Basic Bank V2
Let’s go deeper of the basic bank.
Overview the code
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// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.13;
contract BasicBankV2 {
/// used to store the balance of users
/// USER => BALANCE
mapping(address => uint256) public balances;
/// @notice deposit ether into the contract
/// @dev it should work properly when called multiple times
function addEther() external payable {}
/// @notice used to withdraw ether from the contract
/// @param amount of ether to remove. Cannot execeed balance i.e users cannot withdraw more than they deposited
function removeEther(uint256 amount) external payable {}
}
Problem Analysis
Compared to the previous version, an additional variable balances has been added to store the balance of each user.
When perform addEther/removeEther, we need to add/remove amount to/from the balance of that address.
CAUTION: Ensure to check the balance before transfer ether to another user.
Coding
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// SPDX-License-Identifier: BUSL-1.1
pragma solidity ^0.8.13;
contract BasicBankV2 {
/// used to store the balance of users
/// USER => BALANCE
mapping(address => uint256) public balances;
/// @notice deposit ether into the contract
/// @dev it should work properly when called multiple times
function addEther() external payable {
balances[msg.sender] += msg.value;
}
/// @notice used to withdraw ether from the contract
/// @param amount of ether to remove. Cannot execeed balance i.e users cannot withdraw more than they deposited
function removeEther(uint256 amount) external payable {
require(balances[msg.sender] >= amount, "cannot transfer amount greater than balance");
payable(msg.sender).transfer(amount);
balances[msg.sender] -= amount;
}
}
Test
Let’s run the test command:
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➜ BasicBankV2 git:(main) ✗ forge test -vvv
[⠊] Compiling...
[⠒] Compiling 19 files with Solc 0.8.25
[⠑] Solc 0.8.25 finished in 589.66ms
Compiler run successful!
Ran 2 tests for test/BasicBankV2.t.sol:BasicBankV2Test
[PASS] testAddEther() (gas: 37569)
[PASS] testRemoveEther() (gas: 33227)
Suite result: ok. 2 passed; 0 failed; 0 skipped; finished in 5.20ms (1.34ms CPU time)
Ran 1 test suite in 146.26ms (5.20ms CPU time): 2 tests passed, 0 failed, 0 skipped (2 total tests)
Great, we passed 2 test cases!
Reference: Solidity Exercise - Basic Bank V2
