From 4df75cd2b2bae67f34a26ba8f17528805c463562 Mon Sep 17 00:00:00 2001
From: Taichi Sasaki <tchssk@users.noreply.github.com>
Date: Thu, 28 Sep 2023 09:34:14 +0900
Subject: [PATCH] Use RedirectSlashes middleware by default Goa mux  (#3366)

* Test redirection for URLs with trailing slashes

* Use RedirectSlashes middleware by default Goa mux

* Mount at the top level of the router
---
 http/mux.go      |  4 ++++
 http/mux_test.go | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/http/mux.go b/http/mux.go
index f918c877fd..11013ecb3a 100644
--- a/http/mux.go
+++ b/http/mux.go
@@ -8,6 +8,7 @@ import (
 	"regexp"
 
 	chi "github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
 )
 
 type (
@@ -79,6 +80,9 @@ type (
 // NewMuxer returns a Muxer implementation based on a Chi router.
 func NewMuxer() ResolverMuxer {
 	r := chi.NewRouter()
+	// RedirectSlashes must be mounted at the top level of the router.
+	// See. https://github.com/go-chi/chi/blob/1129e362d6cce6e3805e3bc8dfbaeb34b5129789/middleware/strip_test.go#L105-L107
+	r.Use(middleware.RedirectSlashes)
 	r.NotFound(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
 		ctx := context.WithValue(req.Context(), AcceptTypeKey, req.Header.Get("Accept"))
 		enc := ResponseEncoder(ctx, w)
diff --git a/http/mux_test.go b/http/mux_test.go
index f3eacc1798..94f59781db 100644
--- a/http/mux_test.go
+++ b/http/mux_test.go
@@ -227,6 +227,16 @@ func TestResolvePattern(t *testing.T) {
 			w := httptest.NewRecorder()
 			mux.ServeHTTP(w, req)
 			assert.True(t, called)
+			// Make sure the URL with a trailing slash is redirected.
+			called = false // Reset.
+			req, _ = http.NewRequest("GET", c.URL+"/", nil)
+			w = httptest.NewRecorder()
+			mux.ServeHTTP(w, req)
+			assert.Equal(t, http.StatusMovedPermanently, w.Code)
+			req, _ = http.NewRequest("GET", w.Header().Get("Location"), nil)
+			w = httptest.NewRecorder()
+			mux.ServeHTTP(w, req)
+			assert.True(t, called)
 		})
 	}
 }