Spring Boot Tests with H2 Database causing ClassCastException

Question

I'm getting this ClassCastException during testing one of my services:

java.lang.ClassCastException: class java.math.BigInteger cannot be cast to class java.lang.Integer (java.math.BigInteger and java.lang.Integer are in module java.base of loader 'bootstrap')

In that service there are multiple createNativeQuery-counts like this:

Query queryCount = em.createNativeQuery(sqlCount);
return (Integer)queryCount.getSingleResult();

When i fix the castexception to that:

return ((BigInteger)queryCount.getSingleResult()).intValue();

Then the tests are succesful but sadly iam getting an ClassCastException when i start the application and calling the service with the "real" Db2 Database. In that case BigInteger cannot be casted to Integer.

application-h2test.properties:

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.DB2Dialect

Config

@Configuration
@EnableTransactionManagement
public class SomethingConfig {
//...
   @Bean
    @Profile("h2test")
    @ConfigurationProperties(prefix = "spring.datasource")
    DataSource h2DataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl(
"jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE;MODE=DB2");
        dataSource.setUsername("sa");
        dataSource.setPassword("");

        return dataSource;
    }
//...
}

SomethingServiceTest

@ActiveProfiles("h2test")
@SpringBootTest
class SomethingServiceTest {

    @Autowired
    SomethingService sut;

    @Test
    void givenYWhenXThenZ() {
         this.sut.getSomething(); //In the Implementation the ClassCastException is thrown
    }
}

data.sql

SET MODE DB2;

I have tried several things, for example I have changed the dialect (DB2390,DB2400) and the mode in the application properties or the config.

The only solution i have currently in mind, is that i could catch the ClassCastException and when the Exception happens i will cast it to the Biginteger so that the test is successful.

However, I don't like to implement logic into a service that the test is succesful. Do you have another approach / idea ?

Answer 1

((Number)queryCount.getSingleResult()).intValue(); should do the job.