WETHMock withdraw function unnecessary safe math

[code423n4]

Handle

pants

Vulnerability details

Since you are using solidity version >= 0.8.0 you have additional underflow / overflow checks that takes gas cost.
Here I talk about the WETHMock.withdraw where you first require(balanceOf[msg.sender] >= wad) and then compute balanceOf[msg.sender] - wad
without using unchecked{...} keyword to save gas.
Using this unchecked{...} keyword can help to save gas (SLOAD) of this important function.

This issue also appears at WETHMock.transferFrom, lines 75 and 78.

[adrien-supizet]

Gas optimizations for mock contracts are pointless, this kind of contract is only used for local tests as shown in the project.

[alcueca]

The wardens are expected to audit everything that has been submitted by the sponsor, and not make assumptions of what is in and out of scope, even if seemingly obvious.