### Question:
AwsRdsInstanceView { public String getDBInstanceIdentifier() { return databaseServer.getServerId(); } AwsRdsInstanceView(DatabaseServer databaseServer); Long getAllocatedStorage(); Integer getBackupRetentionPeriod(); String getDBInstanceClass(); String getDBInstanceIdentifier(); String getEngine(); String getEngineVersion(); String getMasterUsername(); String getMasterUserPassword(); String getMultiAZ(); String getStorageType(); List<String> getVPCSecurityGroups();  }### Answer:
@Test public void testDBInstanceIdentifier() { when(server.getServerId()).thenReturn("myserver"); assertEquals("myserver", underTest.getDBInstanceIdentifier()); }
@Test public void testNoDBInstanceIdentifier() { when(server.getServerId()).thenReturn(null); assertNull(underTest.getDBInstanceIdentifier()); }