Find helper results null when query has empty result

[pixelhandler]

Originally the find helper returns an empty NodeList when the query has an empty result. Alternatively if the query has only a single result, instead of returning the NodeList with one HTMLElement the find helper returns the only result the HTMLElement.

The check for an empty result is find('.not-present').length === 0. Since the helper is acting intuitive like either document.querySelector or document.querySelectorAll the return value should be similar. No result from querySelector is null and an no results from querySelectorAll is an empty NodeList.

Checking for a null result when a query is made for one matching element makes sense. The find helper doesn't know that the result should be one or more based on the query. So returning an empty NodeList seems less than ideal.

Returning null, HTMLElement or NodeList[HTMLElement] is the gist of this PR.

Alternatively we could use two helpers, find(string) null | HTMLElement and findAll(string) NodeList[] (the node list may be empty when the query has no matching result.

Fixes #13

[cibernox]

I'm not agains the idea of find/findAll actually. It seems a cleaner solution than having a helper that returns a NodeList sometimes and single element if it happens to be only one item in the list.

Also thinking in Typescript, having two monomorphic function would lead to better types and IDE assistance.

[pixelhandler]

Yeah I like find/findAll too, should play nicer with TypeScript

[sarjanen]

I like this, my only concern with findAll is if integration and acceptance test selectors should be the same? Know that this is a addon but i guess that the main goal is that this should be the implemantation of Grand Testing Unification?
The RFC can change and the find/findAll make sense like @cibernox says. Merge 😉

Edit, actually when findAll would be nice in acceptance test to.

[pixelhandler]

@cibernox @Padchi @rwjblue perhaps merging this is only an iteration maybe we need two helpers later.

[pixelhandler]

Since we're iterating on what makes for good native test helpers I propose we merge in this PR and release v0.2.1 - then try out find(selector: string): null | HTMLElement and findAll(selector: string): NodeList which work using document.querySelector and document.querySelectorAll. on a 0.3.0 tag.

[pixelhandler]

The use case for having a null response is that it's weird to expect result instanceof HTMLElement || result.length > 1 as an assertion for presence of a result (not empty).