What causes java.lang.IllegalStateException: Failed to load ApplicationContext error? I am new to spring boot, so I don't understand what caused the error mentioned above here since everything gives no warnings and is imported from official libraries import org.junit.jupiter.api.Assertions import org.junit.jupiter.api.Test import org.springframework.beans.factory.annotation.Autowired import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager import javax.sql.DataSource @DataJpaTest...