Unable to startup Hibernate

I'm trying to write some integration tests on some legacy code. When I run the test it complains with those errors.

org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:267) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:231) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:240) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:210) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]

.....

Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:257) ~[hibernate-core-5.2.3.Final.jar:5.2.3.Final]
    ... 52 common frames omitted

I cannot get whats going on. Probably the hibernate.cfg.xml is not loaded, but no matter where I put it in /src/test/resources or /src/test/java it will not change. Using hibernate 5.23. What is this about? There is something going on between 4 and 5 version in hibernate. Something with the need to call StandardServiceRegistryBuilder().applySettings(...). The code executed throught main looks running okay. Any hints???