test(acr): address review — pin to the release manifest, and actually render

Five review findings.

@backstage/frontend-test-utils was added as ^0.6.3 while this workspace pins
Backstage 1.52.0, whose manifest ships 0.6.1. The caret pulled a second
frontend-plugin-api/core-components tree: 446 lines of lockfile and
`yarn dedupe --check` reporting 15 dedupable packages, which
scripts/ci/verify-lockfile-duplicates.js runs in CI. `^0.6.1` does not help —
yarn still resolves to 0.6.3 — so it is pinned exactly, and the lockfile delta
drops to 37 lines with a clean dedupe.

The file claimed "the only render here is through the extension itself" and then
never rendered: reactElement() was never called, so the blueprint's dynamic
import was untested and renaming the component left every assertion green. There
is now a real render through the extension, and pointing the loader at the wrong
component turns exactly one test red.

Copyright year corrected to 2026, per AGENTS.md.

The changeset described internal test scaffolding; AGENTS.md asks for
adopter-facing plain language.

Six single-assertion tests consolidated into three thorough ones, per AGENTS.md.
The assertion on the plugin's $$type went with them — it is a Backstage-internal
marker that no change to this plugin can affect, so it could only ever go red on
an unrelated framework upgrade.

All six mutations still caught, one test each: title, path, filter, extension
removed from the plugin, plugin id renamed, and now the loader's import target.

Signed-off-by: Gustavo Lira e Silva <guga.java@gmail.com>

Author: gustavolira

workspaces/acr/.changeset/acr-alpha-wiring-tests.md

@@ -2,4 +2,4 @@
 '@backstage-community/plugin-acr': patch
 ---
 
-Add tests for the new frontend system wiring: the entity content's title, route path and entity filter, and that the plugin registers both extensions. Test-only; no runtime change.
+Added tests covering the plugin's new frontend system entity content. No change in behaviour.

workspaces/acr/plugins/acr/package.json

@@ -64,7 +64,7 @@
     "@axe-core/playwright": "^4.11.0",
     "@backstage/cli": "^0.36.3",
     "@backstage/dev-utils": "^1.1.24",
-    "@backstage/frontend-test-utils": "^0.6.3",
+    "@backstage/frontend-test-utils": "0.6.1",
     "@backstage/test-utils": "^1.7.19",
     "@playwright/test": "1.61.1",
     "@testing-library/jest-dom": "6.9.1",

workspaces/acr/plugins/acr/src/alpha.test.tsx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2025 The Backstage Authors
+ * Copyright 2026 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.
@@ -15,85 +15,76 @@
  */
 import { Entity } from '@backstage/catalog-model';
 import { coreExtensionData } from '@backstage/frontend-plugin-api';
-import { createExtensionTester } from '@backstage/frontend-test-utils';
+import {
+  createExtensionTester,
+  renderInTestApp,
+} from '@backstage/frontend-test-utils';
+import { EntityProvider } from '@backstage/plugin-catalog-react';
 import { EntityContentBlueprint } from '@backstage/plugin-catalog-react/alpha';
+import { screen } from '@testing-library/react';
 
+import { AzureContainerRegistryApiRef } from './api';
+import { mockAcrTagsData } from './__fixtures__/acrTagsObject';
 import { mockEntity } from './__fixtures__/mockEntity';
 import nfsPlugin, { acrImagesEntityContent } from './alpha';
+import { TagsResponse } from './types';
+
+/** The fixture carries ISO strings where the API returns Dates. */
+const tagsResponse: TagsResponse = {
+  imageName: mockAcrTagsData.imageName,
+  registry: mockAcrTagsData.registry,
+  tags: mockAcrTagsData.tags.map(tag => ({
+    ...tag,
+    createdTime: new Date(tag.createdTime),
+    lastUpdateTime: new Date(tag.lastUpdateTime),
+  })),
+};
 
