Added internal check methods.

contracts/crowdsale/Crowdsale.sol

@@ -141,6 +141,10 @@ contract Crowdsale is Initializable {
   // Internal interface (extensible)
   // -----------------------------------------
 
+  function _hasBeenInitialized() internal view returns (bool) {
+    return ((_rate > 0) && (_wallet != address(0)) && (_token != address(0)));
+  }
+
   /**
    * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use `super` in contracts that inherit from Crowdsale to extend their validations.
    * Example from CappedCrowdsale.sol's _preValidatePurchase method:

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -26,10 +26,8 @@ contract RefundableCrowdsale is Initializable, FinalizableCrowdsale {
    * @param goal Funding goal
    */
   function initialize(uint256 goal) public initializer {
-    // Make sure TimedCrowdsale.initialize (which FinalizableCrowdsale depends on) has been
-    // called before this initializer is executed
-    require(openingTime() > 0);
-    require(closingTime() > 0);
+    // FinalizableCrowdsale depends on TimedCrowdsale
+    assert(TimedCrowdsale._hasBeenInitialized());
 
     require(goal > 0);
 

contracts/crowdsale/emission/AllowanceCrowdsale.sol

@@ -22,10 +22,7 @@ contract AllowanceCrowdsale is Initializable, Crowdsale {
    * @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale
    */
   function initialize(address tokenWallet) public initializer {
-    // Make sure Crowdsale.initialize has been called before this initializer is executed
-    assert(rate() > 0);
-    assert(wallet() != address(0));
-    assert(token() != address(0));
+    assert(Crowdsale._hasBeenInitialized());
 
     require(tokenWallet != address(0));
     _tokenWallet = tokenWallet;

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -23,9 +23,7 @@ contract IncreasingPriceCrowdsale is Initializable, TimedCrowdsale {
    * @param finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
    */
   function initialize(uint256 initialRate, uint256 finalRate) public initializer {
-    // Make sure TimedCrowdsale.initialize has been called before this initializer is executed
-    require(openingTime() > 0);
-    require(closingTime() > 0);
+    assert(TimedCrowdsale._hasBeenInitialized());
 
     require(finalRate > 0);
     require(initialRate >= finalRate);

contracts/crowdsale/validation/CappedCrowdsale.sol

@@ -19,10 +19,7 @@ contract CappedCrowdsale is Initializable, Crowdsale {
    * @param cap Max amount of wei to be contributed
    */
   function initialize(uint256 cap) public initializer {
-    // Make sure Crowdsale.initialize has been called before this initializer is executed
-    assert(rate() > 0);
-    assert(wallet() != address(0));
-    assert(token() != address(0));
+    assert(Crowdsale._hasBeenInitialized());
 
     require(cap > 0);
     _cap = cap;

contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol

@@ -17,10 +17,7 @@ contract IndividuallyCappedCrowdsale is Initializable, Crowdsale, CapperRole {
   mapping(address => uint256) private _caps;
 
   function initialize(address sender) public initializer {
-    // Make sure Crowdsale.initialize has been called before this initializer is executed
-    assert(rate() > 0);
-    assert(wallet() != address(0));
-    assert(token() != address(0));
+    assert(Crowdsale._hasBeenInitialized());
 
     CapperRole.initialize(sender);
   }

contracts/crowdsale/validation/TimedCrowdsale.sol

@@ -29,10 +29,7 @@ contract TimedCrowdsale is Initializable, Crowdsale {
    * @param closingTime Crowdsale closing time
    */
   function initialize(uint256 openingTime, uint256 closingTime) public initializer {
-    // Make sure Crowdsale.initialize has been called before this initializer is executed
-    assert(rate() > 0);
-    assert(wallet() != address(0));
-    assert(token() != address(0));
+    assert(Crowdsale._hasBeenInitialized());
 
     // solium-disable-next-line security/no-block-members
     require(openingTime >= block.timestamp);
@@ -73,6 +70,10 @@ contract TimedCrowdsale is Initializable, Crowdsale {
     return block.timestamp > _closingTime;
   }
 
+  function _hasBeenInitialized() internal view returns (bool) {
+    return ((_openingTime > 0) && (_closingTime > 0));
+  }
+
   /**
    * @dev Extend parent behavior requiring to be within contributing period
    * @param beneficiary Token purchaser