Implement UpdateAutoTimestampConverter (#298)

* Implement a JPA-based converter for UpdateAutoTimestamp, allowing us to persist instances of this class.

core/src/test/java/google/registry/persistence/UpdateAutoTimestampConverterTest.java

@@ -0,0 +1,102 @@
+// Copyright 2019 The Nomulus Authors. All Rights Reserved.
+//
+// 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 google.registry.persistence;
+
+import static com.google.common.truth.Truth.assertThat;
+import static google.registry.model.transaction.TransactionManagerFactory.jpaTm;
+
+import google.registry.model.ImmutableObject;
+import google.registry.model.UpdateAutoTimestamp;
+import google.registry.model.transaction.JpaTransactionManagerRule;
+import javax.persistence.Convert;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import org.hibernate.cfg.Environment;
+import org.junit.ClassRule;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+@RunWith(JUnit4.class)
+public class UpdateAutoTimestampConverterTest {
+
+  @ClassRule
+  public static PostgreSQLContainer postgres =
+      new PostgreSQLContainer()
+          .withDatabaseName("postgres")
+          .withUsername("postgres")
+          .withPassword("domain-registry");
+
+  @Rule
+  public final JpaTransactionManagerRule jpaTmRule =
+      new JpaTransactionManagerRule.Builder()
+          .withEntityClass(TestEntity.class)
+          .withProperty(Environment.HBM2DDL_AUTO, "update")
+          .build();
+
+  public UpdateAutoTimestampConverterTest() {}
+
+  @Test
+  public void testTypeConversion() {
+    TestEntity ent = new TestEntity("myinst", null);
+
+    jpaTm().transact(() -> jpaTm().getEntityManager().persist(ent));
+
+    TestEntity result =
+        jpaTm().transact(() -> jpaTm().getEntityManager().find(TestEntity.class, "myinst"));
+
+    assertThat(result.name).isEqualTo("myinst");
+    assertThat(result.uat.getTimestamp()).isEqualTo(jpaTmRule.getTxnClock().nowUtc());
+  }
+
+  @Test
+  public void testTimeChangesOnSubsequentTransactions() {
+    TestEntity ent1 = new TestEntity("myinst1", null);
+
+    jpaTm().transact(() -> jpaTm().getEntityManager().persist(ent1));
+
+    TestEntity result1 =
+        jpaTm().transact(() -> jpaTm().getEntityManager().find(TestEntity.class, "myinst1"));
+
+    jpaTmRule.getTxnClock().advanceOneMilli();
+
+    TestEntity ent2 = new TestEntity("myinst2", result1.uat);
+
+    jpaTm().transact(() -> jpaTm().getEntityManager().persist(ent2));
+
+    TestEntity result2 =
+        jpaTm().transact(() -> jpaTm().getEntityManager().find(TestEntity.class, "myinst2"));
+
+    assertThat(result1.uat.getTimestamp()).isNotEqualTo(result2.uat.getTimestamp());
+    assertThat(result2.uat.getTimestamp()).isEqualTo(jpaTmRule.getTxnClock().nowUtc());
+  }
+
+  @Entity(name = "TestEntity") // Override entity name to avoid the nested class reference.
+  public static class TestEntity extends ImmutableObject {
+
+    @Id String name;
+
+    @Convert(converter = UpdateAutoTimestampConverter.class)
+    UpdateAutoTimestamp uat;
+
+    public TestEntity() {}
+
+    public TestEntity(String name, UpdateAutoTimestamp uat) {
+      this.name = name;
+      this.uat = uat;
+    }
+  }
+}