BAEL-1412 add java 8 spring data features (#3306)

spring-boot/src/main/java/org/baeldung/repository/UserRepository.java

@@ -2,9 +2,23 @@ package org.baeldung.repository;
 
 import org.baeldung.model.User;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Repository;
 
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Stream;
+
 @Repository("userRepository")
 public interface UserRepository extends JpaRepository<User, Integer> {
-    public int countByStatus(int status);
+
+    int countByStatus(int status);
+
+    Optional<User> findOneByName(String name);
+
+    Stream<User> findAllByName(String name);
+
+    @Async
+    CompletableFuture<User> findOneByStatus(Integer status);
+
 }

spring-boot/src/test/java/org/baeldung/repository/UserRepositoryTest.java

@@ -0,0 +1,97 @@
+package org.baeldung.repository;
+
+import org.baeldung.boot.Application;
+import org.baeldung.model.User;
+import org.junit.After;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.stream.Stream;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+/**
+ * Created by adam.
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = Application.class)
+public class UserRepositoryTest {
+
+    private final String USER_NAME_ADAM = "Adam";
+    private final Integer ACTIVE_STATUS = 1;
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Test
+    public void shouldReturnEmptyOptionalWhenSearchByNameInEmptyDB() {
+        Optional<User> foundUser = userRepository.findOneByName(USER_NAME_ADAM);
+
+        assertThat(foundUser.isPresent(), equalTo(false));
+    }
+
+    @Test
+    public void shouldReturnOptionalWithPresentUserWhenExistsWithGivenName() {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        userRepository.save(user);
+
+        Optional<User> foundUser = userRepository.findOneByName(USER_NAME_ADAM);
+
+        assertThat(foundUser.isPresent(), equalTo(true));
+        assertThat(foundUser.get()
+            .getName(), equalTo(USER_NAME_ADAM));
+    }
+
+    @Test
+    @Transactional
+    public void shouldReturnStreamOfUsersWithNameWhenExistWithSameGivenName() {
+        User user1 = new User();
+        user1.setName(USER_NAME_ADAM);
+        userRepository.save(user1);
+
+        User user2 = new User();
+        user2.setName(USER_NAME_ADAM);
+        userRepository.save(user2);
+
+        User user3 = new User();
+        user3.setName(USER_NAME_ADAM);
+        userRepository.save(user3);
+
+        User user4 = new User();
+        user4.setName("SAMPLE");
+        userRepository.save(user4);
+
+        try (Stream<User> foundUsersStream = userRepository.findAllByName(USER_NAME_ADAM)) {
+            assertThat(foundUsersStream.count(), equalTo(3l));
+        }
+    }
+
+    @Test
+    public void shouldReturnUserWithGivenStatusAsync() throws ExecutionException, InterruptedException {
+        User user = new User();
+        user.setName(USER_NAME_ADAM);
+        user.setStatus(ACTIVE_STATUS);
+        userRepository.save(user);
+
+        CompletableFuture<User> userByStatus = userRepository.findOneByStatus(ACTIVE_STATUS);
+
+        assertThat(userByStatus.get()
+            .getName(), equalTo(USER_NAME_ADAM));
+
+    }
+
+    @After
+    public void cleanUp() {
+        userRepository.deleteAll();
+    }
+
+}