Add test for date_trunc

Author: vladmihalcea

core/src/test/java/com/vladmihalcea/book/hpjp/hibernate/query/function/DateTruncUtcFunctionTest.java

@@ -0,0 +1,120 @@
+package com.vladmihalcea.book.hpjp.hibernate.query.function;
+
+import com.vladmihalcea.book.hpjp.util.AbstractPostgreSQLIntegrationTest;
+import org.hibernate.boot.MetadataBuilder;
+import org.hibernate.boot.spi.MetadataBuilderContributor;
+import org.hibernate.dialect.function.SQLFunctionTemplate;
+import org.hibernate.dialect.function.StandardSQLFunction;
+import org.hibernate.type.StandardBasicTypes;
+import org.junit.Test;
+
+import javax.persistence.*;
+import java.sql.Timestamp;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.util.Properties;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Vlad Mihalcea
+ */
+public class DateTruncUtcFunctionTest extends AbstractPostgreSQLIntegrationTest {
+
+    @Override
+    protected Class<?>[] entities() {
+        return new Class<?>[]{
+                Post.class,
+        };
+    }
+
+    @Override
+    protected void additionalProperties(Properties properties) {
+        properties.put(
+                "hibernate.metadata_builder_contributor",
+                SqlFunctionsMetadataBuilderContributor.class
+        );
+    }
+
+    public static class SqlFunctionsMetadataBuilderContributor
+            implements MetadataBuilderContributor {
+
+        @Override
+        public void contribute(MetadataBuilder metadataBuilder) {
+            metadataBuilder.applySqlFunction(
+                    "date_trunc",
+                    new SQLFunctionTemplate(
+                            StandardBasicTypes.TIMESTAMP,
+                            "date_trunc('day', (?1 AT TIME ZONE 'UTC'))"
+                    )
+            );
+        }
+    }
+
+    @Override
+    public void afterInit() {
+        doInJPA(entityManager -> {
+
+            Post post = new Post();
+            post.setId(1L);
+            post.setTitle("High-Performance Java Persistence");
+            post.setCreatedOn(Timestamp.valueOf(LocalDateTime.of(2018, 11, 23, 11, 22, 33)));
+
+            entityManager.persist(post);
+        });
+    }
+
+    @Test
+    public void test() {
+        doInJPA(entityManager -> {
+            Tuple tuple = entityManager
+            .createQuery(
+                "select p.title as title, date_trunc(p.createdOn) as creation_date " +
+                "from Post p " +
+                "where p.id = :postId", Tuple.class)
+            .setParameter("postId", 1L)
+            .getSingleResult();
+
+            assertEquals("High-Performance Java Persistence", tuple.get("title"));
+            assertEquals(Timestamp.valueOf(LocalDateTime.of(2018, 11, 23, 0, 0, 0)), tuple.get("creation_date"));
+        });
+    }
+
+    @Entity(name = "Post")
+    @Table(name = "post")
+    public static class Post {
+
+        @Id
+        private Long id;
+
+        private String title;
+
+        @Column(name = "created_on")
+        private Timestamp createdOn;
+
+        public Long getId() {
+            return id;
+        }
+
+        public void setId(Long id) {
+            this.id = id;
+        }
+
+        public String getTitle() {
+            return title;
+        }
+
+        public void setTitle(String title) {
+            this.title = title;
+        }
+
+        public Timestamp getCreatedOn() {
+            return createdOn;
+        }
+
+        public void setCreatedOn(Timestamp createdOn) {
+            this.createdOn = createdOn;
+        }
+    }
+
+}