Description: Reactivity tests are a type of evaluation that focuses on measuring how quickly software responds to changes in input or its environment. This approach is crucial in the development of modern applications, where user interaction and system adaptability are fundamental. Reactivity tests allow for the identification of bottlenecks in performance and ensure that applications maintain a smooth user experience, even under changing conditions. These tests may include evaluating responses to user events, such as clicks or scrolls, as well as reactions to changes in data or system configurations. Reactivity not only refers to response speed but also to the accuracy and stability of the software in various situations. In a world where user expectations are increasingly high, reactivity tests have become an essential component of the software development lifecycle, ensuring that applications not only function correctly but also provide an optimal and satisfying user experience.