Increase coverage and add events rebalancer (#548)

## Motivation
Test coverage was horrible, this PR cleans up a lot of tech debt

contracts/gas-snapshots/rebalancer.gas-snapshot

@@ -7,16 +7,27 @@ OCR3Base_setOCR3Config:testSignerCannotBeZeroAddressReverts() (gas: 23717)
 OCR3Base_setOCR3Config:testTooManySignersReverts() (gas: 19838)
 OCR3Base_setOCR3Config:testTransmitterCannotBeZeroAddressReverts() (gas: 46567)
 OCR3Base_transmit:testConfigDigestMismatchReverts() (gas: 24788)
-OCR3Base_transmit:testForkedChainReverts() (gas: 46905)
+OCR3Base_transmit:testForkedChainReverts() (gas: 42804)
 OCR3Base_transmit:testNonIncreasingSequenceNumberReverts() (gas: 30480)
-OCR3Base_transmit:testNonUniqueSignatureReverts() (gas: 64488)
+OCR3Base_transmit:testNonUniqueSignatureReverts() (gas: 60396)
 OCR3Base_transmit:testSignatureOutOfRegistrationReverts() (gas: 26088)
-OCR3Base_transmit:testTransmit2SignersSuccess_gas() (gas: 56900)
+OCR3Base_transmit:testTransmit2SignersSuccess_gas() (gas: 56875)
 OCR3Base_transmit:testUnAuthorizedTransmitterReverts() (gas: 28578)
-OCR3Base_transmit:testUnauthorizedSignerReverts() (gas: 48820)
+OCR3Base_transmit:testUnauthorizedSignerReverts() (gas: 44719)
 OCR3Base_transmit:testWrongNumberOfSignaturesReverts() (gas: 25641)
+Rebalancer__report:test_EmptyReportReverts() (gas: 11135)
+Rebalancer_addLiquidity:test_addLiquiditySuccess() (gas: 249272)
 Rebalancer_rebalanceLiquidity:test_InsufficientLiquidityReverts() (gas: 19548)
 Rebalancer_rebalanceLiquidity:test_InvalidRemoteChainReverts() (gas: 162313)
-Rebalancer_rebalanceLiquidity:test_rebalanceBetweenPoolsSuccess() (gas: 7936550)
-Rebalancer_rebalanceLiquidity:test_rebalanceBetweenPoolsSuccess_AlreadyFinalized() (gas: 7522482)
-Rebalancer_rebalanceLiquidity:test_rebalanceLiquiditySuccess() (gas: 346467)
+Rebalancer_rebalanceLiquidity:test_rebalanceBetweenPoolsSuccess() (gas: 8095658)
+Rebalancer_rebalanceLiquidity:test_rebalanceBetweenPoolsSuccess_AlreadyFinalized() (gas: 7591176)
+Rebalancer_rebalanceLiquidity:test_rebalanceLiquiditySuccess() (gas: 348848)
+Rebalancer_removeLiquidity:test_InsufficientLiquidityReverts() (gas: 156472)
+Rebalancer_removeLiquidity:test_OnlyOwnerReverts() (gas: 10967)
+Rebalancer_removeLiquidity:test_removeLiquiditySuccess() (gas: 207747)
+Rebalancer_setCrossChainRebalancer:test_OnlyOwnerReverts() (gas: 17039)
+Rebalancer_setCrossChainRebalancer:test_ZeroAddressReverts() (gas: 21630)
+Rebalancer_setCrossChainRebalancer:test_ZeroChainSelectorReverts() (gas: 13102)
+Rebalancer_setCrossChainRebalancer:test_setCrossChainRebalancerSuccess() (gas: 157929)
+Rebalancer_setLocalLiquidityContainer:test_OnlyOwnerReverts() (gas: 10986)
+Rebalancer_setLocalLiquidityContainer:test_setLocalLiquidityContainerSuccess() (gas: 2887034)

contracts/src/v0.8/rebalancer/Rebalancer.sol

@@ -28,6 +28,7 @@ contract Rebalancer is IRebalancer, OCR3Base {
   error InvalidRemoteChain(uint64 chainSelector);
   error ZeroChainSelector();
   error InsufficientLiquidity(uint256 requested, uint256 available);
+  error EmptyReport();
 
   event LiquidityTransferred(
     uint64 indexed ocrSeqNum,
@@ -38,8 +39,16 @@ contract Rebalancer is IRebalancer, OCR3Base {
     bytes bridgeSpecificData,
     bytes bridgeReturnData
   );
-  event LiquidityAdded(address indexed provider, uint256 indexed amount);
-  event LiquidityRemoved(address indexed remover, uint256 indexed amount);
+  event LiquidityAddedToContainer(address indexed provider, uint256 indexed amount);
+  event LiquidityRemovedFromContainer(address indexed remover, uint256 indexed amount);
+  event LiquidityContainerSet(address indexed newLiquidityContainer);
+  event CrossChainRebalancerSet(
+    uint64 indexed remoteChainSelector,
+    IBridgeAdapter localBridge,
+    address remoteToken,
+    address remoteRebalancer,
+    bool enabled
+  );
 
   event FinalizationFailed(
     uint64 indexed ocrSeqNum,
@@ -55,7 +64,6 @@ contract Rebalancer is IRebalancer, OCR3Base {
     bool enabled;
   }
 
