Add groupBy test for multiple multi-value dimensions. (#3415)

processing/src/test/java/io/druid/query/groupby/GroupByQueryRunnerTest.java

@@ -445,6 +445,40 @@ public class GroupByQueryRunnerTest
     TestHelper.assertExpectedObjects(expectedResults, results, "");
   }
 
+  @Test
+  public void testTwoMultiValueDimensions()
+  {
+    GroupByQuery query = GroupByQuery
+        .builder()
+        .setDataSource(QueryRunnerTestHelper.dataSource)
+        .setQuerySegmentSpec(QueryRunnerTestHelper.firstToThird)
+        .setDimFilter(new SelectorDimFilter("placementish", "a", null))
+        .setDimensions(
+            Lists.<DimensionSpec>newArrayList(
+                new DefaultDimensionSpec("placementish", "alias"),
+                new DefaultDimensionSpec("placementish", "alias2")
+            )
+        )
+        .setAggregatorSpecs(
+            Arrays.asList(
+                QueryRunnerTestHelper.rowsCount,
+                new LongSumAggregatorFactory("idx", "index")
+            )
+        )
+        .setGranularity(QueryRunnerTestHelper.allGran)
+        .build();
+
+    List<Row> expectedResults = Arrays.asList(
+        GroupByQueryRunnerTestHelper.createExpectedRow("2011-04-01", "alias", "a", "alias2", "a", "rows", 2L, "idx", 282L),
+        GroupByQueryRunnerTestHelper.createExpectedRow("2011-04-01", "alias", "a", "alias2", "preferred", "rows", 2L, "idx", 282L),
+        GroupByQueryRunnerTestHelper.createExpectedRow("2011-04-01", "alias", "preferred", "alias2", "a", "rows", 2L, "idx", 282L),
+        GroupByQueryRunnerTestHelper.createExpectedRow("2011-04-01", "alias", "preferred", "alias2", "preferred", "rows", 2L, "idx", 282L)
+    );
+
+    Iterable<Row> results = GroupByQueryRunnerTestHelper.runQuery(factory, runner, query);
+    TestHelper.assertExpectedObjects(expectedResults, results, "");
+  }
+
   @Test
   public void testMultipleDimensionsOneOfWhichIsMultiValue1()
   {