I need to add, about Router.Group() providing the sub-router with a “fresh” middleware stack… That's not the case at all!

package main

import (
	"fmt"
	"net/http"

	"github.com/go-chi/chi/v5"
)

func main() {
	router := chi.NewRouter()
	router.Use(dummyMiddleware)
	router.Group(func(subRouter chi.Router) {
		fmt.Println("Middlewares of sub-router inside Router.Group():", subRouter.Middlewares())
		subRouter.Get("/foo", func(w http.ResponseWriter, r *http.Request) {
			_, _ = w.Write([]byte("foo"))
		})
	})
	panic(http.ListenAndServe(":8080", router).Error())
}

func dummyMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Println("dummyMiddleware!")
		next.ServeHTTP(w, r)
	})
}

Run this, query /foo, and you'll see dummyMiddleware! printed, despite the route definition inside Router.Group() supposedly having been served a “fresh” middlware stack and the fmt.Println() call in there printing Middlewares of sub-router inside Router.Group(): [] (i.e., apparently no middlewares in effect from this point of view)!

Is this intentional? If so, does this mean that the sub-router gets the stack of middlewares of the parent router but its additions do not propagate to the latter? If this is the case, this means that you cannot use Router.Group() to define routes that don't get the middleware stack of the parent router and that the slice of middlewares returned by Router.Middlewares() on the sub-router does not include those of the parent router. Then the Router.Group() should really be documented more clearly (WRT the definition of “fresh middleware stack”).

this is all intentionally yes. nothing we can do about it. sorry for the confusion, but this is how it is. the .Group() is a helper for inline-middleware handlers. Feel free to read the code to see find the answers why the design is constrained this way.

router.Group() doesn't provide a sub-router with a “fresh” middleware stack

it provides with a copy of parent middleware stack, on top of which you can apply middleware specific to the group only

@pkieltyka perhaps the godoc might be a bit misleading?

	// Group adds a new inline-Router along the current routing
	// path, with a fresh middleware stack for the inline-Router.
	Group(fn func(r Router)) Router

Yep, as I said, that at least could do with some clarification.

@curio77 would you be able to improve the godoc for the Group() method and submit a PR, please?

Yep, will do…

I'd like to add that it feels kinda weird to document such intrinsics/caveats on an interface method. Don't know whether it's actually just intrinsics of the implementation in chi.Mux, but if that's the foremost manifestation of the interface users will deal with…