Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1161#discussion_r178445472
--- Diff:
exec/java-exec/src/test/java/org/apache/drill/test/rowSet/test/TestHyperVectorReaders.java
---
@@ -0,0 +1,365 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.test.rowSet.test;
+
+import static org.apache.drill.test.rowSet.RowSetUtilities.mapArray;
+import static org.apache.drill.test.rowSet.RowSetUtilities.mapValue;
+import static org.apache.drill.test.rowSet.RowSetUtilities.strArray;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.apache.drill.common.types.TypeProtos.MinorType;
+import org.apache.drill.exec.record.metadata.TupleMetadata;
+import org.apache.drill.exec.record.selection.SelectionVector4;
+import org.apache.drill.test.SubOperatorTest;
+import org.apache.drill.test.rowSet.HyperRowSetImpl;
+import org.apache.drill.test.rowSet.RowSet.ExtendableRowSet;
+import org.apache.drill.test.rowSet.RowSet.HyperRowSet;
+import org.apache.drill.test.rowSet.RowSet.SingleRowSet;
+import org.apache.drill.test.rowSet.RowSetBuilder;
+import org.apache.drill.test.rowSet.RowSetReader;
+import org.apache.drill.test.rowSet.RowSetUtilities;
+import org.apache.drill.test.rowSet.RowSetWriter;
+import org.apache.drill.test.rowSet.schema.SchemaBuilder;
+import org.junit.Test;
+
+/**
+ * Test the reader mechanism that reads rows indexed via an SV4.
+ * SV4's introduce an additional level of indexing: each row may
+ * come from a different batch. The readers use the SV4 to find
+ * the root batch and vector, then must navigate downward from that
+ * vector for maps, repeated maps, lists, unions, repeated lists,
+ * nullable vectors and variable-length vectors.
+ * <p>
+ * This test does not cover repeated vectors; those tests should be added.
--- End diff --
[DRILL-6305](https://issues.apache.org/jira/browse/DRILL-6305)
---
