Modifications to block minting for unit tests, in order to solve an NPE and give more options to callers.

This shouldn't affect the behaviour of existing tests, other than an NPE being replaced with an assertNotNull().

src/main/java/org/qortal/controller/BlockMinter.java

@@ -26,9 +26,6 @@ import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.transaction.TransactionData;
 import org.qortal.network.Network;
 import org.qortal.network.Peer;
-import org.qortal.network.message.BlockSummariesV2Message;
-import org.qortal.network.message.HeightV2Message;
-import org.qortal.network.message.Message;
 import org.qortal.repository.BlockRepository;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -38,6 +35,8 @@ import org.qortal.transaction.Transaction;
 import org.qortal.utils.Base58;
 import org.qortal.utils.NTP;
 
+import static org.junit.Assert.assertNotNull;
+
 // Minting new blocks
 
 public class BlockMinter extends Thread {
@@ -511,6 +510,21 @@ public class BlockMinter extends Thread {
 
 		PrivateKeyAccount mintingAccount = mintingAndOnlineAccounts[0];
 
+		Block block = mintTestingBlockRetainingTimestamps(repository, mintingAccount);
+		assertNotNull("Minted block must not be null", block);
+
+		return block;
+	}
+
+	public static Block mintTestingBlockUnvalidated(Repository repository, PrivateKeyAccount... mintingAndOnlineAccounts) throws DataException {
+		if (!BlockChain.getInstance().isTestChain())
+			throw new DataException("Ignoring attempt to mint testing block for non-test chain!");
+
+		// Ensure mintingAccount is 'online' so blocks can be minted
+		OnlineAccountsManager.getInstance().ensureTestingAccountsOnline(mintingAndOnlineAccounts);
+
+		PrivateKeyAccount mintingAccount = mintingAndOnlineAccounts[0];
+
 		return mintTestingBlockRetainingTimestamps(repository, mintingAccount);
 	}
 
@@ -518,6 +532,8 @@ public class BlockMinter extends Thread {
 		BlockData previousBlockData = repository.getBlockRepository().getLastBlock();
 
 		Block newBlock = Block.mint(repository, previousBlockData, mintingAccount);
+		if (newBlock == null)
+			return null;
 
 		// Make sure we're the only thread modifying the blockchain
 		ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();