If I deploy a contract in Test Net , Will it remain in the Test Net or I have to Deploy it VIA Test Net over and over to test The contract?
What I did, I deployed the contract In the Test Net and I can do deploy it over and over and it doesnot show any warning or something like "The Contract already exists". That is why I am confused, is it okay? To deploy the contract via Test Net over and over?
It depends on how your test script is written. But a usual approach is to test contracts on an emulator (e.g. Ganache or Hardhat) - not a public testnet, and redeploy the contract before each test case.