frontend-app-api: initial routing system implementation

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/frontend-plugin-api/src/index.ts

@@ -37,3 +37,4 @@ export {
   type ExtensionDataValue,
 } from './types';
 export * from './wiring';
+export * from './routing';

packages/frontend-plugin-api/src/routing/index.ts

@@ -0,0 +1,17 @@
+/*
+ * 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.
+ */
+
+export { useRouteRef } from './useRouteRef';

packages/frontend-plugin-api/src/routing/useRouteRef.ts

@@ -15,11 +15,12 @@
  */
 
 import { RouteRef } from '@backstage/core-plugin-api';
+// eslint-disable-next-line @backstage/no-forbidden-package-imports
 import { RoutingContext } from '@backstage/frontend-app-api/src/routing/RoutingContext';
 import { useContext, useMemo } from 'react';
 import { useLocation } from 'react-router-dom';
 
-export function useRouteRef(routeRef: RouteRef<any>): () => string | undefined {
+export function useRouteRef(routeRef: RouteRef<any>): () => string {
   const { pathname } = useLocation();
   const resolver = useContext(RoutingContext);
 
@@ -28,5 +29,9 @@ export function useRouteRef(routeRef: RouteRef<any>): () => string | undefined {
     [resolver, routeRef, pathname],
   );
 
+  if (!routeFunc) {
+    throw new Error(`Failed to resolve routeRef ${routeRef}`);
+  }
+
   return routeFunc;
 }