beizhedenglong / reason-hooks-testing-library Goto Github PK

The renderHook function accepts an optional object with options as the second argument, and the signature looks like this

function renderHook(
  callback: function(props?: any): any,
  options?: RenderHookOptions
): RenderHookResult

where RenderHookOptions has a property wrapper which can be used to add context provider from React.createContext when testing hooks that use useContext.

I am developing a library that uses useContext and will need to write tests leveraging the wrapper option, it would be nice to have this functionality so I will open a PR 🙂

When I use act(), I get the following warning:

Warning: The callback passed to act(...) function must return undefined, or a Promise. You returned
 0

Which is totally understandable, because the signature for the callback is unit => unit, and () is compiled to 0.

One solution would be to change the signature to unit => Js.undefined. Another one is to introduce a non-zero-cost wrapper that effectively calls act(() => { callback(); Js.undefined; }).