Compare non-plain objects in .expectRender()

[kitsonk]

Enhancement

Because there are potentially properties in widgets that are not plain objects (e.g. registries) when comparing renders we need ways of representing the expected render without being able to get a reference to the non-plain object.

We can compare these "exotic" objects based that their .prototype is strictly equal and not introspect the object further or descend into its properties. This would allow for specification of instances of these objects being present in the render.

[kitsonk]

An alternative approach would be to use something like:

widget.expectedRender(w(Widget, {
    registry: widget.compare((value) => value.prop === 'foo')
}));