And find_pattern middleware

middleware/find_pattern.go

@@ -0,0 +1,29 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+)
+
+// Find the route pattern for the request path.
+//
+// This middleware does not need to be the last middleware to resolve the
+// route pattern. The pattern is fully resolved before the request has been
+// handled.
+func FindPattern(routes chi.Routes, callback func(pattern string)) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			// Find mutates the context so always make a new one
+			rctx := chi.NewRouteContext()
+			path := r.URL.Path
+			op := r.Method
+			pattern := routes.Find(rctx, op, path)
+			callback(pattern)
+
+			next.ServeHTTP(w, r)
+		}
+		return http.HandlerFunc(fn)
+	}
+
+}

middleware/find_pattern_test.go

@@ -0,0 +1,67 @@
+package middleware
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+)
+
+func TestFindPattern(t *testing.T) {
+	t.Parallel()
+
+	var tests = []struct {
+		pattern string
+		path    string
+	}{
+		{
+			"/",
+			"/",
+		},
+		{
+			"/hi",
+			"/hi",
+		},
+		{
+			"/{id}",
+			"/123",
+		},
+		{
+			"/{id}/hello",
+			"/123/hello",
+		},
+		{
+			"/users/*",
+			"/users/123",
+		},
+		{
+			"/users/*",
+			"/users/123/hello",
+		},
+	}
+
+	for _, tt := range tests {
+		var tt = tt
+		t.Run(tt.pattern, func(t *testing.T) {
+			t.Parallel()
+
+			recorder := httptest.NewRecorder()
+
+			r := chi.NewRouter()
+			r.Use(FindPattern(r, func(pattern string) {
+				if pattern != tt.pattern {
+					t.Errorf("actual pattern \"%s\" does not equal expected pattern \"%s\"", pattern, tt.pattern)
+				}
+			}))
+
+			r.Get(tt.pattern, func(w http.ResponseWriter, r *http.Request) {
+				w.Write([]byte(""))
+			})
+
+			req := httptest.NewRequest("GET", tt.path, nil)
+			r.ServeHTTP(recorder, req)
+			recorder.Result()
+		})
+	}
+}