renderToString issue with istanbul and function as child components

[PepijnSenders]

I found this issue whilst comparing snapshots made with jest with and without coverage. When --coverage adds the istanbul babel plugin it adds random elements to the output.

I made a repo where you can see this in action: https://github.com/PepijnSenders/istanbul-preact-render-spy-bug

[sventschui]

What is the intention of passing a function as a child?

What happens here is that the function is serialized to a string and appended to the HTML. Istanbul modifies your code and therefore the string representation of the function looks different.

Either I'm not understanding your usecase or there is an issue with your code. Might you elaborate on your usecase?

Btw. when doing this in react it will not render the function at all. I.e. output would be empty.

[marvinhagemeister]

@sventschui A common use case is the Consumer component from createContenxt:

<Consumer>
  {contextValue => ... }
</Consumer>

[sventschui]

Sure but he is passing a function to an HTML element, not to a component. Thus it ends up as text