Testing in Noir

You can test your Noir programs using Noir circuits.

Nargo will automatically compile and run any functions which have the decorator #[test] on them if you run nargo test.

For example if you have a program like:

fn add(x: u64, y: u64) -> u64 {
    x + y
}
#[test]
fn test_add() {
    assert(add(2,2) == 4);
    assert(add(0,1) == 1);
    assert(add(1,0) == 1);
}

Running nargo test will test that the test_add function can be executed while satisfying all the constraints which allows you to test that add returns the expected values. Test functions can't have any arguments currently.

Test fail

You can write tests that are expected to fail by using the decorator #[test(should_fail)]. For example:

fn add(x: u64, y: u64) -> u64 {
    x + y
}
#[test(should_fail)]
fn test_add() {
    assert(add(2,2) == 5);
}

You can be more specific and make it fail with a specific reason by using should_fail_with = "<the reason for failure>":

fn main(african_swallow_avg_speed : Field) {
    assert(african_swallow_avg_speed == 65, "What is the airspeed velocity of an unladen swallow");
}

#[test]
fn test_king_arthur() {
    main(65);
}

#[test(should_fail_with = "What is the airspeed velocity of an unladen swallow")]
fn test_bridgekeeper() {
    main(32);
}

The string given to should_fail_with doesn't need to exactly match the failure reason, it just needs to be a substring of it:

fn main(african_swallow_avg_speed : Field) {
    assert(african_swallow_avg_speed == 65, "What is the airspeed velocity of an unladen swallow");
}

#[test]
fn test_king_arthur() {
    main(65);
}

#[test(should_fail_with = "airspeed velocity")]
fn test_bridgekeeper() {
    main(32);
}