From e8bc1d99d9df55cecdefc8399346cf11ec2433b9 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Thu, 16 Apr 2026 22:17:34 +0200
Subject: [PATCH] frontend-app-api: deduplicate joinPaths utility in routing

Extract the identical joinPaths function from both
extractRouteInfoFromAppNode.ts and RouteResolver.ts into a shared
joinPaths.ts module, then import it from both consumers.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor
---
 .../src/routing/RouteResolver.ts              | 10 +-------
 .../routing/extractRouteInfoFromAppNode.ts    | 10 +-------
 .../frontend-app-api/src/routing/joinPaths.ts | 24 +++++++++++++++++++
 3 files changed, 26 insertions(+), 18 deletions(-)
 create mode 100644 packages/frontend-app-api/src/routing/joinPaths.ts

diff --git a/packages/frontend-app-api/src/routing/RouteResolver.ts b/packages/frontend-app-api/src/routing/RouteResolver.ts
index 7fd7ef934c..a19105b387 100644
--- a/packages/frontend-app-api/src/routing/RouteResolver.ts
+++ b/packages/frontend-app-api/src/routing/RouteResolver.ts
@@ -31,15 +31,7 @@ import {
   OpaqueSubRouteRef,
 } from '@internal/frontend';
 import { RouteAliasResolver } from './RouteAliasResolver';
-
-// Joins a list of paths together, avoiding trailing and duplicate slashes
-export function joinPaths(...paths: string[]): string {
-  const normalized = paths.join('/').replace(/\/\/+/g, '/');
-  if (normalized !== '/' && normalized.endsWith('/')) {
-    return normalized.slice(0, -1);
-  }
-  return normalized;
-}
+import { joinPaths } from './joinPaths';
 
 /**
  * Resolves the absolute route ref that our target route ref is pointing pointing to, as well
diff --git a/packages/frontend-app-api/src/routing/extractRouteInfoFromAppNode.ts b/packages/frontend-app-api/src/routing/extractRouteInfoFromAppNode.ts
index 4d88fb5fb1..062a54f709 100644
--- a/packages/frontend-app-api/src/routing/extractRouteInfoFromAppNode.ts
+++ b/packages/frontend-app-api/src/routing/extractRouteInfoFromAppNode.ts
@@ -21,6 +21,7 @@ import {
   createExactRouteAliasResolver,
   RouteAliasResolver,
 } from './RouteAliasResolver';
+import { joinPaths } from './joinPaths';
 
 /** @internal */
 export type RouteInfo = {
@@ -41,15 +42,6 @@ export const MATCH_ALL_ROUTE: BackstageRouteObject = {
   routeRefs: new Set(),
 };
 
-// Joins a list of paths together, avoiding trailing and duplicate slashes
-export function joinPaths(...paths: string[]): string {
-  const normalized = paths.join('/').replace(/\/\/+/g, '/');
-  if (normalized !== '/' && normalized.endsWith('/')) {
-    return normalized.slice(0, -1);
-  }
-  return normalized;
-}
-
 export function extractRouteInfoFromAppNode(
   node: AppNode,
   routeAliasResolver: RouteAliasResolver,
diff --git a/packages/frontend-app-api/src/routing/joinPaths.ts b/packages/frontend-app-api/src/routing/joinPaths.ts
new file mode 100644
index 0000000000..89b84bb51c
--- /dev/null
+++ b/packages/frontend-app-api/src/routing/joinPaths.ts
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Joins a list of paths together, avoiding trailing and duplicate slashes
+export function joinPaths(...paths: string[]): string {
+  const normalized = paths.join('/').replace(/\/\/+/g, '/');
+  if (normalized !== '/' && normalized.endsWith('/')) {
+    return normalized.slice(0, -1);
+  }
+  return normalized;
+}