convert CappedCrowdsale

contracts/crowdsale/validation/CappedCrowdsale.sol

 pragma solidity ^0.4.24;
 
+import "../../Initializable.sol";
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
@@ -8,16 +9,19 @@ import "../Crowdsale.sol";
  * @title CappedCrowdsale
  * @dev Crowdsale with a limit for total contributions.
  */
-contract CappedCrowdsale is Crowdsale {
+contract CappedCrowdsale is Initializable, Crowdsale {
   using SafeMath for uint256;
 
   uint256 private _cap;
 
+  constructor(uint256 cap) public {
+  }
+
   /**
    * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
    * @param cap Max amount of wei to be contributed
    */
-  constructor(uint256 cap) public {
+  function initialize(uint256 cap) public initializer {
     require(cap > 0);
     _cap = cap;
   }

contracts/mocks/CappedCrowdsaleImpl.sol

 pragma solidity ^0.4.24;
 
+import "../Initializable.sol";
 import "../token/ERC20/IERC20.sol";
 import "../crowdsale/validation/CappedCrowdsale.sol";
 
 
-contract CappedCrowdsaleImpl is CappedCrowdsale {
+contract CappedCrowdsaleImpl is Initializable, Crowdsale, CappedCrowdsale {
 
   constructor (
     uint256 rate,
@@ -16,6 +17,8 @@ contract CappedCrowdsaleImpl is CappedCrowdsale {
     Crowdsale(rate, wallet, token)
     CappedCrowdsale(cap)
   {
+    Crowdsale.initialize(rate, wallet, token);
+    CappedCrowdsale.initialize(cap);
   }
 
 }

test/crowdsale/CappedCrowdsale.test.js

@@ -9,7 +9,7 @@ require('chai')
   .should();
 
 const CappedCrowdsale = artifacts.require('CappedCrowdsaleImpl');
-const SimpleToken = artifacts.require('SimpleToken');
+const SimpleToken = artifacts.require('SimpleTokenMock');
 
 contract('CappedCrowdsale', function ([_, wallet]) {
   const rate = new BigNumber(1);