This is not a test that I got taught about as a student, but it does seem to be popular among podiatrists outside the USA and by physical therapists worldwide. The lunge test is a weight bearing test for the ankle joint range of motion. This video desrcbes it:
Normally you would want to see the knee go past the foot around at least 4 inches in an average height person. If not, then stretching and a heel raise may be indicated. I also like to do this test with the shoes on and the orthotics in the shoe. The lunge test is useful, especially in athletes.