Add test for IS NOT NULL filter on join column in left join (#11636)

sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java

@@ -18252,6 +18252,50 @@ public class CalciteQueryTest extends BaseCalciteQueryTest
     );
   }
 
+  @Test
+  @Parameters(source = QueryContextForJoinProvider.class)
+  public void testLeftJoinWithNotNullFilter(Map<String, Object> queryContext) throws Exception
+  {
+    testQuery(
+        "SELECT s.dim1, t.dim1\n"
+        + "FROM foo as s\n"
+        + "LEFT JOIN foo as t "
+        + "ON s.dim1 = t.dim1 "
+        + "and s.dim1 IS NOT NULL\n",
+        queryContext,
+        ImmutableList.of(
+            newScanQueryBuilder()
+                .dataSource(
+                    join(
+                        new TableDataSource(CalciteTests.DATASOURCE1),
+                        new QueryDataSource(newScanQueryBuilder()
+                            .dataSource(CalciteTests.DATASOURCE1)
+                            .intervals(querySegmentSpec(Filtration.eternity()))
+                            .columns(ImmutableList.of("dim1"))
+                            .resultFormat(ScanQuery.ResultFormat.RESULT_FORMAT_COMPACTED_LIST)
+                            .context(QUERY_CONTEXT_DEFAULT)
+                            .build()),
+                        "j0.",
+                        equalsCondition(DruidExpression.fromColumn("dim1"), DruidExpression.fromColumn("j0.dim1")),
+                        JoinType.LEFT
+                    )
+                )
+                .intervals(querySegmentSpec(Filtration.eternity()))
+                .columns("dim1", "j0.dim1")
+                .context(queryContext)
+                .build()
+        ),
+        ImmutableList.of(
+            new Object[]{"", ""},
+            new Object[]{"10.1", "10.1"},
+            new Object[]{"2", "2"},
+            new Object[]{"1", "1"},
+            new Object[]{"def", "def"},
+            new Object[]{"abc", "abc"}
+        )
+    );
+  }
+
   @Test
   @Parameters(source = QueryContextForJoinProvider.class)
   public void testInnerJoinSubqueryWithSelectorFilter(Map<String, Object> queryContext) throws Exception