The old Ardupilot test suite was great, but hard to maintain. I just did a new one, but this time, I've built it into Ardupilot itself.
In your config file for 2.7 you will see DEBUG_SUBSYSTEM at the top.
Here are the values:
0 = no debug
1 = Debug the Radio input
2 = Debug the Servo output
3 = Debug the Sensor input
4 = Debug the GPS input
5 = Debug the GPS input - RAW HEX OUTPUT
6 = Debug the IMU output
7 = Debug the Control Switch
Each one will output only serial data for each subsystem, making it easy for you to isolate problems and verify things are working as they should.