Add tests for mount point conflicts and deep nested mounts

group_test.go

@@ -2244,6 +2244,131 @@ func TestMiddlewareOrder(t *testing.T) {
 	}
 }
 
+func TestMountPointMethodConflicts(t *testing.T) {
+	group := routegroup.New(http.NewServeMux())
+
+	// register handler for /api directly
+	group.HandleFunc("GET /api", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("api root"))
+	})
+
+	// mount a group at /api
+	api := group.Mount("/api")
+	api.HandleFunc("/users", func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("users"))
+	})
+
+	srv := httptest.NewServer(group)
+	defer srv.Close()
+
+	t.Run("get /api root", func(t *testing.T) {
+		resp, err := http.Get(srv.URL + "/api")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer resp.Body.Close()
+
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("expected status 200, got %d", resp.StatusCode)
+		}
+		if string(body) != "api root" {
+			t.Errorf("expected 'api root', got %q", string(body))
+		}
+	})
+
+	t.Run("get /api/users", func(t *testing.T) {
+		resp, err := http.Get(srv.URL + "/api/users")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer resp.Body.Close()
+
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			t.Errorf("expected status 200, got %d", resp.StatusCode)
+		}
+		if string(body) != "users" {
+			t.Errorf("expected 'users', got %q", string(body))
+		}
+	})
+}
+
+func TestDeepNestedMounts(t *testing.T) {
+	var callOrder []string
+	mkMiddleware := func(name string) func(http.Handler) http.Handler {
+		return func(next http.Handler) http.Handler {
+			return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				callOrder = append(callOrder, "before "+name)
+				next.ServeHTTP(w, r)
+				callOrder = append(callOrder, "after "+name)
+			})
+		}
+	}
+
+	group := routegroup.New(http.NewServeMux())
+	group.Use(mkMiddleware("root"))
+
+	v1 := group.Mount("/v1")
+	v1.Use(mkMiddleware("v1"))
+
+	api := v1.Mount("/api")
+	api.Use(mkMiddleware("api"))
+
+	users := api.Mount("/users")
+	users.Use(mkMiddleware("users"))
+
+	users.HandleFunc("/list", func(w http.ResponseWriter, _ *http.Request) {
+		callOrder = append(callOrder, "handler")
+		_, _ = w.Write([]byte("users list"))
+	})
+
+	srv := httptest.NewServer(group)
+	defer srv.Close()
+
+	resp, err := http.Get(srv.URL + "/v1/api/users/list")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("expected status 200, got %d", resp.StatusCode)
+	}
+	if string(body) != "users list" {
+		t.Errorf("expected 'users list', got %q", string(body))
+	}
+
+	expected := []string{
+		"before root",
+		"before v1",
+		"before api",
+		"before users",
+		"handler",
+		"after users",
+		"after api",
+		"after v1",
+		"after root",
+	}
+
+	if !reflect.DeepEqual(callOrder, expected) {
+		t.Errorf("middleware execution order mismatch\nwant: %v\ngot:  %v", expected, callOrder)
+	}
+}
+
 func ExampleNew() {
 	group := routegroup.New(http.NewServeMux())