I’m working on a simple benchmarking feature for GPSTest that will measure overall error of the computed location by letting the user specify the actual location of the device (follow along at https://github.com/barbeau/gpstest/issues/168 if you’d like).

In the meantime, I created another app, GPS Benchmark, that is currently better suited for in-depth analysis:
https://play.google.com/store/apps/details?id=com.gpsbenchmark.android

However, it’s aged quite a bit and I haven’t had time to update it recently. Perhaps at some point I’ll port over all the functionality to GPSTest. I maintain both in my free time, so they tend to evolve slowly.