Lesson 9: 15:52:08; AssertionError: Expected transaction to be reverted with reason...

[CryptoNube]

https://youtu.be/gyMwXuJrbJQ?t=57128
Hi fam!

When writing a unit test, I accidentally discovered something through a spelling mistake.
I miss-spelled "nonexistent" with "non-existent".

When using non-existent, after running:

yarn hardhat test --grep "can only be called after performUpkeep"

I received an error in the terminal stating:

AssertionError: Expected transaction to be reverted with reason 'non-existent request', but it reverted with reason 'nonexistent request'

This error alerted me into changing non-existent to nonexistent.

When using nonexistent, after running:

yarn hardhat test --grep "can only be called after performUpkeep"

the test passed successfully.

QUESTION:
I am not stuck, everything is working fine, but, I am wondering...
...where does this,

reverted with reason 'nonexistent request'

come from?

In other words, How does one know to write the revertedWith() message as, "nonexistent request", as opposed to anything else?
e.g. "no request exists", "no request", "non-existent request" or, whatever else for that matter.

Error:

Pass:

[CryptoNube]

Nevermind!
Right after I posted this, I realized that I forgot to check the VRFCoordinatorV2Mock.sol contract from "@chainlink/contracts/src/v0.8/mocks/VRFCoordinatorV2Mock.sol";
Indeed that is where the revert("nonexistent request"); comes from.

P.S.
I wish you could delete discussions in github because of things like this 🥴

[aaankeet]

@CryptoNube The error message must matches the error message that you are expecting from you smart contract. Since you are testing your smart contract's behavior for Reverts.

[aaankeet]

So nonexistent request is the actual error message that you have defined in your smart contract for error handling.

[CryptoNube]

Yes, I thought that.
Then, I confused myself when I couldn't find where it came from.
However, now I know this for fact.
So, thank you!