively seeking proposals from potential contractors. Much of the extension will be underground, following Eglinton Avenue.