add execute not supported

packages/contracts/src/Admin.sol

@@ -28,6 +28,9 @@ contract Admin is IMembership, PluginCloneable, ProposalUpgradeable {
     bytes32 public constant EXECUTE_PROPOSAL_PERMISSION_ID =
         keccak256("EXECUTE_PROPOSAL_PERMISSION");
 
+    /// @dev Thrown if the `execute` function is called.
+    error FunctionNotSupported();
+
     /// @notice Initializes the contract.
     /// @param _dao The associated DAO.
     /// @param _targetConfig Configuration for the execution target, specifying the target address and operation type
@@ -93,6 +96,19 @@ contract Admin is IMembership, PluginCloneable, ProposalUpgradeable {
         return true;
     }
 
+    /// @inheritdoc IProposal
+    function canExecute(uint256) public view virtual override returns (bool) {
+        return true;
+    }
+
+    /// @inheritdoc IProposal
+    /// @dev Note that this function will always revert since this contract doesn't store
+    ///      proposals and only executes the actions at run-time. This function is still
+    ///      necessary to allow compiling the contract as `Admin` inherits from `IProposal`.
+    function execute(uint256) public view virtual override {
+        revert FunctionNotSupported();
+    }
+
     /// @notice Creates and executes a new proposal.
     /// @param _metadata The metadata of the proposal.
     /// @param _actions The actions to be executed.

packages/contracts/test/10_unit-testing/11_plugin.ts

@@ -153,7 +153,18 @@ describe(PLUGIN_CONTRACT_NAME, function () {
     });
   });
 
-  describe('execute proposal: ', async () => {
+  describe('execute', async () => {
+    it('always reverts', async () => {
+      const {initializedPlugin: plugin} = await loadFixture(fixture);
+
+      await expect(plugin.execute(1)).to.be.revertedWithCustomError(
+        plugin,
+        'FunctionNotSupported'
+      );
+    });
+  });
+
+  describe('executeProposal: ', async () => {
     it('reverts when calling `execute()` if `EXECUTE_PROPOSAL_PERMISSION_ID` is not granted to the admin address', async () => {
       const {
         alice,