Test an application

Write application tests with maligator:test. Ordinary maligator test interprets a compiled development image and does not invoke a native C compiler or linker.

Write a test

Create these files in a project with maligator.build.ts:

export function sum(values: ReadonlyArray<number>): number {
	return values.reduce((total, value) => total + value, 0);
}

import { describe, expect, test } from "maligator:test";
import { sum } from "./sum.ts";

describe("sum", () => {
	test("adds values", () => {
		expect(sum([1, 2, 3])).toBe(6);
	});
	test("accepts an empty input", () => {
		expect(sum([])).toBe(0);
	});
});

maligator test sum.test.ts

The runner reports both tests as passed. It discovers *.test.{js,mjs,ts,mts} and *.spec.{js,mjs,ts,mts} when given directories or no explicit files. Successful results are never cached: every selected test executes on each run.

Filter and repeat tests

maligator test --run "sum adds values"
maligator test --shuffle 42 --repeat 3
maligator test --timeout 10000 --bail

--run filters hierarchical suite/test names. Selection is stable and serial by default. The callback timeout defaults to 5000 milliseconds. --shuffle prints its seed; keep that seed to reproduce the order. --repeat reruns the registered suite without recompiling. --bail stops after the first failure; ordinary runs complete the selection.

Use test.skip, test.todo, and test.only for temporary selection. Any .only skips non-focused tests and prints a warning. Remove focus before sharing the suite.

Await asynchronous assertions

import { expect, test } from "maligator:test";

test("awaits a value", async () => {
	await expect(Promise.resolve({ answer: 42 })).resolves.toEqual({ answer: 42 });
	await expect(Promise.reject(new Error("unavailable"))).rejects.toThrow("unavailable");
});

Return or await promises from test and hook callbacks. Await .resolves and .rejects matchers so the assertion finishes before the test does. Suite callbacks passed to describe must be synchronous. See matchers and hooks for the exact contracts.

Watch or isolate a suite

maligator test --watch --status
maligator test --isolate --compile-concurrency 2 --concurrency 2

Watch mode retains compiled images and starts a fresh application on each rerun. On POSIX, sending SIGHUP to the printed PID reruns unchanged inputs. Add --watch-failed to select previously failing files for those unchanged reruns.

Selected files normally share one application isolate, including module singletons and globals. --isolate gives each file separate application state; --compile-concurrency and --concurrency bound compilation and execution separately. Isolation requires a compatible native runtime policy. The supervisor joins the application and its descendants after every run, including resources tests left open.

--profile compiles a production AOT test image for profiling. It cannot be combined with --watch or --isolate and requires the native toolchain. See CLI test flags.

For tests of the compiler repository itself, follow Develop Maligator.