public void SetUp()
{
fixture = new FixtureGraph();
fixture.AddStructure("Hidden1", new Sentence());
fixture.AddStructure("Hidden2", new Sentence());
fixture.AddStructure("NotHidden3", new Sentence());
fixture.AddStructure("NotHidden4", new Sentence());
var constraints = new Policies();
constraints.HideGrammar("Hidden1");
constraints.HideGrammar("Hidden2");
fixture.Policies = constraints;
}