use grains::*;

#[test]
fn grains_on_square_1() {
    assert_eq!(square(1), 1);
}

#[test]
fn grains_on_square_2() {
    assert_eq!(square(2), 2);
}

#[test]
fn grains_on_square_3() {
    assert_eq!(square(3), 4);
}

#[test]
fn grains_on_square_4() {
    assert_eq!(square(4), 8);
}

#[test]
fn grains_on_square_16() {
    assert_eq!(square(16), 32_768);
}

#[test]
fn grains_on_square_32() {
    assert_eq!(square(32), 2_147_483_648);
}

#[test]
fn grains_on_square_64() {
    assert_eq!(square(64), 9_223_372_036_854_775_808);
}

#[test]
#[should_panic]
fn square_0_is_invalid() {
    square(0);
}

#[test]
#[should_panic]
fn square_greater_than_64_is_invalid() {
    square(65);
}
#[test]
fn returns_the_total_number_of_grains_on_the_board() {
    assert_eq!(grains::total(), 18_446_744_073_709_551_615);
}