From a1449b94bf26565f2539ad6c9b4847bcef9ca90b Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Fri, 13 Jan 2023 12:07:51 +0100
Subject: [PATCH] backend-plugin-api: tests for createSharedEnvironment + fixes

Co-authored-by: blam <ben@blam.sh>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 .../wiring/createSharedEnvironment.test.ts    | 99 +++++++++++++++++++
 .../src/wiring/createSharedEnvironment.ts     | 19 +++-
 2 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 packages/backend-plugin-api/src/wiring/createSharedEnvironment.test.ts

diff --git a/packages/backend-plugin-api/src/wiring/createSharedEnvironment.test.ts b/packages/backend-plugin-api/src/wiring/createSharedEnvironment.test.ts
new file mode 100644
index 0000000000..0f15941a45
--- /dev/null
+++ b/packages/backend-plugin-api/src/wiring/createSharedEnvironment.test.ts
@@ -0,0 +1,99 @@
+/*
+ * 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.
+ */
+
+import {
+  createServiceFactory,
+  createServiceRef,
+  ServiceFactoryOrFunction,
+} from '../services';
+import {
+  createSharedEnvironment,
+  InternalSharedBackendEnvironment,
+} from './createSharedEnvironment';
+
+const fooService = createServiceRef<string>({ id: 'foo', scope: 'root' });
+const fooFactory = createServiceFactory({
+  service: fooService,
+  deps: {},
+  async factory() {
+    return 'foo';
+  },
+});
+
+const barService = createServiceRef<number>({ id: 'bar', scope: 'root' });
+const barFactory = createServiceFactory({
+  service: barService,
+  deps: {},
+  async factory() {
+    return 0xba5;
+  },
+});
+
+describe('createSharedEnvironment', () => {
+  it('should create an empty shared environment', () => {
+    const env = createSharedEnvironment({});
+    expect(env).toBeDefined();
+    const internalEnv = env() as unknown as InternalSharedBackendEnvironment;
+    expect(internalEnv).toEqual({
+      version: 'v1',
+      services: undefined,
+    });
+  });
+
+  it('should create a shared environment with services', () => {
+    const env = createSharedEnvironment({
+      services: [fooFactory, barFactory()],
+    });
+    const internalEnv = env() as unknown as InternalSharedBackendEnvironment;
+    expect(internalEnv.version).toBe('v1');
+    expect(internalEnv.services?.length).toBe(2);
+    expect(internalEnv.services?.[0]?.service.id).toBe('foo');
+    expect(internalEnv.services?.[1]?.service.id).toBe('bar');
+  });
+
+  it('should create a shared environment with options', () => {
+    const env = createSharedEnvironment((options?: { withFoo?: boolean }) => {
+      const services = new Array<ServiceFactoryOrFunction>();
+      if (options?.withFoo) {
+        services.push(fooFactory());
+      }
+      services.push(barFactory);
+      return { services };
+    });
+    const internalEnv1 = env() as unknown as InternalSharedBackendEnvironment;
+    expect(internalEnv1.version).toBe('v1');
+    expect(internalEnv1.services?.length).toBe(1);
+    expect(internalEnv1.services?.[0]?.service.id).toBe('bar');
+
+    const internalEnv2 = env({
+      withFoo: true,
+    }) as unknown as InternalSharedBackendEnvironment;
+    expect(internalEnv2.version).toBe('v1');
+    expect(internalEnv2.services?.length).toBe(2);
+    expect(internalEnv2.services?.[0]?.service.id).toBe('foo');
+    expect(internalEnv2.services?.[1]?.service.id).toBe('bar');
+  });
+
+  it('should not allow duplicate service factories', () => {
+    expect(() =>
+      createSharedEnvironment({
+        services: [fooFactory, fooFactory()],
+      })(),
+    ).toThrow(
+      "Duplicate service implementations provided in shared environment for 'foo'",
+    );
+  });
+});
diff --git a/packages/backend-plugin-api/src/wiring/createSharedEnvironment.ts b/packages/backend-plugin-api/src/wiring/createSharedEnvironment.ts
index 05be5003bd..a353c01b9d 100644
--- a/packages/backend-plugin-api/src/wiring/createSharedEnvironment.ts
+++ b/packages/backend-plugin-api/src/wiring/createSharedEnvironment.ts
@@ -62,6 +62,23 @@ export function createSharedEnvironment<
       typeof sf === 'function' ? sf() : sf,
     );
 
-    return { services } as unknown as SharedBackendEnvironment;
+    const exists = new Set<string>();
+    const duplicates = new Set<string>();
+    for (const { service } of services ?? []) {
+      if (exists.has(service.id)) {
+        duplicates.add(service.id);
+      } else {
+        exists.add(service.id);
+      }
+    }
+
+    if (duplicates.size > 0) {
+      const dupStr = [...duplicates].map(id => `'${id}'`).join(', ');
+      throw new Error(
+        `Duplicate service implementations provided in shared environment for ${dupStr}`,
+      );
+    }
+
+    return { version: 'v1', services } as unknown as SharedBackendEnvironment;
   };
 }