Adds BigInt support to stringify util function.

[jjsfernandez]

Description of the Change

Fixes #4090, adds a new case to the _stringify function in utils so it can handle the BigInt case.

Alternate Designs

There were two choices considered in the issue BigInt<123> or 123n i went with the latter because it's the standard way JS presents BigInts

Why should this be in core?

Nice way of representing BigInts in errors.

Benefits

Support for Stringify-ing BigInts

Possible Drawbacks

I had to add /* global BigInt */ at the top of the spec file, i don't know if that is the best place for it.

Applicable issues

Fixes #4090

[jsf-clabot]

All committers have signed the CLA.

[coveralls]

Coverage increased (+0.003%) to 94.129% when pulling 2127bcd on JosejeSinohui:issue/4090 into 9878f32 on mochajs:master.

[jjsfernandez]

I already signed the Contributor License Agreement, i don't know why does it show like pending, is there a way to reset it to sign it again?

[boneskull]

it could be a mismatch between username / email address.

some ideas:

• is the email the same in the commits?
• is the email address and username in the CLA tool the same as your github account?
• does email address on github account match the email address you used in the tool?

[boneskull]

the test should be failing in IE11 and maybe safari... hmm.

[jjsfernandez]

the test should be failing in IE11 and maybe safari... hmm.

@boneskull
i checked compatibility here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof

is there something i am missing?

[jjsfernandez]

@boneskull any follow up on this?

[boneskull]

just that those don’t support BigInt but I’m confused about why they weren’t failing CI. could you look in to it? I don’t have time atm. hoping to have more time for project after new year

[jjsfernandez]

From what i see, the CI runs tests only on different NodeJs versions, Node 8 doesn't support BigInts either but I only added a new case to the stringify function, in that case it uses the toString function to create the representation of the BigInt, so the code it's never instantiating a BigInteger, just knows how to handle one if it ever receives it.
The build was failing before because in the test that I added was creating a BigInt to test that it was correctly parsed into a string with the stringify function. Because of this the test didn't pass in node8 because BigInteger wasn't supported there. To fix it I just added a check for support before trying it.

[mvlabat]

Mocha just hangs for me when it tries to assert equality of two different bigints (it's fine when they are equal though). Might it be related to the issue that this PR fixes?

@boneskull any chance this PR gets merged anytime soon? Sorry to nudge.

[mattbishop]

👍 BigInt support is widespread in 2021: https://caniuse.com/?search=bigint

[juergba]

I rebased to master branch.
I don't know why the ESLint test is failing, I will have a look later.
The cancelled browser test (pull_request) is off-topic, due to our GH actions setup.

[juergba]

GH actions has problems with downloading an artifact and therefore the ESLint tests fail. It doesn't seem to be related to this PR.
I restarted our CI tests on another, successfully passing PR and the ESLint tests fail now.
It's not the first time GH actions is behaving weirdly.

[juergba]

@JosejeSinohui thank you. I apologize for the long delay.