-  // solhint-disable-next-line chainlink-solidity/all-caps-constant-storage-variables
   string public constant override typeAndVersion = "Rebalancer 1.0.0-dev";
 
   /// @notice The token that this pool manages liquidity for.
@@ -111,7 +119,7 @@ contract Rebalancer is IRebalancer, OCR3Base {
     i_localToken.approve(address(s_localLiquidityContainer), amount);
     s_localLiquidityContainer.provideLiquidity(amount);
 
-    emit LiquidityAdded(msg.sender, amount);
+    emit LiquidityAddedToContainer(msg.sender, amount);
   }
 
   /// @notice Removes liquidity from the system and sends it to the caller, so the owner.
@@ -125,7 +133,7 @@ contract Rebalancer is IRebalancer, OCR3Base {
     s_localLiquidityContainer.withdrawLiquidity(amount);
     i_localToken.safeTransfer(msg.sender, amount);
 
-    emit LiquidityRemoved(msg.sender, amount);
+    emit LiquidityRemovedFromContainer(msg.sender, amount);
   }
 
   /// @notice Transfers liquidity to another chain.
@@ -210,7 +218,7 @@ contract Rebalancer is IRebalancer, OCR3Base {
     try
       remoteRebalancer.localBridge.finalizeWithdrawERC20(
         remoteRebalancer.remoteRebalancer, // remoteSender: the remote rebalancer
-        address(this), // localReceiver: us
+        address(this), // localReceiver: this contract
         bridgeSpecificPayload
       )
     {
@@ -243,6 +251,14 @@ contract Rebalancer is IRebalancer, OCR3Base {
     IRebalancer.LiquidityInstructions memory instructions = abi.decode(report, (IRebalancer.LiquidityInstructions));
 
     uint256 sendInstructions = instructions.sendLiquidityParams.length;
+    uint256 receiveInstructions = instructions.receiveLiquidityParams.length;
+
+    // There should always be instructions to send or receive, if not, the report is invalid
+    // and we revert to save the gas of the signature validation of OCR.
+    if (sendInstructions == 0 && receiveInstructions == 0) {
+      revert EmptyReport();
+    }
+
     for (uint256 i = 0; i < sendInstructions; ++i) {
       _rebalanceLiquidity(
         instructions.sendLiquidityParams[i].remoteChainSelector,
@@ -253,7 +269,6 @@ contract Rebalancer is IRebalancer, OCR3Base {
       );
     }
 
-    uint256 receiveInstructions = instructions.receiveLiquidityParams.length;
     for (uint256 i = 0; i < receiveInstructions; ++i) {
       _receiveLiquidity(
         instructions.receiveLiquidityParams[i].remoteChainSelector,
@@ -262,8 +277,6 @@ contract Rebalancer is IRebalancer, OCR3Base {
         ocrSeqNum
       );
     }
-
-    // todo emit?
   }
 
   // ================================================================
@@ -301,15 +314,19 @@ contract Rebalancer is IRebalancer, OCR3Base {
 
   /// @notice Sets a list of cross chain liquidity managers.
   /// @dev Will update the list of supported dest chains if the chain is new.
-  function setCrossChainRebalancer(CrossChainRebalancerArgs[] calldata crossChainRebalancers) external onlyOwner {
+  function setCrossChainRebalancers(CrossChainRebalancerArgs[] calldata crossChainRebalancers) external onlyOwner {
     for (uint256 i = 0; i < crossChainRebalancers.length; ++i) {
-      setCrossChainRebalancer(crossChainRebalancers[i]);
+      _setCrossChainRebalancer(crossChainRebalancers[i]);
     }
   }
 
+  function setCrossChainRebalancer(CrossChainRebalancerArgs calldata crossChainLiqManager) external onlyOwner {
+    _setCrossChainRebalancer(crossChainLiqManager);
+  }
+
   /// @notice Sets a single cross chain liquidity manager.
   /// @dev Will update the list of supported dest chains if the chain is new.
-  function setCrossChainRebalancer(CrossChainRebalancerArgs calldata crossChainLiqManager) public onlyOwner {
+  function _setCrossChainRebalancer(CrossChainRebalancerArgs calldata crossChainLiqManager) internal {
     if (crossChainLiqManager.remoteChainSelector == 0) {
       revert ZeroChainSelector();
     }
@@ -333,6 +350,14 @@ contract Rebalancer is IRebalancer, OCR3Base {
       remoteToken: crossChainLiqManager.remoteToken,
       enabled: crossChainLiqManager.enabled
     });
+
+    emit CrossChainRebalancerSet(
+      crossChainLiqManager.remoteChainSelector,
+      crossChainLiqManager.localBridge,
+      crossChainLiqManager.remoteToken,
+      crossChainLiqManager.remoteRebalancer,
+      crossChainLiqManager.enabled
+    );
   }
 
   /// @notice Gets the local liquidity container.
@@ -344,5 +369,7 @@ contract Rebalancer is IRebalancer, OCR3Base {
   /// @dev Only the owner can call this function.
   function setLocalLiquidityContainer(ILiquidityContainer localLiquidityContainer) external onlyOwner {
     s_localLiquidityContainer = localLiquidityContainer;
+
+    emit LiquidityContainerSet(address(localLiquidityContainer));
   }
 }