Simple Test Framework JavaScript (in browser)

all.test.js

// add tests here, comment out to disable
import "./example.test.js";

console.log("This should only show up when running tests");

example.test.js

import { test, assert } from "test.js";

test("1+1", () => {
  assert(1 + 1 === 2);
});

test.js

/** @type {[string, () => Promise<void> | void][]} */
const tests = [];

/**
 *
 * @param {string} description
 * @param {() => Promise<void> | void} testFunc
 */
export async function test(description, testFunc) {
  tests.push([description, testFunc]);
}

export async function runAllTests() {
  const main = document.querySelector("main");
  if (!(main instanceof HTMLElement)) throw new Error();
  main.innerHTML = "";

  for (const [description, testFunc] of tests) {
    const newSpan = document.createElement("p");

    try {
      await testFunc();
      newSpan.textContent = `✅ ${description}`;
    } catch (err) {
      const errorMessage =
        err instanceof Error && err.message ? ` - ${err.message}` : "";
      newSpan.textContent = `❌ ${description}${errorMessage}`;
    }
    main.appendChild(newSpan);
  }
}

/**
 * @param {any} val
 */
export function assert(val, message = "") {
  if (!val) throw new Error(message);
}