The testing phase is almost the most important in a project. The results obtained during the tests will determine the success or the failure.
Maybe it is not necessary to test the parachute bought in a shop. However, when you make one by yourself it is advisable. Since we don’t have the same materials (as well as experience) we will not be able to know if the parachute will work properly or not. Geometry, materials, the way to sew… All these things have influence in the flight.
First of all, we should think about what we want to check and what kind of equipment we need. For example, we could make a resistance test producing high-speed gusts of wind and registering with a dynamometer the magnitude of the forces. We also could study the parachute’s descent with different weights and altitudes. Is there any relationship between the weight, the descent velocity, and the deviation from the launch place?
Here it is a video of a group of students testing their CanSat parachute with an octocopter: