Merge pull request #33152 from backstage/rugvip/use-api-holder-no-throw

frontend-plugin-api: change `useApiHolder` to not throw outside API context

packages/frontend-plugin-api/src/apis/system/useApi.test.tsx

@@ -17,7 +17,30 @@
 import { renderHook } from '@testing-library/react';
 import { createVersionedContextForTesting } from '@backstage/version-bridge';
 import { createApiRef } from './ApiRef';
-import { useApi } from './useApi';
+import { useApi, useApiHolder } from './useApi';
+
+describe('useApiHolder', () => {
+  const context = createVersionedContextForTesting('api-context');
+
+  afterEach(() => {
+    context.reset();
+  });
+
+  it('should return the API holder from context', () => {
+    const holder = { get: jest.fn() };
+    context.set({ 1: holder });
+
+    const renderedHook = renderHook(() => useApiHolder());
+    expect(renderedHook.result.current).toBe(holder);
+  });
+
+  it('should return an empty API holder when there is no context', () => {
+    const renderedHook = renderHook(() => useApiHolder());
+
+    const holder = renderedHook.result.current;
+    expect(holder.get(createApiRef<string>({ id: 'x' }))).toBeUndefined();
+  });
+});
 
 describe('useApi', () => {
   const context = createVersionedContextForTesting('api-context');

packages/frontend-plugin-api/src/apis/system/useApi.tsx

@@ -19,6 +19,8 @@ import { ApiRef, ApiHolder, TypesToApiRefs } from './types';
 import { useVersionedContext } from '@backstage/version-bridge';
 import { NotImplementedError } from '@backstage/errors';
 
+const emptyApiHolder: ApiHolder = Object.freeze({ get: () => undefined });
+
 /**
  * React hook for retrieving {@link ApiHolder}, an API catalog.
  *
@@ -27,7 +29,7 @@ import { NotImplementedError } from '@backstage/errors';
 export function useApiHolder(): ApiHolder {
   const versionedHolder = useVersionedContext<{ 1: ApiHolder }>('api-context');
   if (!versionedHolder) {
-    throw new NotImplementedError('API context is not available');
+    return emptyApiHolder;
   }
 
   const apiHolder = versionedHolder.atVersion(1);