Testing constraints in Grails version 2.1.1 vs version 2.1.2

MembreTests.groovy

void testConstraints() {
//...
Membre toto = new Membre()

// in version 2.1.2 or sup

assert !toto.validate()
assert "nullable" == toto.errors["prenom"].code
assert "nullable" == toto.errors["nom"].code

// in version 2.1.1 
assert !toto.validate()
assert "nullable" == toto.errors["prenom"]
assert "nullable" == toto.errors["nom"]

//...
}