describe should throw if passed a function that returns a promise

[lucacasonato]

describe is used to group related tests. Actual test code should be put in an it block or a before*/after* hook. For example, you can initialize node in a beforeAll hook:

import { beforeAll, describe, it } from "jsr:@std/testing@^0.220.1/bdd";
import { assertEquals } from "jsr:@std/assert@^0.220.1/assert_equals";

describe("DOMNode", () => {
  let node;

  beforeAll(async () => {
    node = await xmlFromString(…);
  });

  it("in root namespace", () => assertEquals(…));
  it("in leaf namespace", () => assertEquals(…));
});

Deno.test equivalent

import { assertEquals } from "jsr:@std/assert@^0.220.1/assert_equals";

Deno.test("DOMNode", async (t) => {
  let node = await xmlFromString(…);

  await t.step("in root namespace", () => assertEquals(…));
  await t.step("in leaf namespace", () => assertEquals(…));
});

The error message could definitely be improved. Jest throws a helpful error if the callback passed to describe returns a promise or anything other than undefined.

Originally posted by @0f-0b in denoland/deno#22991 (comment)

[kt3k]

Hey @KyleJune, can you take a look at this?

[KyleJune]

Hey @KyleJune, can you take a look at this?

All the call signatures already only accept callbacks that return void. I believe the issue would have been caught if they were using TypeScript but I think it would be fine to add a check to the code so that JavaScript users will get an error if they try having it return anything.