interface Speaker {
    speak() string
}

union MyUnion implements Speaker {
    vint    int
    vu32    u32
    vstring string
}

fn (u MyUnion) speak() string {
    return 'hi, u.vint: ${unsafe { u.vint }}'
}

fn test_union_implementing_interface() {
    s := Speaker(MyUnion{
        vint: 123
    })
    assert s.speak() == 'hi, u.vint: 123'
}

interface Any {}

struct Thing {}

union Bad {
    f f64
    a Any
}

union BadBits {
    f   f64
    bad Bad
}

fn bad_from_float(x f64) Bad {
    bits := BadBits{
        f: x
    }
    return unsafe { bits.bad }
}

fn test_union_str_with_invalid_interface_member_does_not_crash() {
    x := [bad_from_float(2.0)]
    assert x.str() == '[Bad{\n    f: 2.0\n    a: unknown interface value\n}]'
}

fn test_union_str_with_valid_interface_member_still_works() {
    x := Bad{
        a: Thing{}
    }
    assert x.str().contains('a: Any(Thing{})')
}