How to limit query results (#5616)

* JPA/Hibernate
* Spring Data JPA

BAEL-2208

persistence-modules/spring-data-jpa/src/test/java/com/baeldung/limit/LimitIntegrationTest.java

@@ -0,0 +1,69 @@
+package com.baeldung.limit;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Sort;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+@DataJpaTest
+@RunWith(SpringRunner.class)
+public class LimitIntegrationTest {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+    @Autowired
+    private PassengerRepository repository;
+
+    @Before
+    public void before() {
+        entityManager.persist(Passenger.from("Jill", "Smith", 50));
+        entityManager.persist(Passenger.from("Eve", "Jackson", 95));
+        entityManager.persist(Passenger.from("Fred", "Bloggs", 22));
+        entityManager.persist(Passenger.from("Ricki", "Bobbie", 36));
+        entityManager.persist(Passenger.from("Siya", "Kolisi", 85));
+    }
+
+    @Test
+    public void givenSeveralPassengersWhenOrderedBySeatNumberLimitedToThenThePassengerInTheFirstFilledSeatIsReturned() {
+        Passenger expected = Passenger.from("Fred", "Bloggs", 22);
+
+        List<Passenger> passengers = repository.findOrderedBySeatNumberLimitedTo(1);
+
+        assertEquals(1, passengers.size());
+
+        Passenger actual = passengers.get(0);
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    public void givenSeveralPassengersWhenFindFirstByOrderBySeatNumberAscThenThePassengerInTheFirstFilledSeatIsReturned() {
+        Passenger expected = Passenger.from("Fred", "Bloggs", 22);
+
+        Passenger actual = repository.findFirstByOrderBySeatNumberAsc();
+
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    public void givenSeveralPassengersWhenFindPageSortedByThenThePassengerInTheFirstFilledSeatIsReturned() {
+        Passenger expected = Passenger.from("Fred", "Bloggs", 22);
+
+        Page<Passenger> page = repository.findAll(PageRequest.of(0, 1, Sort.by(Sort.Direction.ASC, "seatNumber")));
+
+        assertEquals(page.getContent().size(), 1);
+
+        Passenger actual = page.getContent().get(0);
+        assertEquals(expected, actual);
+    }
+}