DATAJDBC-252 - Make sure SimpleJdbcRepository.save(…) returns saved instance.

Previously, SimpleJdbcRepository.save(…) returned the original instance as result of the operation. That assumed that the JdbcAggregateOperations would only manipulate that instance, not return a new one. We now properly return the result of the delegating method call.

src/main/java/org/springframework/data/jdbc/repository/support/SimpleJdbcRepository.java

@@ -18,13 +18,13 @@ package org.springframework.data.jdbc.repository.support;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 import org.springframework.data.jdbc.core.JdbcAggregateOperations;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.util.Streamable;
 
 /**
  * @author Jens Schauder
@@ -42,10 +42,7 @@ public class SimpleJdbcRepository<T, ID> implements CrudRepository<T, ID> {
 	 */
 	@Override
 	public <S extends T> S save(S instance) {
-
-		entityOperations.save(instance);
-
-		return instance;
+		return entityOperations.save(instance);
 	}
 
 	/*
@@ -55,9 +52,9 @@ public class SimpleJdbcRepository<T, ID> implements CrudRepository<T, ID> {
 	@Override
 	public <S extends T> Iterable<S> saveAll(Iterable<S> entities) {
 
-		List<S> savedEntities = new ArrayList<>();
-		entities.forEach(e -> savedEntities.add(save(e)));
-		return savedEntities;
+		return Streamable.of(entities).stream() //
+				.map(this::save) //
+				.collect(Collectors.toList());
 	}
 
 	/*

src/test/java/org/springframework/data/jdbc/repository/support/SimpleJdbcRepositoryUnitTests.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018 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
+ *
+ *      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.springframework.data.jdbc.repository.support;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.springframework.data.jdbc.core.JdbcAggregateOperations;
+import org.springframework.data.relational.core.mapping.RelationalPersistentEntity;
+
+/**
+ * Unit tests for {@link SimpleJdbcRepository}.
+ * 
+ * @author Oliver Gierke
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class SimpleJdbcRepositoryUnitTests {
+
+	@Mock JdbcAggregateOperations operations;
+	@Mock RelationalPersistentEntity<Sample> entity;
+
+	@Test // DATAJDBC-252
+	public void saveReturnsEntityProducedByOperations() {
+
+		SimpleJdbcRepository<Sample, Object> repository = new SimpleJdbcRepository<>(operations, entity);
+
+		Sample expected = new Sample();
+		doReturn(expected).when(operations).save(any());
+
+		assertThat(repository.save(new Sample())).isEqualTo(expected);
+	}
+
+	static class Sample {}
+}