assertRejects does not fail when an error is thrown, but a promise was not rejected

Describe the bug

import { assertRejects } from "https://raw.githubusercontent.com/denoland/deno_std/main/testing/asserts.ts";
await assertRejects(function () { throw new Error("test") });

Expected behavior Should throw because no promise was rejected.

Node’s assertRejects behaviour:

> assert.rejects(function() { throw new Error("test"); }).catch(err => console.log(err));
> Error: test
    at REPL16:1:35
    at waitForActual (assert.js:786:21)
    at Function.rejects (assert.js:921:31)
    at REPL16:1:8
    at Script.runInThisContext (vm.js:134:12)
    at REPLServer.defaultEval (repl.js:486:29)
    at bound (domain.js:416:15)
    at REPLServer.runBound [as eval] (domain.js:427:12)
    at REPLServer.onLine (repl.js:819:10)
    at REPLServer.emit (events.js:387:35)

This might just be an issue with the renaming from assertThrowsAsync -> assertRejects and perhaps we should keep assertThrowsAsync then change assertRejects to assert that a promise is rejected?

[Sorikairox]

Okay my bad, I totally missed the point of synchronicity, which was the subject of this issue, and went in an insanely wrong direction. Doesn’t feel good to be dumb 😆

Sorry for (unintentionally) wasting your time.

[dsherret]

View async functions as only rejecting a promise because that’s what they do.

Before changes :

• assert that a function throws => use assertThrows
• assert that an async function rejects/throws => use assertRejects
• assert that a function that returns a promise throws synchronously => use assertThrows, but right now assertRejects incorrectly passes

After changes:

• assert that a function throws => use assertThrows
• assert that an async function rejects/throws => use assertRejects
• assert that a function that returns a promise throws synchronously => use assertThrows and assertRejects should fail because it throws synchronously