-/**
- * These assert the plugin's *wiring* under the new frontend system: the title the
- * catalog will print on the tab, the path it mounts at, and the entities it shows
- * for. Under the new frontend system those are declared by the extension rather
- * than configured by the app, so an end-to-end test that clicks the tab is really
- * checking these three facts through a browser and a deployment.
- *
- * Rendering is covered a layer down by AcrImagesEntityContent.test.tsx; the only
- * render here is through the extension itself, which is the part that test cannot
- * reach.
- */
 describe('alpha (new frontend system)', () => {
-  it('declares the tab title the catalog will render', () => {
+  it('declares the tab the catalog renders, and which entities get it', () => {
     const tester = createExtensionTester(acrImagesEntityContent);
 
     expect(tester.get(EntityContentBlueprint.dataRefs.title)).toBe(
       'ACR images',
     );
-  });
-
-  it('declares the path the tab mounts at', () => {
-    const tester = createExtensionTester(acrImagesEntityContent);
-
     expect(tester.get(coreExtensionData.routePath)).toBe('acr-images');
-  });
 
-  describe('the filter that decides which entities show the tab', () => {
-    const filter = () => {
-      const fn = createExtensionTester(acrImagesEntityContent).get(
-        EntityContentBlueprint.dataRefs.filterFunction,
-      );
-      // The blueprint makes this output optional, and an extension without it
-      // shows the tab on every entity in the catalog — so its absence is a
-      // defect rather than a variant, and worth failing on by name.
-      if (!fn)
-        throw new Error('acrImagesEntityContent declares no entity filter');
-      return fn;
+    const filter = tester.get(EntityContentBlueprint.dataRefs.filterFunction);
+    if (!filter) throw new Error('the entity content declares no filter');
+    const withoutAnnotation: Entity = {
+      ...mockEntity,
+      metadata: { ...mockEntity.metadata, annotations: {} },
     };
+    expect(filter(mockEntity)).toBe(true);
+    expect(filter(withoutAnnotation)).toBe(false);
+  });
 
-    it('shows the tab for an entity annotated with a repository name', () => {
-      expect(filter()(mockEntity)).toBe(true);
-    });
-
-    it('hides the tab for an entity with no ACR annotation', () => {
-      const withoutAnnotation: Entity = {
-        ...mockEntity,
-        metadata: { ...mockEntity.metadata, annotations: {} },
-      };
-
-      expect(filter()(withoutAnnotation)).toBe(false);
-    });
+  it('is registered by the plugin under the id the app resolves', () => {
+    // Not covered by anything else here: createExtensionTester instantiates an
+    // extension in isolation, so removing it from the plugin's `extensions`
+    // leaves every other assertion in this file green while the tab disappears.
+    expect(
+      nfsPlugin.getExtension('entity-content:acr/acrImagesEntityContent'),
+    ).toBeDefined();
+    expect(nfsPlugin.getExtension('api:acr/acrApi')).toBeDefined();
   });
 
-  /**
-   * Not optional, and not covered by any assertion above.
-   *
-   * `createExtensionTester` instantiates an extension in isolation, so it cannot
-   * see whether the plugin actually registers it. Deleting `acrImagesEntityContent`
-   * from the plugin's `extensions` array leaves every test above green while the
-   * tab disappears from a real app — and because a plugin that contributes nothing
-   * still boots cleanly, nothing else would report it either.
-   */
-  describe('registration', () => {
-    it('registers the entity content and the API on the plugin', () => {
-      expect(
-        nfsPlugin.getExtension('entity-content:acr/acrImagesEntityContent'),
-      ).toBeDefined();
-      expect(nfsPlugin.getExtension('api:acr/acrApi')).toBeDefined();
-    });
+  it('renders the registry through the extension', async () => {
+    // Through the blueprint's own loader, which the component's own test cannot
+    // reach — renaming the component leaves the assertions above green.
+    renderInTestApp(
+      <EntityProvider entity={mockEntity}>
+        {createExtensionTester(acrImagesEntityContent).reactElement()}
+      </EntityProvider>,
+      {
+        apis: [
+          [AzureContainerRegistryApiRef, { getTags: async () => tagsResponse }],
+        ],
+      },
+    );
 
-    it('is a frontend plugin the app can install, under the expected id', () => {
-      expect(nfsPlugin.$$type).toBe('@backstage/FrontendPlugin');
-      expect(nfsPlugin.pluginId).toBe('acr');
-    });
+    expect(
+      await screen.findByText(tagsResponse.tags[0].name),
+    ).toBeInTheDocument();
   });
 });