replace _spendEncumbrance with _releaseEncumbrance (#26)

src/EncumberableToken.sol

@@ -104,7 +104,7 @@ contract EncumberableToken is ERC20, IERC20Permit, IERC7246 {
         if (amount > encumberedToTaker)  {
             uint256 excessAmount = amount - encumberedToTaker;
             // Exceeds Encumbrance, so spend all of it
-            _spendEncumbrance(src, msg.sender, encumberedToTaker);
+            _releaseEncumbrance(src, msg.sender, encumberedToTaker);
 
             // Having spent all the tokens encumbered to the mover,
             // We are now moving only "available" tokens and must check
@@ -114,24 +114,13 @@ contract EncumberableToken is ERC20, IERC20Permit, IERC7246 {
 
             _spendAllowance(src, msg.sender, excessAmount);
         } else {
-            _spendEncumbrance(src, msg.sender, amount);
+            _releaseEncumbrance(src, msg.sender, amount);
         }
 
         _transfer(src, dst, amount);
         return true;
     }
 
-    /**
-     * @dev Spend `amount` of `owner`'s encumbrance to `taker`
-     */
-    function _spendEncumbrance(address owner, address taker, uint256 amount) internal {
-        uint256 currentEncumbrance = encumbrances[owner][taker];
-        require(currentEncumbrance >= amount, "ERC7246: insufficient encumbrance");
-        uint256 newEncumbrance = currentEncumbrance - amount;
-        encumbrances[owner][taker] = newEncumbrance;
-        encumberedBalanceOf[owner] -= amount;
-    }
-
     /**
      * @notice Increases the amount of tokens that the caller has encumbered to
      * `taker` by `amount`
@@ -176,13 +165,13 @@ contract EncumberableToken is ERC20, IERC20Permit, IERC7246 {
      * @param amount Amount of tokens to decrease the encumbrance by
      */
     function release(address owner, uint256 amount) external {
-        _release(owner, msg.sender, amount);
+        _releaseEncumbrance(owner, msg.sender, amount);
     }
 
     /**
      * @dev Reduce `owner`'s encumbrance to `taker` by `amount`
      */
-    function _release(address owner, address taker, uint256 amount) private {
+    function _releaseEncumbrance(address owner, address taker, uint256 amount) private {
         require(encumbrances[owner][taker] >= amount, "ERC7246: insufficient encumbrance");
         encumbrances[owner][taker] -= amount;
         encumberedBalanceOf[owner] -= amount;

src/interfaces/IERC7246.sol

@@ -12,7 +12,7 @@ interface IERC7246 {
     event Encumber(address indexed owner, address indexed taker, uint256 amount);
 
     /**
-     * @dev Emitted when the encumbrance of a `taker` to an `owner` is reduced
+     * @dev Emitted when the encumbrance of an `owner` to a `taker` is reduced
      * by `amount`.
      */
     event Release(address indexed owner, address indexed taker, uint256 amount);
@@ -78,4 +78,4 @@ interface IERC7246 {
      * Trivially implemented as `balanceOf(owner) - encumberedBalanceOf(owner)`
      */
     function availableBalanceOf(address owner) external view returns (uint256);
-}
+}

test/EncumberableToken.t.sol

@@ -142,6 +142,8 @@ contract EncumberableTokenTest is Test {
 
         // bob calls transfers from alice to charlie
         vm.prank(bob);
+        vm.expectEmit(true, true, true, true);
+        emit Release(alice, bob, 40e18);
         wrappedToken.transferFrom(alice, charlie, 40e18);
 
         // alice balance is reduced
@@ -175,6 +177,8 @@ contract EncumberableTokenTest is Test {
 
         // bob calls transfers from alice to charlie
         vm.prank(bob);
+        vm.expectEmit(true, true, true, true);
+        emit Release(alice, bob, 20e18);
         wrappedToken.transferFrom(alice, charlie, 40e18);
 
         // alice balance is reduced