diff --git a/packages/backend-app-api/src/wiring/ServiceRegistry.test.ts b/packages/backend-app-api/src/wiring/ServiceRegistry.test.ts
new file mode 100644
index 0000000000..438a11130f
--- /dev/null
+++ b/packages/backend-app-api/src/wiring/ServiceRegistry.test.ts
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2022 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.
+ */
+
+import {
+  createServiceRef,
+  createServiceFactory,
+} from '@backstage/backend-plugin-api';
+import { ServiceRegistry } from './ServiceRegistry';
+
+const ref1 = createServiceRef<{ x: number; pluginId: string }>({
+  id: '1',
+});
+const sf1 = createServiceFactory({
+  service: ref1,
+  deps: {},
+  factory: async ({}) => {
+    return async pluginId => {
+      return { x: 1, pluginId };
+    };
+  },
+});
+
+const ref2 = createServiceRef<{ x: number; pluginId: string }>({
+  id: '2',
+});
+const sf2 = createServiceFactory({
+  service: ref2,
+  deps: {},
+  factory: async ({}) => {
+    return async pluginId => {
+      return { x: 2, pluginId };
+    };
+  },
+});
+const sf2b = createServiceFactory({
+  service: ref2,
+  deps: {},
+  factory: async ({}) => {
+    return async pluginId => {
+      return { x: 22, pluginId };
+    };
+  },
+});
+
+describe('ServiceRegistry', () => {
+  it('should return undefined if there is no factory defined', async () => {
+    const registry = new ServiceRegistry([]);
+    expect(registry.get(ref1)).toBe(undefined);
+  });
+
+  it('should return a factory for a registered ref', async () => {
+    const registry = new ServiceRegistry([sf1]);
+    const factory = registry.get(ref1)!;
+    expect(factory).toEqual(expect.any(Function));
+    await expect(factory('catalog')).resolves.toEqual({
+      x: 1,
+      pluginId: 'catalog',
+    });
+    await expect(factory('scaffolder')).resolves.toEqual({
+      x: 1,
+      pluginId: 'scaffolder',
+    });
+    expect(await factory('catalog')).toBe(await factory('catalog'));
+  });
+
+  it('should handle multiple factories with different serviceRefs', async () => {
+    const registry = new ServiceRegistry([sf1, sf2]);
+    const factory1 = registry.get(ref1)!;
+    const factory2 = registry.get(ref2)!;
+    expect(factory1).toEqual(expect.any(Function));
+    expect(factory2).toEqual(expect.any(Function));
+    await expect(factory1('catalog')).resolves.toEqual({
+      x: 1,
+      pluginId: 'catalog',
+    });
+    await expect(factory2('catalog')).resolves.toEqual({
+      x: 2,
+      pluginId: 'catalog',
+    });
+    expect(await factory1('catalog')).not.toBe(await factory2('catalog'));
+  });
+
+  it('should use the last factory for each ref', async () => {
+    const registry = new ServiceRegistry([sf2, sf2b]);
+    const factory2 = registry.get(ref2)!;
+    await expect(factory2('catalog')).resolves.toEqual({
+      x: 22,
+      pluginId: 'catalog',
+    });
+  });
+});