returnInstanceForEmptyRow should work for constructor auto-mapping

fixes mybatis#2665

Author: harawata

src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java

@@ -750,7 +750,9 @@ private Object applyConstructorAutomapping(ResultSetWrapper rsw, ResultMap resul
       foundValues = applyColumnOrderBasedConstructorAutomapping(rsw, constructorArgTypes, constructorArgs, constructor,
           foundValues);
     }
-    return foundValues ? objectFactory.create(resultType, constructorArgTypes, constructorArgs) : null;
+    return foundValues || configuration.isReturnInstanceForEmptyRow()
+        ? objectFactory.create(resultType, constructorArgTypes, constructorArgs)
+        : null;
   }
 
   private boolean applyColumnOrderBasedConstructorAutomapping(ResultSetWrapper rsw, List<Class<?>> constructorArgTypes,

src/test/java/org/apache/ibatis/submitted/empty_row/ImmutableParent.java

@@ -0,0 +1,35 @@
+/*
+ *    Copyright 2009-2022 the original author or authors.
+ *
+ *    Licensed 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
+ *
+ *       https://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.ibatis.submitted.empty_row;
+
+public class ImmutableParent {
+  private final String col1;
+  private final String col2;
+
+  public ImmutableParent(String col1, String col2) {
+    super();
+    this.col1 = col1;
+    this.col2 = col2;
+  }
+
+  public String getCol1() {
+    return col1;
+  }
+
+  public String getCol2() {
+    return col2;
+  }
+}

src/test/java/org/apache/ibatis/submitted/empty_row/Mapper.java

@@ -56,4 +56,7 @@ public interface Mapper {
       "left join child c on c.parent_id = p.id",
       "left join pet e on e.parent_id = p.id", "where p.id = #{id}" })
   Parent getTwoCollections(Integer id);
+
+  @Select("select col1, col2 from parent where id = #{id}")
+  ImmutableParent selectImmutable(Integer id);
 }

src/test/java/org/apache/ibatis/submitted/empty_row/ReturnInstanceForEmptyRowTest.java

@@ -139,4 +139,23 @@ void shouldSquashMultipleEmptyResults() {
       assertNotNull(parent.getPets().get(0));
     }
   }
+
+  @Test
+  void testConstructorAutomapping() {
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      ImmutableParent parent = mapper.selectImmutable(1);
+      assertNotNull(parent);
+    }
+  }
+
+  @Test
+  void testArgNameBasedConstructorAutomapping() {
+    sqlSessionFactory.getConfiguration().setArgNameBasedConstructorAutoMapping(true);
+    try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+      Mapper mapper = sqlSession.getMapper(Mapper.class);
+      ImmutableParent parent = mapper.selectImmutable(1);
+      assertNotNull(parent);
+    }
+  }
 }