Lesson 10 - script/mockOffchain.js vs VRFCoordinatorV2Mock.sol ? are they same ?

[tsuccar]

we are supposed to run script/mockOffchain.js to test Chainlink upkeep and VRF functionalities. I thought that we are already integrated "VRFCoordinatorV2Mock.sol " to mock or simulate on localhost. What does script/mockOffchain.js do that VRFCoordinatorV2Mock.sol doesn't ?

[RoboCrypter]

@tsuccar : mockOffChain.js mock the Chainlink VRF and Chainlink Keepers, and gives us the random lottery winner!

We use mockOffChain.js when we are on our frontend to check to see, that if it is picking up the random winner!

[tsuccar]

@abossofmyself @krakxn
I see. I'm still trying to understand Chainlink upKeep & VRF "Simulation" part correctly. In Chap 9, we ran unit test and achieved some Chainlink level of simulation there. My assumption was that vrfCoordinatorV2Mock took care of all simulations needed incorrectly. So, if I can reframe my question, Can we reuse those unit tests in Chap9 in Chap10 as well instead of this script ? for example if we were to run yarn hardhat test --network localhost without this additional script. what would be missing that this script is bringing ? I'm trying to understand what this script is doing that were not simulating before

My 2nd Question, mockOffchain.js also uses vrfCoordinatorV2Mock as in :

const vrfCoordinatorV2Mock = await ethers.getContract("VRFCoordinatorV2Mock")

does that mean that the yarn hardhat node also deploys the mock VRFCoordinatorV2Mock , although we did not use the tag explicitly to deploy it?

[krakxn]

"Can we reuse those unit tests in Chap9 in Chap10 as well instead of this script ?" Unit tests serve to "test" the logic of the specific code, and also cannot be used specifically as a script.

"what would be missing that this script is bringing ?" The context-specific conditionals, which in this case is related to upkeep.

"I'm trying to understand what this script is doing that were not simulating before" As above, we did not include any context-specific conditionals for upkeep; this one is specific (i.e. upkeep) for integration w/ the front-end.

As for your second question, yarn hardhat node essentially creates a "fresh" blockchain. As so, it is inclusive of deploying any contracts in the directory. Therefore, it deploys VRFCoordinatorV2Mock

[krakxn]

There is no similarity between them.

VRFCoordinatorV2Mock is a contract, and used for randomness (i.e. fulfillRandomWords). Essentially, it is a random function (VRF = verifiable random function).

Whereas, mockOffchain is a script, and used arbitrarily w/ its logic primarily as a conditional ("checker") for upkeep; ultimately, used for integration w/ the front-end section.