feat: initializable delay module

contracts/DelayModule.sol

@@ -19,7 +19,7 @@ interface Executor {
 }
 
 contract DelayModule {
-
+  event DelayModuleSetup(address indexed initiator, address indexed safe);
   event TransactionAdded(
       uint indexed queueNonce,
       bytes32 indexed txHash,
@@ -32,7 +32,7 @@ contract DelayModule {
   event EnabledModule(address module);
   event DisabledModule(address module);
 
-  Executor public immutable executor;
+  Executor public executor;
   uint256 public txCooldown;
   uint256 public txExpiration;
   uint256 public txNonce;
@@ -44,17 +44,27 @@ contract DelayModule {
   // Mapping of approved modules
   mapping(address => bool) public modules;
 
+  bool public isInitialized = false;
+
+  constructor() {
+    isInitialized = true;
+  }
+
   /// @param _executor Address of the executor (e.g. a Safe)
   /// @param cooldown Cooldown in seconds that should be required after a transaction is proposed
   /// @param expiration Duration that a proposed transaction is valid for after the cooldown, in seconds (or 0 if valid forever)
   /// @notice There need to be at least 60 seconds between end of cooldown and expiration
-  constructor(Executor _executor, uint256 cooldown, uint256 expiration) {
+  function setUp(Executor _executor, uint256 cooldown, uint256 expiration) external {
+    require(!isInitialized, "Module is already initialized");
     require(cooldown > 0, "Cooldown must to be greater than 0");
     require(expiration == 0 || expiration >= 60 , "Expiratition must be 0 or at least 60 seconds");
     executor = _executor;
     txExpiration = expiration;
     txCooldown = cooldown;
-  }
+    isInitialized = true;
+
+    emit DelayModuleSetup(msg.sender, address(_executor));
+}
 
   modifier executorOnly() {
     require(msg.sender == address(executor), "Not authorized");

contracts/test/DelayModuleMock.sol

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: LGPL-3.0-only
+pragma solidity >=0.8.0;
+
+import "../DelayModule.sol";
+
+contract DelayModuleMock is DelayModule {
+    constructor() DelayModule() {
+        isInitialized = false;
+    }
+}

test/DelayModule.spec.ts

@@ -17,31 +17,35 @@ describe("DelayModule", async () => {
 
   const setupTestWithTestExecutor = deployments.createFixture(async () => {
     const base = await baseSetup();
-    const Module = await hre.ethers.getContractFactory("DelayModule");
-    const module = await Module.deploy(base.executor.address, 42, "0x1337");
+    const Module = await hre.ethers.getContractFactory("DelayModuleMock");
+    const module = await Module.deploy();
+    await module.setUp(base.executor.address, 42, "0x1337");
     return { ...base, Module, module };
   })
 
   const [user1] = waffle.provider.getWallets();
 
-  describe("constructor()", async () => {
+  describe("setUp()", async () => {
     it("throws if cooldown is 0", async () => {
-      const Module = await hre.ethers.getContractFactory("DelayModule")
+      const Module = await hre.ethers.getContractFactory("DelayModuleMock")
+      const module = await Module.deploy()
       await expect(
-          Module.deploy(user1.address, 0, 0)
+          module.setUp(user1.address, 0, 0)
       ).to.be.revertedWith("Cooldown must to be greater than 0")
     })
 
     it("throws if not enough time between txCooldown and txExpiration", async () => {
-      const Module = await hre.ethers.getContractFactory("DelayModule")
+      const Module = await hre.ethers.getContractFactory("DelayModuleMock")
+      const module = await Module.deploy()
       await expect(
-          Module.deploy(user1.address, 1, 59)
+          module.setUp(user1.address, 1, 59)
       ).to.be.revertedWith("Expiratition must be 0 or at least 60 seconds")
     })
 
     it("txExpiration can be 0", async () => {
-      const Module = await hre.ethers.getContractFactory("DelayModule")
-      await Module.deploy(user1.address, 1, 0)
+      const Module = await hre.ethers.getContractFactory("DelayModuleMock")
+      const module = await Module.deploy()
+      await module.setUp(user1.address, 1, 0)
     })
   })