fix(createURL): support multi-index

[francoischalifour]

Description

This updates the signature of the createURL function given to widgets' lifecycle (init and render). It also updates the undocumented top-level createURL to match the same signature.

New signature

The signature at the widget level (given to the init and render hooks) stays the same:

createURL(nextState: SearchParameters): string;

However, the internal signature in the index widget changes and uses the UI state.

createURL(nextState: UIState): string;

This UI state is accumulated with all the widgets mounted on the instance, which results in the complete UI state of the sub indices.

This change is especially needed for generating exhaustive URLs for both currentRefinement and clearRefinements.

Current architecture limitations

The new architecture for v4 proceeds top to bottom. This means that if you call createURL in a top-level widget init hook, it ignores the uiState of all children. This results in an incomplete URL string.

This likely will never happen in user code because we rarely only use init without render. Still, if we've got complains about incomplete URLs, we can suggest adding a render method to fix the issue.

Notes on top-level createURL

The top-level createURL method has never been documented and was initially introduced for our Magento integration. This is not used anymore so we might consider removing this method by the time we go stable.

See #372 and #377.

What's remaining

There are some checks that we need to proceed and to fix in others PRs if the result is not expected.

• Check the createURL usage in currentRefinements
• Check the createURL usage in clearRefinements

[samouss]

If the tests are concluant it looks like we're good.

[Haroenv]

merged, since @francoischalifour can't :)