Function: stake(uint256 _amount)

The msg.sender provides stakingToken to the current contract. The _totalSupply and _balances of msg.sender is increased by _amount-provided tokens. Also, the updateReward modifier is triggered.

Inputs

• _amount

  • Control: The caller has full control but cannot use more tokens than owned.

  • Constraints: If msg.sender owns less amount of stakingToken, transaction will be reverted.

  • Impact: The amount of staking tokens.

Branches and code coverage (including function calls)

Intended branches

• After first stake call, the rewards[msg.sender] is zero.

  Test coverage

• If the caller's balance is nonzero, the rewards[msg.sender] is calculated properly.

  Test coverage

Negative behavior

• Revert if msg.sender's stakingToken balance is less than _amount.

  Negative test

• _amount is zero.

  Negative test

Function call analysis

• stakingToken.safeTransferFrom(msg.sender, address(this), _amount)

  • External/internal? External.

  • Argument control? _amount.

  • Impact Transfer stakingToken from msg.sender to current contract.

• updateReward(msg.sender)

  • External/internal? Internal.

  • Argument control? N/A.

  • Impact Updates global lastUpdateTime and rewardPerTokenStored. Sets rewards and userRewardPerTokenPaid of msg.sender.