Ask HN: Best ways to work on web app views that require complex state to render?

Often when building web applications (be it JS SPA or more traditional templates+server side rendered), there are views that require quite complex state in the backend in order to be rendered.

Concrete example:

User receives an invitation email to access an admin panel of a certain Project. The invitation page requires the following things that it can be rendered:

  - a valid Project with all of its dependencies
  - User+Profile with Invite permissions
  - another User+Profile
  - Session for the other User+Profile
  - an Invitation object
  - etc.

What are some good strategies to allow easy iteration of these kind of views/routes in common web frameworks and libraries?