HashPairTest
├── It should never revert.
├── When first arg is smaller than second arg
│ ├── When first arg is zero
│ │ └── It should do something.
│ └── It should match the result of `keccak256(abi.encodePacked(a,b))`.
└── When first arg is bigger than second arg
└── It should match the result of `keccak256(abi.encodePacked(b,a))`.