Developer Test Cases/Unit Tests

[SuperFromND]

This is something that's been brought up a couple times now on the Discord, so I'm gonna throw it on here: Ikemen currently lacks any proper unit tests, and it'd be pretty beneficial to have them around since beta-testers can only find so much in terms of regressions.

For the laymen reading: unit tests are a set of internal tests that make sure a given feature or function works as intended and doesn't break when given unusual inputs. These are usually ran automatically whenever changes are made to the specific feature or function, or triggered manually by a developer.

Here's a basic example of a unit test in JavaScript, to show what they look like:

// example function; adds two numbers together and then returns the result
function add(one, two) {
    return one + two;
}

// test function, runs a bunch of unit tests on add()
function test_add() {
    // does the function work at all?
    console.log("test 1, expected output: 4");
    console.log(add(2, 2));

    // does it work with large numbers?
    console.log("test 2, expected output: 65534");
    console.log(add(32767, 32767));

    // how about negative numbers?
    console.log("test 3, expected output: -40");
    console.log(add(20, -60));

    // what if one of the values is null?
    console.log("test 4, expected output: 2");
    console.log(add(2, null));

    // what if both are null?
    console.log("test 5, expected output: 0");
    console.log(add(null, null));
}

// run unit test
test_add();

We do kinda already do unit tests in the form of asking for test characters/stages when people report engine bugs, but it would be more beneficial to have dedicated unit tests so we don't have to juggle around a bunch of test characters every time we change something, not to mention it'd be more efficient.