interface Named {
    name string
}

struct NamedValue {
mut:
    name string
}

fn test_interface_cast_makes_detached_copy() {
    mut value := NamedValue{
        name: 'First'
    }
    face := Named(value)
    value.name = 'Second'
    assert face.name == 'First'
}

fn test_append_to_interface_array_makes_detached_copy() {
    mut value := NamedValue{
        name: 'First'
    }
    mut values := []Named{}
    values << value
    value.name = 'Second'
    assert values[0].name == 'First'
}

fn new_named_value() !NamedValue {
    return NamedValue{
        name: 'First'
    }
}

fn read_name(n Named) string {
    return n.name
}

fn test_auto_heap_interface_arg_keeps_value_fields() {
    value := new_named_value()!
    face := Named(value)
    assert read_name(value) == 'First'
    assert read_name(face) == 'First'
}