From 888748f10b54984e2710020dd1f16a0fa32e48dc Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Tue, 5 Sep 2023 16:58:37 +0200
Subject: [PATCH] frontend-app-api: add discovery tests

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 packages/app-next-example-plugin/src/index.ts |  11 +-
 .../src/wiring/discovery.test.ts              | 115 ++++++++++++++++++
 2 files changed, 117 insertions(+), 9 deletions(-)
 create mode 100644 packages/frontend-app-api/src/wiring/discovery.test.ts

diff --git a/packages/app-next-example-plugin/src/index.ts b/packages/app-next-example-plugin/src/index.ts
index 94858a71a5..dae1eea379 100644
--- a/packages/app-next-example-plugin/src/index.ts
+++ b/packages/app-next-example-plugin/src/index.ts
@@ -15,13 +15,6 @@
  */
 
 export { examplePlugin } from './plugin';
-// TODO: This should be an extension created & exported in the `plugin.tsx`
-// YEAHHH most likely but there's no api(output) for it yet.
-export { ExampleSidebarItem } from './ExampleSidebarItem';
 
-export const a1 = null;
-export const a2 = false;
-export const a3 = true;
-export const a4 = Symbol('b');
-export const a5 = 3;
-export const a6 = [];
+// TODO: This should be an extension created & exported in the `plugin.tsx`
+export { ExampleSidebarItem } from './ExampleSidebarItem';
diff --git a/packages/frontend-app-api/src/wiring/discovery.test.ts b/packages/frontend-app-api/src/wiring/discovery.test.ts
new file mode 100644
index 0000000000..249f9dcea9
--- /dev/null
+++ b/packages/frontend-app-api/src/wiring/discovery.test.ts
@@ -0,0 +1,115 @@
+/*
+ * 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 { createPlugin } from '@backstage/frontend-plugin-api';
+import { getAvailablePlugins } from './discovery';
+
+const globalSpy = jest.fn();
+Object.defineProperty(global, '__@backstage/discovered__', {
+  get: globalSpy,
+});
+
+describe('getAvailablePlugins', () => {
+  afterEach(jest.resetAllMocks);
+
+  it('should discover nothing with undefined global', () => {
+    expect(getAvailablePlugins()).toEqual([]);
+  });
+
+  it('should discover nothing with empty global', () => {
+    globalSpy.mockReturnValue({
+      modules: [],
+    });
+    expect(getAvailablePlugins()).toEqual([]);
+  });
+
+  it('should discover a plugin', () => {
+    const testPlugin = createPlugin({ id: 'test' });
+    globalSpy.mockReturnValue({
+      modules: [
+        {
+          module: {
+            testPlugin,
+          },
+        },
+      ],
+    });
+    expect(getAvailablePlugins()).toEqual([testPlugin]);
+  });
+
+  it('should ignore garbage', () => {
+    const testPlugin = createPlugin({ id: 'test' });
+    globalSpy.mockReturnValue({
+      modules: [
+        {
+          module: {
+            testPlugin,
+            a: 1,
+            b: null,
+            c: undefined,
+            d: Symbol('wat'),
+            e: () => {},
+            f: [],
+            g: {},
+            h: 'h',
+            i: NaN,
+            j: Infinity,
+            k: -Infinity,
+            l: new Date(),
+            m: new RegExp('wat'),
+            n: new Error('wat'),
+            o: new Map(),
+            p: new Set(),
+            q: new WeakMap(),
+            r: new WeakSet(),
+            s: new ArrayBuffer(1),
+            t: new DataView(new ArrayBuffer(1)),
+            u: false,
+            v: true,
+            w: 0,
+          },
+        },
+      ],
+    });
+    expect(getAvailablePlugins()).toEqual([testPlugin]);
+  });
+
+  it('should discover multiple plugins', () => {
+    const test1Plugin = createPlugin({ id: 'test1' });
+    const test2Plugin = createPlugin({ id: 'test2' });
+    const test3Plugin = createPlugin({ id: 'test3' });
+    globalSpy.mockReturnValue({
+      modules: [
+        {
+          module: {
+            test1Plugin,
+            test2Plugin,
+          },
+        },
+        {
+          module: {
+            test3Plugin,
+          },
+        },
+      ],
+    });
+    expect(getAvailablePlugins()).toEqual([
+      test1Plugin,
+      test2Plugin,
+      test3Plugin,
+    ]);
+  });
+});