why to use test.sol ?

[SaiyanKarthi]

This is my day 16 of learning solidity smart contract development out of 38 hour I have completed 11.40 mins the thing which I really got confused is why we need test file cuz we instead of spending time we can simply recheck the code we wrote and even in test file we are the one who gonna give commands for example if I make mimimum usd = 5 , how did the test file know that I need 5 usd as minimum even there I need to give the command so isntead of that why cant we simply rechech that code or
am I questioning wrong cuz I fell so

[EngrPips]

We use the test file to interact with our contract to determine if the contract is behaving as expected under various conditions. Yeah, we need to provide values required to interact with our contract in the test file, but that is the exact thing anyone who interacts with our contract would as well provide values to interact with our contract

We can not merely look at our contract and say, Yes, this contract is working correctly; that is why we write the test to interact with it, see it in action, and see how it behaves.

Please ask questions if anything is still confusing.