Agility training underpins much of rugby performance so it only makes sense to use a test to see if you are improving it from your training. A simple test that looks at lateral and backward elements of agility as well as acceleration/deceleration is the T-test.
To complete it set out the cones as shown in the diagram below. Then have someone start the stop watch on first movement and go forward 10m and touch the cone, shuffle sideways 5m to the right to touch the cone, then across 10m to the left to touch the other cone. Return to touch the middle cone and then backward run across the line with the stop watch stopping the moment you cross the line.
This test doesn’t look at the diagonal elements of agility. That can be measured using the Diamond Test