feat: auto add modules to index.ts

Signed-off-by: Alper Altay <alper.altay@lego.com>

packages/cli/src/lib/new/factories/backendModule.test.ts

@@ -26,6 +26,14 @@ import {
 import { backendModule } from './backendModule';
 import { createMockDirectory } from '@backstage/backend-test-utils';
 
+const backendIndexTsContent = `
+import { createBackend } from '@backstage/backend-defaults';
+
+const backend = createBackend();
+
+backend.start();
+`;
+
 describe('backendModule factory', () => {
   const mockDir = createMockDirectory();
 
@@ -44,6 +52,9 @@ describe('backendModule factory', () => {
       packages: {
         backend: {
           'package.json': JSON.stringify({}),
+          src: {
+            'index.ts': backendIndexTsContent,
+          },
         },
       },
       plugins: {},
@@ -86,8 +97,20 @@ describe('backendModule factory', () => {
       'Installing:',
       `moving        plugins${sep}test-backend-module-tester-two`,
       'backend       adding dependency',
+      'backend       adding module',
     ]);
 
+    await expect(
+      fs.readFile(mockDir.resolve('packages/backend/src/index.ts'), 'utf8'),
+    ).resolves.toBe(`
+import { createBackend } from '@backstage/backend-defaults';
+
+const backend = createBackend();
+
+backend.add(import('backstage-plugin-test-backend-module-tester-two'));
+backend.start();
+`);
+
     await expect(
       fs.readJson(mockDir.resolve('packages/backend/package.json')),
     ).resolves.toEqual({

packages/cli/src/lib/new/factories/backendModule.ts

@@ -91,6 +91,31 @@ export const backendModule = createFactory<Options>({
       });
     }
 
+    await Task.forItem('backend', 'adding module', async () => {
+      const backendFilePath = paths.resolveTargetRoot(
+        'packages/backend/src/index.ts',
+      );
+      if (!(await fs.pathExists(backendFilePath))) {
+        return;
+      }
+
+      const content = await fs.readFile(backendFilePath, 'utf8');
+      const lines = content.split('\n');
+      const backendAddLine = `backend.add(import('${name}'));`;
+
+      const backendStartIndex = lines.findIndex(line =>
+        line.match(/backend.start/),
+      );
+
+      if (backendStartIndex !== -1) {
+        const [indentation] = lines[backendStartIndex].match(/^\s*/) ?? [];
+        lines.splice(backendStartIndex, 0, indentation + backendAddLine);
+
+        const newContent = lines.join('\n');
+        await fs.writeFile(backendFilePath, newContent, 'utf8');
+      }
+    });
+
     if (options.owner) {
       await addCodeownersEntry(`/plugins/${dirName}`, options.owner);
     }