Add Test Coverage

[busypeoples]

No description provided.

[busypeoples]

We will need a strategy here. function.toString() seems to cause troubles in an instanbul context. This will break the propsToVariation function tests.

gotwarlost/istanbul#310

// istanbul context
"onClick": function onClick(){__cov_YrynSvfAB9MZhTh3r7xFHA.f['16']++;__cov_YrynSvfAB9MZhTh3r7xFHA.s['55']++;return undefined;}

// normal context
"onClick": function onClick() {
    return undefined;
}

[nikgraf]

@busypeoples
@neuling had the idea to potential call these function with an apply. This would fix the test and potential avoid context issues on the front-end?!?

[busypeoples]

Sounds good. Let's give it try. Avoiding function.toString(), will definitely fix this specific issue. All other tests work out of the box with istanbul.

[busypeoples]

I think we can close this issue. All tests run through. @nikgraf