Panic if a route is registered twice

router.go

@@ -43,6 +43,9 @@ func (r *Router) Run(ctx Context) error {
 // Route a [Runner] with the given pattern.
 // Routes are matched in the order they were added.
 func (r *Router) Route(pattern string, runner Runner) {
+	if _, ok := r.runners[pattern]; ok {
+		panic("cannot add route which already exists")
+	}
 	r.patterns = append(r.patterns, pattern)
 	r.runners[pattern] = runner
 }
@@ -76,7 +79,7 @@ type Middleware = func(next Runner) Runner
 // If called in a [Scope], it will apply to all routes in that scope.
 func (r *Router) Use(middlewares ...Middleware) {
 	if len(r.runners) > 0 {
-		panic("cannot use middlewares after adding routes")
+		panic("cannot add middlewares after adding routes")
 	}
 	r.middlewares = append(r.middlewares, middlewares...)
 }

router_test.go

@@ -58,6 +58,24 @@ func TestRouter_RouteFunc(t *testing.T) {
 		is.NotError(t, err)
 		is.True(t, called)
 	})
+
+	t.Run("panics if the route already exists", func(t *testing.T) {
+		r := clir.NewRouter()
+
+		r.RouteFunc("", func(ctx clir.Context) error {
+			return nil
+		})
+
+		defer func() {
+			if rec := recover(); rec == nil {
+				t.FailNow()
+			}
+		}()
+
+		r.RouteFunc("", func(ctx clir.Context) error {
+			return nil
+		})
+	})
 }
 
 func TestRouter_Use(t *testing.T) {
@@ -272,6 +290,22 @@ func TestRouter_Branch(t *testing.T) {
 		is.NotError(t, err)
 		is.Equal(t, "m1\nm2\ndance list\n", b.String())
 	})
+
+	t.Run("panics if the route already exists", func(t *testing.T) {
+		r := clir.NewRouter()
+
+		r.RouteFunc("", func(ctx clir.Context) error {
+			return nil
+		})
+
+		defer func() {
+			if rec := recover(); rec == nil {
+				t.FailNow()
+			}
+		}()
+
+		r.Branch("", func(r *clir.Router) {})
+	})
 }
 
 func newMiddleware(t *testing.T, name string) clir.Middleware {