import strconv

fn value(n int) int {
    return n
}

struct Foo {
    n int
}

fn (foo Foo) value() int {
    return foo.n
}

fn test_negative() {
    one := 1
    negative_one := -1
    assert -one == negative_one
    assert one == -negative_one

    assert -value(1) == -1

    // issue #9643
    foo := Foo{1}
    assert -foo.value() == -1
    assert -(foo.value()) == -1

    arr := [1, 2, 3]
    assert -arr[0] == -1
    assert -arr[1] == -2
}

fn test_positive() {
    two := 2
    assert +two == 2
    assert +(two - 1) == 1
}

fn test_prefix_expr_in_assert_comparison() ! {
    i := 2
    assert strconv.atoi('1')! == 1
    assert strconv.atoi('-2')! == -2
    assert strconv.atoi('+2')! == i - 1 + 1
    assert strconv.atoi('+2')! == -(-2)
    assert strconv.atoi('+2')! == +2
}