upgrade compiler to 0.8.30 and remove deprecated mocks

- Updated all source and test contracts to Solidity 0.8.30
- Removed outdated  diagram and redundant
- Introduced  for better internal state testing
- Enhanced  constructor with native token validation
- Added  library integration in
- Expanded unit tests with  coverage (exchange rate, utilization, borrow index)
- Improved Makefile to use updated bulloak scaffold command with 0.8.30

Author: ademolahh

Makefile

@@ -6,7 +6,7 @@ gen:
 	@find test/unit -type f -name "*.tree" \
 		! -size 0c \
 		! -exec test -f "$$(dirname "{}")/$$(basename "{}" .tree).t.sol" \; \
-		-exec sh -c 'if grep -q "[A-Za-z]" "$$1"; then bulloak scaffold -S -w -s 0.8.28 "$$1"; fi' _ {} \;
+		-exec sh -c 'if grep -q "[A-Za-z]" "$$1"; then bulloak scaffold -S -w -s 0.8.30 "$$1"; fi' _ {} \;
 
 check:
 	@python3 convert_trees.py test/unit

images/contract-interaction.png

@@ -31,3 +31,4 @@ graph TD
     AM --> AN[Borrower Redeems Collateral]
     AN --> AO[Exit]
     AL -->|Continue Borrowing| AG
+

design.mmd images/design.mmddesign.mmd renamed to images/design.mmd

@@ -1,2 +1,4 @@
 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.28;
+pragma solidity 0.8.30;
+
+contract CollateralManager { }

images/user-interaction.png

@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.30;
+
+contract LiquidationManager { }

src/CollateralManager.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.28;
+pragma solidity 0.8.30;
 
 import { IZToken, ZToken } from "./ZToken.sol";
 

src/LiquidationManger.sol

@@ -1,10 +1,14 @@
 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.28;
+pragma solidity 0.8.30;
 
 import { IZToken, ZToken } from "./ZToken.sol";
 
 contract ZNative is ZToken {
-    constructor(IZToken.MarketConfig memory _config) ZToken(_config) { }
+    address private constant NATIVE_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
+
+    constructor(IZToken.MarketConfig memory _config) ZToken(_config) {
+        if (_config.underlyingToken != NATIVE_TOKEN_ADDRESS) revert();
+    }
 
     function name() public view override returns (string memory) { }
 

src/ZErc20.sol

@@ -1,31 +1,33 @@
 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.28;
+pragma solidity 0.8.30;
 
 import { ERC20 } from "solady/tokens/ERC20.sol";
 import { IZToken } from "./interfaces/IZToken.sol";
 import { FixedPointMathLib } from "solady/utils/FixedPointMathLib.sol";
+import { InterestMath } from "./libraries/InterestMath.sol";
 
 abstract contract ZToken is IZToken, ERC20 {
     using FixedPointMathLib for uint256;
+    using InterestMath for uint256;
 
-    uint256 private totalCash;
-    uint256 private totalBorrow;
-    uint256 private totalReserve;
-    uint256 private borrowIndex;
+    uint256 internal totalBorrow;
+    uint256 internal totalReserve;
+    uint256 internal borrowIndex;
 
-    address private immutable UNDERLYING_TOKEN;
+    address public immutable UNDERLYING_TOKEN;
 
-    uint256 private immutable UTILIZATION_THRESHOLD;
-    uint256 private immutable SLOPE_BEFORE_KINK;
-    uint256 private immutable SLOPE_AFTER_KINK;
-    uint256 private immutable BASE_BORROW_RATE;
-    uint256 private immutable RESERVE_FACTOR;
-    uint256 private immutable COLLATERAL_FACTOR;
+    uint256 public immutable UTILIZATION_THRESHOLD;
+    uint256 public immutable SLOPE_BEFORE_KINK;
+    uint256 public immutable SLOPE_AFTER_KINK;
+    uint256 public immutable BASE_BORROW_RATE;
+    uint256 public immutable RESERVE_FACTOR;
+    uint256 public immutable COLLATERAL_FACTOR;
 
-    uint256 private constant SECONDS_PER_YEAR = 365 days;
+    uint256 public constant SECONDS_PER_YEAR = 365 days;
+    uint256 public constant INITIAL_EXCHANGE_RATE = 0.02e18;
 
-    mapping(address user => uint256 index) private userBorrowIndex;
-    mapping(address user => uint256 amount) private collateralAmount;
+    mapping(address user => uint256 index) public userBorrowIndex;
+    mapping(address user => uint256 amount) public collateralAmount;
 
     constructor(MarketConfig memory _config) {
         UNDERLYING_TOKEN = _config.underlyingToken;
@@ -39,45 +41,12 @@ abstract contract ZToken is IZToken, ERC20 {
         borrowIndex = 1e18;
     }
 
-    function _mint(uint256 _zTokenAmount) internal returns (uint256) { }
+    function _getCash() internal view virtual returns (uint256) { }
 
-    function _getUtilization() internal pure returns (uint256) { }
+    function getExchangeRate() external view returns (uint256) {
+        uint256 cash = _getCash();
+        if (cash == 0) return INITIAL_EXCHANGE_RATE;
 
-    function getTotalCash() external view returns (uint256) {
-        return totalCash;
-    }
-
-    function getReserves() external view returns (uint256) {
-        return totalReserve;
-    }
-
-    function getExchangeRate() external view returns (uint256) { }
-
-    function getUnderlyingToken() external view returns (address) {
-        return UNDERLYING_TOKEN;
-    }
-
-    function utilizationThreshold() external view returns (uint256) {
-        return UTILIZATION_THRESHOLD;
-    }
-
-    function slopeBeforeKink() external view returns (uint256) {
-        return SLOPE_BEFORE_KINK;
-    }
-
-    function slopeAfterKink() external view returns (uint256) {
-        return SLOPE_AFTER_KINK;
-    }
-
-    function baseBorrowRate() external view returns (uint256) {
-        return BASE_BORROW_RATE;
-    }
-
-    function reserveFactor() external view returns (uint256) {
-        return RESERVE_FACTOR;
-    }
-
-    function collateralFactor() external view returns (uint256) {
-        return COLLATERAL_FACTOR;
+        return cash.getExchangeRate(totalBorrow, totalReserve, totalSupply());
     }
 }

src/ZNative.sol

@@ -1,4 +1,4 @@
 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.28;
+pragma solidity 0.8.30;
 
 contract ZTokenFactory { }