feat: default to enableOptionalDependencies: true in metro config (#1350)

* feat: default to enableOptionalDependencies: true in metro config

* feat: add test for getDefaultConfig

* simplify type

Co-authored-by: Michał Pierzchała <[email protected]>

Author: brentvatne

packages/cli/src/tools/__tests__/loadMetroConfig-test.ts

@@ -0,0 +1,16 @@
+import {getDefaultConfig} from '../loadMetroConfig';
+
+jest.mock('fs');
+jest.mock('path');
+
+describe('getDefaultConfig', () => {
+  it('should preserve transformer.allowOptionalDependencies=true when overriding other transformer options', async () => {
+    const config = getDefaultConfig({
+      root: '/',
+      reactNativePath: '',
+      platforms: {},
+    });
+
+    expect(config.transformer.allowOptionalDependencies).toBe(true);
+  });
+});

packages/cli/src/tools/loadMetroConfig.ts

@@ -20,6 +20,11 @@ const INTERNAL_CALLSITES_REGEX = new RegExp(
   ].join('|'),
 );
 
+type ConfigLoadingContext = Pick<
+  Config,
+  'root' | 'reactNativePath' | 'platforms'
+>;
+
 export interface MetroConfig {
   resolver: {
     resolveRequest?: (
@@ -43,6 +48,7 @@ export interface MetroConfig {
     customizeFrame: (frame: {file: string | null}) => {collapse: boolean};
   };
   transformer: {
+    allowOptionalDependencies?: boolean;
     babelTransformerPath: string;
     assetRegistryPath: string;
     assetPlugins?: Array<string>;
@@ -55,7 +61,7 @@ export interface MetroConfig {
 /**
  * Default configuration
  */
-export const getDefaultConfig = (ctx: Config): MetroConfig => {
+export const getDefaultConfig = (ctx: ConfigLoadingContext): MetroConfig => {
   const outOfTreePlatforms = Object.keys(ctx.platforms).filter(
     (platform) => ctx.platforms[platform].npmPackageName,
   );
@@ -106,6 +112,7 @@ export const getDefaultConfig = (ctx: Config): MetroConfig => {
       },
     },
     transformer: {
+      allowOptionalDependencies: true,
       babelTransformerPath: require.resolve(
         'metro-react-native-babel-transformer',
       ),
@@ -135,7 +142,7 @@ export interface ConfigOptionsT {
  * This allows the CLI to always overwrite the file settings.
  */
 export default function load(
-  ctx: Config,
+  ctx: ConfigLoadingContext,
   options?: ConfigOptionsT,
 ): Promise<MetroConfig> {
   const defaultConfig = getDefaultConfig(ctx);