Fix tests with child contracts initializable

script/DeployChildContracts.s.sol

@@ -37,10 +37,8 @@ contract DeployChildContracts is Script {
             ""
         );
 
-        // TODO put behind proxy
         ChildAxelarBridgeAdaptor childBridgeAdaptorImplementation = new ChildAxelarBridgeAdaptor(
-            childGateway, // child gateway
-            address(childBridgeProxy) // child bridge
+            childGateway
         );
 
         // TODO confirm that we want the same proxyAdmin for both

script/InitializeChildContracts.s.sol

@@ -35,7 +35,7 @@ contract InitializeChildContracts is Script {
             address(childAxelarBridgeAdaptor), rootBridgeAdaptorString, childTokenTemplate, rootChainName, rootIMXToken
         );
 
-        childAxelarBridgeAdaptor.setRootBridgeAdaptor();
+        childAxelarBridgeAdaptor.initialize(address(childERC20Bridge));
 
         vm.stopBroadcast();
 

src/child/ChildAxelarBridgeAdaptor.sol

@@ -2,30 +2,29 @@
 pragma solidity ^0.8.21;
 
 import {AxelarExecutable} from "@axelar-gmp-sdk-solidity/contracts/executable/AxelarExecutable.sol";
+import {Initializable} from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
 import {IChildERC20Bridge} from "../interfaces/child/IChildERC20Bridge.sol";
 import {IChildAxelarBridgeAdaptorErrors} from "../interfaces/child/IChildAxelarBridgeAdaptor.sol";
 
-contract ChildAxelarBridgeAdaptor is AxelarExecutable, IChildAxelarBridgeAdaptorErrors {
+contract ChildAxelarBridgeAdaptor is AxelarExecutable, Initializable, IChildAxelarBridgeAdaptorErrors {
     /// @notice Address of bridge to relay messages to.
-    IChildERC20Bridge public immutable CHILD_BRIDGE;
+    IChildERC20Bridge public childBridge;
     string public rootBridgeAdaptor;
 
-    constructor(address _gateway, address _childBridge) AxelarExecutable(_gateway) {
+    constructor(address _gateway) AxelarExecutable(_gateway) {}
+
+    /**
+     * @notice Initializes the contract.
+     * @param _childBridge Address of the child bridge contract.
+     * @dev Always sets the rootBridgeAdaptor to whatever the rootERC20BridgeAdaptor of the bridge contract is.
+     */
+    function initialize(address _childBridge) external initializer {
         if (_childBridge == address(0)) {
             revert ZeroAddress();
         }
 
-        CHILD_BRIDGE = IChildERC20Bridge(_childBridge);
-    }
-
-    // TODO tests for this
-    // TODO does this need to be permissioned?
-    /**
-     * @notice Sets the root bridge adaptor address.
-     * @dev Always sets it to whatever the rootERC20BridgeAdaptor of the bridge contract is.
-     */
-    function setRootBridgeAdaptor() external {
-        rootBridgeAdaptor = CHILD_BRIDGE.rootERC20BridgeAdaptor();
+        childBridge = IChildERC20Bridge(_childBridge);
+        rootBridgeAdaptor = childBridge.rootERC20BridgeAdaptor();
     }
 
     /**
@@ -36,6 +35,6 @@ contract ChildAxelarBridgeAdaptor is AxelarExecutable, IChildAxelarBridgeAdaptor
         internal
         override
     {
-        CHILD_BRIDGE.onMessageReceive(sourceChain_, sourceAddress_, payload_);
+        childBridge.onMessageReceive(sourceChain_, sourceAddress_, payload_);
     }
 }

src/test/child/MockChildERC20Bridge.sol

@@ -3,4 +3,8 @@ pragma solidity ^0.8.21;
 
 contract MockChildERC20Bridge {
     function onMessageReceive(string calldata, string calldata, bytes calldata) external {}
+
+    function rootERC20BridgeAdaptor() external pure returns (string memory) {
+        return "rootERC20BridgeAdaptor";
+    }
 }

test/integration/child/ChildAxelarBridge.t.sol

@@ -33,7 +33,7 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
         childERC20Bridge = new ChildERC20Bridge();
         mockChildAxelarGateway = new MockChildAxelarGateway();
         childAxelarBridgeAdaptor =
-            new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway), address(childERC20Bridge));
+            new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway));
 
         childERC20Bridge.initialize(
             address(childAxelarBridgeAdaptor),
@@ -42,6 +42,8 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
             ROOT_CHAIN_NAME,
             IMX_TOKEN_ADDRESS
         );
+
+        childAxelarBridgeAdaptor.initialize(address(childERC20Bridge));
     }
 
     function test_ChildTokenMap() public {

test/unit/child/ChildAxelarBridgeAdaptor.t.sol

@@ -20,18 +20,19 @@ contract ChildAxelarBridgeAdaptorUnitTest is Test, IChildAxelarBridgeAdaptorErro
         mockChildERC20Bridge = new MockChildERC20Bridge();
         mockChildAxelarGateway = new MockChildAxelarGateway();
         childAxelarBridgeAdaptor =
-            new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway), address(mockChildERC20Bridge));
+            new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway));
+        childAxelarBridgeAdaptor.initialize(address(mockChildERC20Bridge));
     }
 
     function test_Constructor_SetsValues() public {
-        assertEq(address(childAxelarBridgeAdaptor.CHILD_BRIDGE()), address(mockChildERC20Bridge), "childBridge not set");
+        assertEq(address(childAxelarBridgeAdaptor.childBridge()), address(mockChildERC20Bridge), "childBridge not set");
         assertEq(address(childAxelarBridgeAdaptor.gateway()), address(mockChildAxelarGateway), "gateway not set");
     }
 
     function test_RevertIf_ConstructorGivenZeroAddress() public {
+        ChildAxelarBridgeAdaptor newAdaptor = new ChildAxelarBridgeAdaptor(GATEWAY_ADDRESS);
         vm.expectRevert(ZeroAddress.selector);
-        // Gateway address being zero is checked in Axelar's AxelarExecutable smart contract.
-        new ChildAxelarBridgeAdaptor(GATEWAY_ADDRESS, address(0));
+        newAdaptor.initialize(address(0));
     }
 
     function test_Execute() public {