Symbian OS Unit
Symbian OS Unit is an open source (thus, free) port of the popular C++ unit testing framework CxxUnit. It provides a powerful and flexible testing framework whilst requiring the minimum of developer effort to produce a library of tests. It can be used with any of the available Symbian development environments and can currently be built for the UIQ and S60 reference platforms.
Symbian OS Unit was developed and is supported by Penrillian.
Compiling and running the included "Tutorial" project (requires /X fix for Symbian 9+) quickly demonstrates this solution.