DX-122953 Add empty split transfer coverage

Author: prashanthbdremio

vector/src/test/java/org/apache/arrow/vector/TestLargeListVector.java

@@ -992,6 +992,39 @@ public void testSplitAndTransferEmptyLargeListOffsetBuffer() {
     }
   }
 
+  @Test
+  public void testSplitAndTransferEmptyLargeListAllocatesOffsetBuffer() {
+    try (LargeListVector fromVector = LargeListVector.empty("fromVector", allocator);
+        LargeListVector toVector = LargeListVector.empty("toVector", allocator)) {
+      fromVector.addOrGetVector(FieldType.nullable(MinorType.INT.getType()));
+      fromVector.allocateNew();
+      fromVector.setValueCount(0);
+
+      TransferPair transferPair = fromVector.makeTransferPair(toVector);
+      transferPair.splitAndTransfer(0, 0);
+
+      assertAllocatedEmptyLargeListOffsetBuffer(toVector);
+    }
+  }
+
+  @Test
+  public void testSplitAndTransferEmptyNestedLargeListAllocatesOffsetBuffers() {
+    try (LargeListVector fromVector = LargeListVector.empty("fromVector", allocator);
+        LargeListVector toVector = LargeListVector.empty("toVector", allocator)) {
+      fromVector.addOrGetVector(FieldType.nullable(MinorType.LARGELIST.getType()));
+      LargeListVector childVector = (LargeListVector) fromVector.getDataVector();
+      childVector.addOrGetVector(FieldType.nullable(MinorType.INT.getType()));
+      fromVector.allocateNew();
+      fromVector.setValueCount(0);
+
+      TransferPair transferPair = fromVector.makeTransferPair(toVector);
+      transferPair.splitAndTransfer(0, 0);
+
+      assertAllocatedEmptyLargeListOffsetBuffer(toVector);
+      assertAllocatedEmptyLargeListOffsetBuffer((LargeListVector) toVector.getDataVector());
+    }
+  }
+
   private ArrowBuf assertEmptyLargeListOffsetBuffer(LargeListVector list) {
     List<ArrowBuf> buffers = list.getFieldBuffers();
     ArrowBuf offsetBuffer = buffers.get(1);
@@ -1001,6 +1034,12 @@ private ArrowBuf assertEmptyLargeListOffsetBuffer(LargeListVector list) {
     return offsetBuffer;
   }
 
+  private void assertAllocatedEmptyLargeListOffsetBuffer(LargeListVector list) {
+    ArrowBuf offsetBuffer = list.getOffsetBuffer();
+    assertTrue(offsetBuffer.capacity() >= LargeListVector.OFFSET_WIDTH);
+    assertEquals(0L, offsetBuffer.getLong(0));
+  }
+
   @Test
   public void testIsEmpty() {
     try (final LargeListVector vector = LargeListVector.empty("list", allocator)) {

vector/src/test/java/org/apache/arrow/vector/TestListVector.java

@@ -1172,6 +1172,39 @@ public void testSplitAndTransferEmptyListOffsetBuffer() {
     }
   }
 
+  @Test
+  public void testSplitAndTransferEmptyListAllocatesOffsetBuffer() {
+    try (ListVector fromVector = ListVector.empty("fromVector", allocator);
+        ListVector toVector = ListVector.empty("toVector", allocator)) {
+      fromVector.addOrGetVector(FieldType.nullable(MinorType.INT.getType()));
+      fromVector.allocateNew();
+      fromVector.setValueCount(0);
+
+      TransferPair transferPair = fromVector.makeTransferPair(toVector);
+      transferPair.splitAndTransfer(0, 0);
+
+      assertAllocatedEmptyListOffsetBuffer(toVector);
+    }
+  }
+
+  @Test
+  public void testSplitAndTransferEmptyNestedListAllocatesOffsetBuffers() {
+    try (ListVector fromVector = ListVector.empty("fromVector", allocator);
+        ListVector toVector = ListVector.empty("toVector", allocator)) {
+      fromVector.addOrGetVector(FieldType.nullable(MinorType.LIST.getType()));
+      ListVector childVector = (ListVector) fromVector.getDataVector();
+      childVector.addOrGetVector(FieldType.nullable(MinorType.INT.getType()));
+      fromVector.allocateNew();
+      fromVector.setValueCount(0);
+
+      TransferPair transferPair = fromVector.makeTransferPair(toVector);
+      transferPair.splitAndTransfer(0, 0);
+
+      assertAllocatedEmptyListOffsetBuffer(toVector);
+      assertAllocatedEmptyListOffsetBuffer((ListVector) toVector.getDataVector());
+    }
+  }
+
   private ArrowBuf assertEmptyListOffsetBuffer(ListVector list) {
     List<ArrowBuf> buffers = list.getFieldBuffers();
     ArrowBuf offsetBuffer = buffers.get(1);
@@ -1181,6 +1214,12 @@ private ArrowBuf assertEmptyListOffsetBuffer(ListVector list) {
     return offsetBuffer;
   }
 
+  private void assertAllocatedEmptyListOffsetBuffer(ListVector list) {
+    ArrowBuf offsetBuffer = list.getOffsetBuffer();
+    assertTrue(offsetBuffer.capacity() >= BaseRepeatedValueVector.OFFSET_WIDTH);
+    assertEquals(0, offsetBuffer.getInt(0));
+  }
+
   @Test
   public void testIsEmpty() {
     try (final ListVector vector = ListVector.empty("list", allocator)) {

vector/src/test/java/org/apache/arrow/vector/TestSplitAndTransfer.java

@@ -114,15 +114,16 @@ private void populateDenseUnionVector(final DenseUnionVector vector, int valueCo
   @Test
   public void testWithEmptyVector() {
     // MapVector use TransferImpl from ListVector
-    ListVector listVector = ListVector.empty("", allocator);
-    TransferPair transferPair = listVector.getTransferPair(allocator);
-    transferPair.splitAndTransfer(0, 0);
-    assertEquals(0, transferPair.getTo().getValueCount());
-    transferPair.getTo().clear();
-    listVector.clear();
+    try (ListVector listVector = ListVector.empty("", allocator)) {
+      TransferPair transferPair = listVector.getTransferPair(allocator);
+      try (ValueVector toVector = transferPair.getTo()) {
+        transferPair.splitAndTransfer(0, 0);
+        assertEquals(0, toVector.getValueCount());
+      }
+    }
     // BaseFixedWidthVector
     IntVector intVector = new IntVector("", allocator);
-    transferPair = intVector.getTransferPair(allocator);
+    TransferPair transferPair = intVector.getTransferPair(allocator);
     transferPair.splitAndTransfer(0, 0);
     assertEquals(0, transferPair.getTo().getValueCount());
     // BaseVariableWidthVector