Increase unit test coverage for receiver

test/unit-tests/MultiBridgeMessageReceiver.t.sol

@@ -37,24 +37,58 @@ contract MultiBridgeMessageReceiverTest is Setup {
         timelockAddr = contractAddress[DST_CHAIN_ID]["TIMELOCK"];
     }
 
+    /// @dev verifies default setup
+    function test_constructor() public {
+        assertEq(receiver.srcChainId(), SRC_CHAIN_ID);
+        assertEq(address(receiver.gac()), contractAddress[DST_CHAIN_ID]["GAC"]);
+        assertEq(receiver.quorum(), 2);
+        assertTrue(receiver.isTrustedExecutor(wormholeAdapterAddr));
+        assertTrue(receiver.isTrustedExecutor(axelarAdapterAddr));
+    }
+
     /// @dev cannot be called with zero source chain id
     function test_constructor_zero_chain_id_input() public {
-        vm.expectRevert(Error.INVALID_SENDER_CHAIN_ID.selector);
-
         address[] memory receiverAdapters = new address[](1);
         receiverAdapters[0] = address(43);
 
+        vm.expectRevert(Error.INVALID_SENDER_CHAIN_ID.selector);
         new MultiBridgeMessageReceiver(0, address(42), receiverAdapters, 1);
     }
 
     /// @dev cannot be called with zero address GAC
     function test_constructor_zero_gac_address_input() public {
+        address[] memory receiverAdapters = new address[](1);
+        receiverAdapters[0] = address(43);
+
         vm.expectRevert(Error.ZERO_ADDRESS_INPUT.selector);
+        new MultiBridgeMessageReceiver(SRC_CHAIN_ID, address(0), receiverAdapters, 1);
+    }
 
+    /// @dev cannot be called with receiver adapters containing zero address
+    function test_constructor_zero_address_adapter() public {
         address[] memory receiverAdapters = new address[](1);
-        receiverAdapters[0] = address(43);
+        receiverAdapters[0] = address(0);
 
-        new MultiBridgeMessageReceiver(1, address(0), receiverAdapters, 1);
+        vm.expectRevert(Error.ZERO_ADDRESS_INPUT.selector);
+        new MultiBridgeMessageReceiver(SRC_CHAIN_ID, address(42), receiverAdapters, 1);
+    }
+
+    /// @dev cannot be called with zero quorum
+    function test_constructor_zero_quorum() public {
+        address[] memory receiverAdapters = new address[](1);
+        receiverAdapters[0] = address(42);
+
+        vm.expectRevert(Error.INVALID_QUORUM_THRESHOLD.selector);
+        new MultiBridgeMessageReceiver(SRC_CHAIN_ID, address(43), receiverAdapters, 0);
+    }
+
+    /// @dev cannot be called with quorum too large
+    function test_constructor_quorum_too_large() public {
+        address[] memory receiverAdapters = new address[](1);
+        receiverAdapters[0] = address(42);
+
+        vm.expectRevert(Error.INVALID_QUORUM_THRESHOLD.selector);
+        new MultiBridgeMessageReceiver(SRC_CHAIN_ID, address(43), receiverAdapters, 2);
     }
 
     /// @dev receives message from one adapter
@@ -330,6 +364,22 @@ contract MultiBridgeMessageReceiverTest is Setup {
         receiver.scheduleMessageExecution(msgId);
     }
 
+    /// @dev updates governance timelock
+    function test_update_governance_timelock() public {
+        vm.startPrank(timelockAddr);
+
+        receiver.updateGovernanceTimelock(address(42));
+        assertEq(receiver.governanceTimelock(), address(42));
+    }
+
+    /// @dev cannot update governance timelock with zero address
+    function test_update_governance_timelock_zero_address() public {
+        vm.startPrank(timelockAddr);
+
+        vm.expectRevert(Error.ZERO_GOVERNANCE_TIMELOCK.selector);
+        receiver.updateGovernanceTimelock(address(0));
+    }
+
     /// @dev adds one receiver adapter
     function test_update_receiver_adapter_add() public {
         vm.startPrank(timelockAddr);
@@ -391,6 +441,27 @@ contract MultiBridgeMessageReceiverTest is Setup {
         receiver.updateReceiverAdapters(adapters, operations);
     }
 
+    /// @dev cannot update with empty adapters list
+    function test_update_receiver_adapter_empty_lst() public {
+        vm.startPrank(timelockAddr);
+
+        vm.expectRevert(Error.ZERO_RECEIVER_ADAPTER.selector);
+
+        receiver.updateReceiverAdapters(new address[](0), new bool[](0));
+    }
+
+    /// @dev cannot update with zero adapter address
+    function test_update_receiver_adapter_zero_address() public {
+        vm.startPrank(timelockAddr);
+
+        address[] memory adapters = new address[](1);
+        adapters[0] = address(0);
+
+        vm.expectRevert(Error.ZERO_ADDRESS_INPUT.selector);
+
+        receiver.updateReceiverAdapters(adapters, new bool[](1));
+    }
+
     /// @dev cannot remove one receiver adapter without reducing quorum first
     function test_update_receiver_adapter_remove_invalid_quorum_threshold() public {
         vm.startPrank(timelockAddr);