Coded UI now supports UI automated tests for Windows phone 8. It can be run in emulator, so you won't need an actual device.
To start with Coded UI tests for WP in your solution select File->Add->New project...
In the Add New Project
dialog select Coded UI Test Project (Windows Phone)
under Visual C#
->Windows phone Apps
node
Here is a link to Automated Testing of XAML-Based Apps for Windows and Windows Phone session by Prachi Bora
http://channel9.msdn.com/Events/Build/2014/3-593
Session summary:
Do you want to create automated tests for your apps? With Visual
Studio 2013 Update 2 you can now create automated tests for your
XAML-based Windows and Windows Phone apps. Starting from unit tests to
functional end-to-end scenario tests using coded UI tests, you can now
perform all of your testing from the integrated Test Explorer in
Visual Studio. The testing framework is extensible and developers can
customize it to meet the specialized needs of their application. In
this session, we will show you how to build comprehensive test suites
for your apps by leveraging these Visual Studio capabilities that will
help you ship a great quality app.