Sinon.assert does not work with new dates form Sinon timers

[krystianolech]

Hello, I noticed that on Sinon 19 some of my test stoped working.
Case where it happen is related to situations where fakeTimers are used with something that is passed to function and later asserted by Sinon.match.

Here is minimal code to reproduce it:

import * as Sinon from "sinon";

const now = new Date("2024-01-01");
const clock = Sinon.useFakeTimers({
  now,
  toFake: ["Date"],
});

const stub = Sinon.stub();

stub(new Date());

Sinon.assert.calledWith(stub, now);

This code works fine on v18 but it fails on v19.

[fatso83]

This is interesting. The code fails when running with the latest Sinon from NPM, but it does not fail with the latest source code in the repo 🤔

✦ ❯ cat my-test.mjs
import * as Sinon from "sinon";
import { test } from "mocha";

test("test date", function () {
  const now = new Date("2024-01-01");
  const clock = Sinon.useFakeTimers({
    now,
    toFake: ["Date"],
  });

  const stub = Sinon.stub();

  stub(new Date());

  Sinon.assert.calledWith(stub, now);
});

✦ ❯ npx mocha my-test.mjs


  1) test date

  0 passing (7ms)
  1 failing

  1) test date:
     AssertError: expected stub to be called with arguments
Mon Jan 01 2024 01:00:00 GMT+0100 (GMT+01:00)
      at Object.fail (file:///private/tmp/node_modules/sinon/pkg/sinon-esm.js:131:27)
      at failAssertion (file:///private/tmp/node_modules/sinon/pkg/sinon-esm.js:274:20)
      at assert.<computed> [as calledWith] (file:///private/tmp/node_modules/sinon/pkg/sinon-esm.js:303:17)
      at Context.<anonymous> (file:///private/tmp/my-test.mjs:15:16)
      at process.processImmediate (node:internal/timers:478:21)

Now using a reference to the build in locally

# First did this
cd ~/dev/sinon
npm run build

Changed the top line to read

import * as Sinon from "./pkg/sinon-esm.js";

then ran it:

npx mocha my-test.mjs


  ✔ test date

  1 passing (5ms)

Not expected.