How can we tell grails mongodb unit test to use a db?

I setup a db in mongodb called spotlight. To connect to that database, I use the following environment setup in DataSource.groovy:

grails {
    mongo {
        host = "localhost"
        port = 27017

    }
}


environments {
    development {   // MongoDB instance running without --auth flag.
        grails {
            mongo {
                databaseName = "spotlight"
            }
        }
    }
    test {
        grails {    // MongoDB instance running without --auth flag.
            mongo {
                databaseName = "spotlight"
            }
        }
    }

}

This is my unit test class:

@TestMixin(MongoDbTestMixin)
class BiographySpec extends Specification {

    def setup() {
    }

    def cleanup() {
    }

    void "given a bio then find() returns that bio object"() {


            given:
            mongoDomain([Biography])
            Biography bio = new Biography()

            def nameOf1stImage = "firstImage.png"
            def nameOf2ndImage = "secondImage.png"
            def nameInBio = "star"
            def descriptionOfBio = "a description"
            def id = 0;

            bio.firstImage = nameOf1stImage
            bio.secondImage = nameOf2ndImage
            bio.name = nameInBio
            bio.description = descriptionOfBio
            bio.images = [nameOf1stImage,nameOf2ndImage]

            when:
            bio.save(flush:true);
            id = bio.id

            then:
            Biography bioFromDb =  bio.get(id)
            bioFromDb.firstImage == nameOf1stImage
            bioFromDb.secondImage == nameOf2ndImage
            bioFromDb.name == nameInBio
            bioFromDb.description == descriptionOfBio
    }


}

I ran grails test-app, and grails created a biography document in test db, not spotlight db. Is there anything wrong with the way I configure environments setttings in DataSource.groovy ?

Thank you