Added assertions to leaf initializers of (some) pseudo-abstract contracts.

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -26,6 +26,11 @@ 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);
+
     require(goal > 0);
 
     // conditional added to make initializer idempotent in case of diamond inheritance

contracts/crowdsale/emission/AllowanceCrowdsale.sol

@@ -22,6 +22,11 @@ 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));
+
     require(tokenWallet != address(0));
     _tokenWallet = tokenWallet;
   }

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -23,6 +23,10 @@ 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);
+
     require(finalRate > 0);
     require(initialRate >= finalRate);
     _initialRate = initialRate;

contracts/crowdsale/validation/CappedCrowdsale.sol

@@ -19,6 +19,11 @@ 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));
+
     require(cap > 0);
     _cap = cap;
   }

contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol

@@ -17,6 +17,11 @@ 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));
+
     CapperRole.initialize(sender);
   }
 

contracts/crowdsale/validation/TimedCrowdsale.sol

@@ -29,6 +29,11 @@ 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));
+
     // solium-disable-next-line security/no-block-members
     require(openingTime >= block.timestamp);
     require(closingTime >= openingTime);