Datasource.groovy

environments {
  test {
    dataSource {
      pooled = true
      username = "yourUser"
      password = "yourPass"
      dbCreate = "create"
      url = "jdbc:postgresql://localhost:5432/test_db${System.properties.getProperty('test.suffix') ?: ''}"
      jndiName = null
    }     
  }
  // ...