frontend-app-api: add tests for extension overrides

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/frontend-app-api/src/wiring/createApp.test.tsx

@@ -16,6 +16,7 @@
 
 import {
   createExtension,
+  createExtensionOverrides,
   createPageExtension,
   createPlugin,
   createThemeExtension,
@@ -27,6 +28,13 @@ import React from 'react';
 import { createRouteRef } from '@backstage/core-plugin-api';
 import { createExtensionInstance } from './createExtensionInstance';
 
+const extBaseConfig = {
+  id: 'test',
+  attachTo: { id: 'root', input: 'default' },
+  output: {},
+  factory() {},
+};
+
 describe('createInstances', () => {
   it('throws an error when a root extension is parametrized', () => {
     const config = new MockConfigApi({
@@ -103,6 +111,26 @@ describe('createInstances', () => {
       "The following extensions are duplicated: The extension 'A' was provided 2 time(s) by the plugin 'A' and 1 time(s) by the plugin 'B', The extension 'B' was provided 2 time(s) by the plugin 'B'",
     );
   });
+
+  it('throws an error when duplicated extension overrides are detected', () => {
+    expect(() =>
+      createInstances({
+        config: new MockConfigApi({}),
+        features: [
+          createExtensionOverrides({
+            extensions: [
+              createExtension({ ...extBaseConfig, id: 'a' }),
+              createExtension({ ...extBaseConfig, id: 'a' }),
+              createExtension({ ...extBaseConfig, id: 'b' }),
+            ],
+          }),
+          createExtensionOverrides({
+            extensions: [createExtension({ ...extBaseConfig, id: 'b' })],
+          }),
+        ],
+      }),
+    ).toThrow('The following extensions had duplicate overrides: a, b');
+  });
 });
 
 describe('createApp', () => {

packages/frontend-app-api/src/wiring/parameters.test.ts

@@ -15,7 +15,11 @@
  */
 
 import { ConfigReader } from '@backstage/config';
-import { createPlugin, Extension } from '@backstage/frontend-plugin-api';
+import {
+  createExtensionOverrides,
+  createPlugin,
+  Extension,
+} from '@backstage/frontend-plugin-api';
 import { JsonValue } from '@backstage/types';
 import {
   expandShorthandExtensionParameters,
@@ -23,10 +27,14 @@ import {
   readAppExtensionParameters,
 } from './parameters';
 
-function makeExt(id: string, status: 'disabled' | 'enabled' = 'enabled') {
+function makeExt(
+  id: string,
+  status: 'disabled' | 'enabled' = 'enabled',
+  attachId: string = 'root',
+) {
   return {
     id,
-    attachTo: { id: 'root', input: 'default' },
+    attachTo: { id: attachId, input: 'default' },
     disabled: status === 'disabled',
   } as Extension<unknown>;
 }
@@ -144,6 +152,61 @@ describe('mergeExtensionParameters', () => {
       { extension: a, attachTo: { id: 'root', input: 'default' } },
     ]);
   });
+
+  it('should apply extension overrides', () => {
+    const a = makeExt('a');
+    const b = makeExt('b');
+    const plugin = createPlugin({ id: 'test', extensions: [a, b] });
+    const aOverride = makeExt('a', 'enabled', 'other');
+    const bOverride = makeExt('b', 'disabled', 'other');
+    const cOverride = makeExt('c');
+
+    const result = mergeExtensionParameters({
+      features: [
+        plugin,
+        createExtensionOverrides({
+          extensions: [aOverride, bOverride, cOverride],
+        }),
+      ],
+      builtinExtensions: [],
+      parameters: [],
+    });
+
+    expect(result.length).toBe(2);
+    expect(result[0].extension).toBe(aOverride);
+    expect(result[0].attachTo).toEqual({ id: 'other', input: 'default' });
+    expect(result[0].config).toEqual(undefined);
+    expect(result[0].source).toBe(plugin);
+
+    expect(result[1]).toEqual({
+      extension: cOverride,
+      attachTo: { id: 'root', input: 'default' },
+      config: undefined,
+      source: undefined,
+    });
+  });
+
+  it('should use order from configuration when rather than overrides', () => {
+    const a = makeExt('a', 'disabled');
+    const b = makeExt('b', 'disabled');
+    const c = makeExt('c', 'disabled');
+    const aOverride = makeExt('c', 'disabled');
+    const bOverride = makeExt('b', 'disabled');
+    const cOverride = makeExt('a', 'disabled');
+
+    const result = mergeExtensionParameters({
+      features: [
+        createPlugin({ id: 'test', extensions: [a, b, c] }),
+        createExtensionOverrides({
+          extensions: [cOverride, bOverride, aOverride],
+        }),
+      ],
+      builtinExtensions: [],
+      parameters: ['b', 'c', 'a'].map(id => ({ id, disabled: false })),
+    });
+
+    expect(result.map(r => r.extension.id)).toEqual(['b', 'c', 'a']);
+  });
 });
 
 describe('readAppExtensionParameters', () => {