assertEquals doesn't correctly compare Blobs

[EvanHahn]

Describe the bug

assertEquals doesn't consider value-equal Blobs to be equal.

Steps to Reproduce

Run the following code:

import { assertEquals } from "jsr:@std/assert";
assertEquals(new Blob(["foo"]), new Blob(["foo"]));

Expected behavior

This should not throw an error. Instead, it throws AssertionError: Values are not equal.

Environment

• OS: macOS 15
• deno version: 2.1.0
• std version: 1.0.8

[IgorM867]

To compare Blob objects, assertEquals needs to handle asynchronous operations. One approach could be transforming Blob objects into Uint8Array:

import { assertEquals } from "@std/assert";

const bytes1 = await new Blob(["foo"]).bytes();
const bytes2 = await new Blob(["foo"]).bytes();

assertEquals(bytes1, bytes2);

In Node.js, this also doesn’t work:

import assert from "node:assert/strict";

assert.deepStrictEqual(new Blob(["foo"]), new Blob(["foo"]));

@kt3k, what do you think about adding support for Blob in assertEquals and convert it to asynchronous function?

[kt3k]

@IgorM867 Thanks for looking into this. And I don't think we can fix this as assertEquals is a stable API and we can't make breaking change to it. (Changing assertEquals to async function has too large impact to the ecosystem)

I think the best thing we can do is adding note about it, maybe along with the above example.