diff --git a/zeppelin-web-angular/src/app/share/react-mount/react-mount.directive.testbed.spec.ts b/zeppelin-web-angular/src/app/share/react-mount/react-mount.directive.testbed.spec.ts
new file mode 100644
index 00000000000..17e621ab33c
--- /dev/null
+++ b/zeppelin-web-angular/src/app/share/react-mount/react-mount.directive.testbed.spec.ts
@@ -0,0 +1,95 @@
+/*
+ * 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.
+ */
+
+import { Component, NgZone, provideZoneChangeDetection } from '@angular/core';
+import { ComponentFixture, TestBed } from '@angular/core/testing';
+import { Mock, beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { ReactExposedModule, ReactMountHandle, ReactProps } from './react-mount-handle';
+import { ReactMountDirective } from './react-mount.directive';
+import { ReactRemoteLoaderService } from './react-remote-loader.service';
+
+@Component({
+  standalone: false,
+  template: `
+    <div [zeppelin-react-mount]="module" [reactProps]="reactProps"></div>
+  `
+})
+class HostComponent {
+  module = 'paragraph-footer';
+  reactProps: ReactProps = { paragraphId: 'p1' };
+}
+
+/**
+ * Companion to react-mount.directive.spec.ts, which drives the directive by
+ * hand. Going through TestBed puts the decorator metadata itself under test:
+ * the template bindings and constructor injection have to resolve to get here.
+ */
+describe('ReactMountDirective (TestBed)', () => {
+  let fixture: ComponentFixture<HostComponent>;
+  let handle: ReactMountHandle;
+  let mountedElements: HTMLElement[];
+  let mountZoneStates: boolean[];
+  let loadModule: Mock<(module: string) => Promise<ReactExposedModule>>;
+
+  beforeEach(() => {
+    mountedElements = [];
+    mountZoneStates = [];
+    handle = { update: vi.fn(), unmount: vi.fn() };
+    const remote: ReactExposedModule = {
+      mount: (element: HTMLElement) => {
+        mountedElements.push(element);
+        mountZoneStates.push(NgZone.isInAngularZone());
+        return handle;
+      }
+    };
+    loadModule = vi.fn(async () => remote);
+
+    TestBed.configureTestingModule({
+      declarations: [HostComponent, ReactMountDirective],
+      // TestBed defaults to zoneless, which would make the zone assertions
+      // below pass vacuously. main.ts bootstraps with zones, so mirror it.
+      providers: [provideZoneChangeDetection(), { provide: ReactRemoteLoaderService, useValue: { loadModule } }]
+    });
+
+    fixture = TestBed.createComponent(HostComponent);
+  });
+
+  it('mounts the remote on the host element outside the Angular zone', async () => {
+    fixture.detectChanges();
+    await fixture.whenStable();
+
+    expect(loadModule).toHaveBeenCalledWith('paragraph-footer');
+    expect(mountedElements).toEqual([fixture.nativeElement.querySelector('div')]);
+    expect(mountZoneStates).toEqual([false]);
+  });
+
+  it('forwards later reactProps changes to the mount handle', async () => {
+    fixture.detectChanges();
+    await fixture.whenStable();
+
+    fixture.componentInstance.reactProps = { paragraphId: 'p2' };
+    fixture.detectChanges();
+
+    expect(handle.update).toHaveBeenCalledWith({ paragraphId: 'p2' });
+    expect(loadModule).toHaveBeenCalledOnce();
+  });
+
+  it('unmounts when the host component is destroyed', async () => {
+    fixture.detectChanges();
+    await fixture.whenStable();
+
+    fixture.destroy();
+
+    expect(handle.unmount).toHaveBeenCalledOnce();
+  });
+});
diff --git a/zeppelin-web-angular/test/test-setup.ts b/zeppelin-web-angular/test/test-setup.ts
index 7d0997c797d..ae120021fd3 100644
--- a/zeppelin-web-angular/test/test-setup.ts
+++ b/zeppelin-web-angular/test/test-setup.ts
@@ -11,3 +11,16 @@
  */
 
 import 'zone.js';
+// The pair src/polyfills.ts loads for the application. Without Reflect.metadata
+// the emitted `__metadata` helper is a silent no-op and injection fails NG0202.
+import 'core-js/es7/reflect';
+
+import { getTestBed } from '@angular/core/testing';
+import { BrowserTestingModule, platformBrowserTesting } from '@angular/platform-browser/testing';
+import { afterEach } from 'vitest';
+
+getTestBed().initTestEnvironment(BrowserTestingModule, platformBrowserTesting());
+
+// Vitest globals are disabled, so Angular cannot install its own reset hook and
+// the test module stays locked after the first spec instantiates it.
+afterEach(() => getTestBed().resetTestingModule());
diff --git a/zeppelin-web-angular/vitest.shell.config.mts b/zeppelin-web-angular/vitest.shell.config.mts
index 4799e537f6e..ed931317fcf 100644
--- a/zeppelin-web-angular/vitest.shell.config.mts
+++ b/zeppelin-web-angular/vitest.shell.config.mts
@@ -13,6 +13,15 @@
 import { defineConfig } from 'vitest/config';
 
 export default defineConfig({
+  // oxc does not apply the decorator options from tsconfig.base.json to specs,
+  // which src/tsconfig.json excludes. Undeclared, a decorated spec fails to
+  // parse with "Invalid or unexpected token".
+  oxc: {
+    decorator: {
+      emitDecoratorMetadata: true,
+      legacy: true
+    }
+  },
   test: {
     environment: 'jsdom',
     include: ['src/**/*.spec.ts'],