convert IncreasingPriceCrowdsale to initializers

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

 pragma solidity ^0.4.24;
 
+import "../../Initializable.sol";
 import "../validation/TimedCrowdsale.sol";
 import "../../math/SafeMath.sol";
 
@@ -10,18 +11,21 @@ import "../../math/SafeMath.sol";
  * Note that what should be provided to the constructor is the initial and final _rates_, that is,
  * the amount of tokens per wei contributed. Thus, the initial rate must be greater than the final rate.
  */
-contract IncreasingPriceCrowdsale is TimedCrowdsale {
+contract IncreasingPriceCrowdsale is Initializable, TimedCrowdsale {
   using SafeMath for uint256;
 
   uint256 private _initialRate;
   uint256 private _finalRate;
 
+  constructor(uint256 initialRate, uint256 finalRate) public {
+  }
+
   /**
    * @dev Constructor, takes initial and final rates of tokens received per wei contributed.
    * @param initialRate Number of tokens a buyer gets per wei at the start of the crowdsale
    * @param finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
    */
-  constructor(uint256 initialRate, uint256 finalRate) public {
+  function initialize(uint256 initialRate, uint256 finalRate) public initializer {
     require(finalRate > 0);
     require(initialRate >= finalRate);
     _initialRate = initialRate;

contracts/mocks/IncreasingPriceCrowdsaleImpl.sol

 pragma solidity ^0.4.24;
 
+import "../Initializable.sol";
 import "../crowdsale/price/IncreasingPriceCrowdsale.sol";
 import "../math/SafeMath.sol";
 
 
-contract IncreasingPriceCrowdsaleImpl is IncreasingPriceCrowdsale {
+contract IncreasingPriceCrowdsaleImpl is Initializable, IncreasingPriceCrowdsale {
 
   constructor (
     uint256 openingTime,
@@ -19,6 +20,9 @@ contract IncreasingPriceCrowdsaleImpl is IncreasingPriceCrowdsale {
     TimedCrowdsale(openingTime, closingTime)
     IncreasingPriceCrowdsale(initialRate, finalRate)
   {
+    Crowdsale.initialize(initialRate, wallet, token);
+    TimedCrowdsale.initialize(openingTime, closingTime);
+    IncreasingPriceCrowdsale.initialize(initialRate, finalRate);
   }
 
 }

test/crowdsale/IncreasingPriceCrowdsale.test.js

@@ -11,7 +11,7 @@ require('chai')
   .should();
 
 const IncreasingPriceCrowdsale = artifacts.require('IncreasingPriceCrowdsaleImpl');
-const SimpleToken = artifacts.require('SimpleToken');
+const SimpleToken = artifacts.require('SimpleTokenMock');
 
 contract('IncreasingPriceCrowdsale', function ([_, investor, wallet, purchaser]) {
   const value = ether(1);