How to test gyroscope, accelerometer and filter?

You may rotary index. I took one from university's workshop and it helps a lot. It helps you to see the accuracy of the gyroscope, accelerometer and your filter. I have to say that it does not help with raw data from gyroscope it helps with the angle output base on gyroscope alone. you can use the following formula and test your gyroscope, just make sure that initial value for   previous_angle is equal to zero and then angle change is reading from gyro and it gives you the angle. you have to keep the reading from rotary index and consider it as a zero at the time that you first turn on your sensor. This will even give you the idea that how gyro is drifting. If you rotate it at a faster, it will drift faster too.
angle = previous_angle + angle_change
For accelerometer the reading from sensor should be equal to rotary index.
For filter output, the reading  rotary index should be equal to filter output.