public void given_invalid_children_when_validating_parent_should_return_validation_results()
{
var parent = new Parent
{
Address = new Address{},
Car = new Car(),
Children = new List<Child> {new Child {FirstName = "Todd"}, new Child {LastName = "Meinershagen"}}
};
var results = new List<ValidationResult>();
parent.TryValidate(results);
results.Should()
.Contain(r => r.ErrorMessage == "Child requires a first name.")
.And
.Contain(r => r.ErrorMessage == "Child requires a last name.")
.And
.Contain(r => r.ErrorMessage == "Address requires a city.")
.And
.Contain(r => r.ErrorMessage == "Car requires a make.")
.And
.Contain(r => r.ErrorMessage == "Car requires a model.");
}