Blob is not instance of Blob

[nakleiderer]

It appears that Blob is not an instance of Blob. Here's a minimal repro on StackBlitz using Vitest:
https://stackblitz.com/edit/happy-dom-bug-blob-prototype?file=README.md

This caused the following error when using the @web-std/file package after upgrading from vitest@0.11.0 to vitest@0.12.0

TypeError: Class extends value does not have valid prototype property undefined
Object. node_modules/@web-std/file/dist/src/file.cjs:59:15
Object. node_modules/@web-std/file/dist/src/lib.node.cjs:6:12

I'm not sure if there's also a bug in Vitest or not, but the fact that Blob.prototype is undefined appears to be the root cause. The error only occurs when using the happy-dom environment, so I believe this is the appropriate place to open an issue.

[capricorn86]

Thanks for reporting @nakleiderer! 🙂

Not sure exactly what is happening yet, but it seem to be related to the way Vitest is setup. They probably have to fix this.

I ran some tests in your test environment:

// Outputs "false"
console.log(window.globalThis === globalThis)

// Outputs "false"
console.log(window.Blob === globalThis.Blob)

// Outputs "false"
console.log(window.globalThis.Blob === globalThis.Blob)

// Outputs "false"
console.log(Blob === globalThis.Blob)

I will have to look into how Vitest is setup to understand what goes wrong.

The first test is not completely correct. It should be new Blob() instanceof Blob or new globalThis.Blob() instanceof globalThis.Blob.

[capricorn86]

@nakleiderer I have reported the bug to Vitest now as I believe it is related to how Vitest implements Happy DOM.

[capricorn86]

@nakleiderer this should be solved in the latest version of Vitest 🙂

[rijkvanzanten]

Heya! Sorry to revive this old issue, but I believe I'm running into the same, if not a similar problem. The original test case you provided now all works as it should:

// Outputs "true"
console.log(window.globalThis === globalThis)

// Outputs "true"
console.log(window.Blob === globalThis.Blob)

// Outputs "true"
console.log(window.globalThis.Blob === globalThis.Blob)

// Outputs "true"
console.log(Blob === globalThis.Blob)

but the following throws an error similar to the OP:

window.URL.createObjectURL(new Blob());
// => The "obj" argument must be an instance of Blob. Received an instance of Blob

Is this related to implementing Document.URL as per #526? I'm a little lost in the nuances between environments and test runners, so apologies if this is a configuration issue/known problem/missing feature/etc..

Thanks!

[nickrum]

window.URL.createObjectURL(new Blob());
// => The "obj" argument must be an instance of Blob. Received an instance of Blob

It seems like Vitest is using Node's version of URL, but happy-dom's version of Blob. The error is caused by Node's URL.createObjectURL() receiving an instance of happy-dom's Blob. But even if Vitest would use happy-dom's URL, that wouldn't help much because AFAIK it doesn't yet implement URL.createObjectURL().

[davidortner-ipex]

I am continuing the work in #520 right now where we will replace the Happy DOM URL with Nodes version of it. Hopefully that will solve this issue then.

[akkie]

With happy-dom 8.9.0 I face the same issue as @nickrum.

window.URL.createObjectURL(new Blob());
// => The "obj" argument must be an instance of Blob. Received an instance of Blob

Do I miss something?