[Tests] Extend findWhere null nodes test

[angelikatyborska]

As requested by @ljharb, this is a failing test case for issue #1566.

expect(spy.callCount).to.equal(3); - I am not certain if this assertion should expect 3 calls or 4 calls. That depends if the null node that is currently passed will be skipped or fixed not to be null.

(Now fixes #1566)

[mhuggins]

+1 on merging this and getting a fix.

[ljharb]

Hmm - I'm not sure I think there's a bug here. I think that it makes sense for findWhere to receive every node - specifically in case it wants to find text nodes - and that it makes sense for .getDOMNode() to return null on text nodes.

However, I think that .text() on a textNode should just return the text, so i'll update this PR with the updated tests, and then add a fix.

Thank you - this helped me understand the problem!

[ljharb]

LGTM - @angelikatyborska, do you agree?

[ljharb]

I'm going to merge this.

[xixixao]

This changes the type of text() to be ?string, so we should update Flow types (and presumably TS?).

[ljharb]

@xixixao we don't use or maintain our own types, so please file issues in the appropriate places.