```javascript
function testAddReward() public {
// @audit add this to change user
vm.prank(owner);
mysteryBox.addReward("Diamond Coin", 2 ether);
MysteryBox.Reward[] memory rewards = mysteryBox.getRewardPool();
assertEq(rewards.length, 5);
// @audit It is necessary to change the ID because the constructor sets 4 slots to default values.
assertEq(rewards[4].name, "Diamond Coin");
assertEq(rewards[4].value, 2 ether);
}
```