Use fancy diffs for node's assert.deepEqual

[glenjamin]

Is there a reason why only opted-in 3rd-party libraries get the fancy coloured/unified diff feature?

I wasn't sure, so here's a PR that detects node core's deepEqual and lets it get the nice diff behaviour. 🎉

[boneskull]

@glenjamin So it appears when the assert module throws an Error, it stuffs an operator property into the Error? Is this documented anywhere?

[glenjamin]

It's not documented extremely well, I might send a PR up to Node core to make it explicit.

The assert module is marked as "Stable", so should not change anymore.

This function hints at this behvaiour:
http://nodejs.org/docs/latest/api/assert.html#assert_assert_fail_actual_expected_message_operator

And here's the AssertionError constructor:
https://github.com/joyent/node/blob/master/lib/assert.js#L40

[jbnicolai]

@boneskull @glenjamin is there anything holding of a merge?

[jbnicolai]

This PR is currently no longer mergable, and with the inclusion of unexpectedjs I think it's no longer relevant either.

Feel free to update if you think it still adds value though, and thanks for the effort!

[glenjamin]

Could you point me towards the PR for the unexpected change you're referring to? I tried to search but couldn't seem to find anything.

The specific aim here was to improve formatting when using Node core's assert.deepEqual, I'm happy to rebase the PR.

[jbnicolai]

This one (which was indeed tricky to find): #1349

But now that I'm looking at it, it seems this was only for the HTML reporter. If you'd like to rebase your changes I'd be happy to have an other look at merging them :)

[glenjamin]

I looked into this a bit more, the change is no longer needed due to #1626 which changes the default behaviour to always show diffs.

[jbnicolai]

@glenjamin 👍 thanks