Snapshot serializer doesn't work with DOMStringMap and NamedNodeMap

[stefanbuck]

Do you want to request a feature or report a bug?
I suppose this could be considered a feature request.

What is the current behavior?

Jest throws an error when I try to serialize a DOMStringMap or NamedNodeMap. The output is:

RangeError: Invalid string length

If the current behavior is a bug, please provide the steps to reproduce and
either a repl.it demo through https://repl.it/languages/jest or a minimal
repository on GitHub that we can yarn install and yarn test.

The test is very simple:

const el = document.createElement('div');
el.dataset.foo = 'bar';

expect(el.dataset).toMatchSnapshot();

Same behavior for NamedNodeMap

const el = document.createElement('div');
el.dataset.foo = 'bar';

expect(el.attributes).toMatchSnapshot();

What is the expected behavior?

Jest should be able to serialize DOMStringMap and NamedNodeMap so I can reduce snapshot output to the values which I am interested in.

As a workaround, I spread the values into a new object.

expect({...el.dataset}).toMatchSnapshot();

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.

jest@22.0.4
yarn@1.3.2
node@8.9.1

[rogeliog]

I can reproduced the same error, not sure what it is

[thymikee]

cc @pedrottimark

[zouxuoz]

@rogeliog

I think it's not a bug, because DOMStringMap is very large object and Node can be fall in this case.

We can hardcode custom serialization for this case, but I'm think it's bad way.

It's a JSDOM problem, because browser doesn't have it. May be this jsdom/jsdom#1129 update resolve it.

[SimenB]

We can hardcode custom serialization for this case, but I'm think it's bad way.

We do that for lots of stuff already, including HTMLElements

[zouxuoz]

@SimenB oh, thx, I find it and can fix this bug.

[github-actions]

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