1. In the case of unobstructed thinking, the program can be written quickly.
2. But after everyone uses it, many problems will be exposed. Bugs appear one after another, and you won't believe it's software you wrote yourself.
3. So the test also needs to be careful and test step by step. It is best to have a detailed schedule.
4. When a function is added to the program later, the test is not only to test the function, perhaps the function you add will also have an impact on the overall software.