LESSON 9: Mock VRF why is random deterministic?

[0xCardiE]

So in Video when we are writing test "picks a winner, resets, and sends money"
we are counting on the winner being account number 1

const winnerBalance = await accounts[1].getBalance();

and in github repo it is number 2

const winnerBalance = await accounts[2].getBalance();

So I wonder why there is the difference and also, why is it deterministic and always the same, where does randomness come from in mock?

[krakxn]

Hey, I recall Patrick explaining why so in a discussion. I will rephrase it.

Yes, your curiosity is valid - it is because for our Mock, it is not random, ie, it is deterministic. It always returns the same winner, there is no randomness involved. Hope this answers your doubt!

[0xCardiE]

But actually its not always returning same winner at least its different in video and in GH repo, so was wondering where does the difference come from

[alymurtazamemon]

@adriadrop In the video Patrick used a deployer account everywhere that was account no 0 but in the GitHub repo in beforeEach, it is player from account no 1 that is why you are seeing 2 instead of one and you can see in the video Patrick starts loop from index 1 but in the repo, it is from 2. It is the only reason you can remove the player account and use deployer as in video as use 1 instead of 2 everywhere.

And now come the part, why we have fix number? so in mocks, it does not change it every time returns the same while but in the testnet it will.