move method only used in tests to the tests

block-storage/src/test/java/org/lucares/pdb/diskstorage/DiskStorageTest.java

@@ -46,7 +46,7 @@ public class DiskStorageTest {
 		try (DiskStorage ds = new DiskStorage(databaseFile)) {
 			final int numBlocks = 10;
 
-			ds.allocateBlocks(numBlocks, BLOCK_SIZE);
+			allocateBlocks(ds, numBlocks, BLOCK_SIZE);
 			final List<DiskBlock> blocks = new ArrayList<>();
 
 			// fill the first 16 512-byte blocks
@@ -101,7 +101,7 @@ public class DiskStorageTest {
 		try (DiskStorage ds = new DiskStorage(databaseFile)) {
 			final int numBlocks = 10;
 
-			final long[] blockOffsets = ds.allocateBlocks(numBlocks, BLOCK_SIZE);
+			final long[] blockOffsets = allocateBlocks(ds, numBlocks, BLOCK_SIZE);
 
 			for (final long blockOffset : blockOffsets) {
 
@@ -292,4 +292,15 @@ public class DiskStorageTest {
 			buffer[i] = val;
 		}
 	}
+
+	private long[] allocateBlocks(final DiskStorage ds, final int numNewBlocks, final int blockSize)
+			throws IOException {
+
+		final long[] result = new long[numNewBlocks];
+		for (int i = 0; i < numNewBlocks; i++) {
+			final long blockOffset = ds.allocateBlock(blockSize);
+			result[i] = blockOffset;
+		}
+		return result;
+	}
 }