The first time the "Approvals.Verify" method is executed, as shown in the above line will generate a text file, in the same folder where the test class is, called:
GameTests.TestGame.received.txt . Basically, this is our copy of the working code, if we are happy, we just need to change the .received with .approved to approve the output. Once this is done, every time we run the test, ApprovalTests will compare the output with the approved file.