Allow configuring Babel runtime via caller in @react-native/babel-preset (#57974)

packages/react-native-babel-preset/src/__tests__/transform-runtime-caller-test.js

@@ -0,0 +1,130 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+'use strict';
+
+// $FlowExpectedError[untyped-import] - Preset is untyped
+const preset = require('../index');
+const babel = require('@babel/core');
+
+const MOCK_FILENAME = '/absolute/path/to/input.js';
+
+function transformWithCaller(
+  code: string,
+  options: {[string]: unknown},
+  caller: {
+    enableBabelRuntime?: boolean | string,
+    babelRuntimeModuleName?: string,
+  },
+): string | null {
+  const result = babel.transformSync(code, {
+    babelrc: false,
+    configFile: false,
+    filename: MOCK_FILENAME,
+    presets: [[preset, options]],
+    caller: {...caller, name: 'test'},
+    sourceMaps: false,
+    compact: false,
+  });
+  return result?.code ?? null;
+}
+
+describe('babel runtime caller options', () => {
+  it('uses caller-provided babelRuntimeModuleName for runtime helpers', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {babelRuntimeModuleName: '@react-native/babel-runtime'},
+    );
+    expect(result).toContain(
+      '@react-native/babel-runtime/helpers/objectWithoutProperties',
+    );
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+
+  it('options babelRuntimeModuleName takes precedence over caller', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false, babelRuntimeModuleName: '@from/options'},
+      {babelRuntimeModuleName: '@from/caller'},
+    );
+    expect(result).toContain('@from/options/helpers/objectWithoutProperties');
+    expect(result).not.toContain('@from/caller');
+  });
+
+  it('uses caller-provided enableBabelRuntime version to select the helper interop', () => {
+    // A default import triggers the `interopRequireDefault` helper, whose import
+    // form depends on the runtime version. Modern versions append `.default`.
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('options enableBabelRuntime takes precedence over caller', () => {
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(
+      code,
+      {dev: false, enableBabelRuntime: '7.0.0'},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    // Options version (7.0.0) uses the legacy interop form without `.default`,
+    // overriding the caller version (7.25.0) that would produce `.default`.
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault")',
+    );
+    expect(result).not.toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('has no effect when caller options are absent', () => {
+    const code = "import foo from './foo';\nfoo();";
+    const result = transformWithCaller(code, {dev: false}, {});
+    // Default runtime version uses the legacy interop form (no `.default`).
+    expect(result).toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault")',
+    );
+    expect(result).not.toContain(
+      'require("@babel/runtime/helpers/interopRequireDefault").default',
+    );
+  });
+
+  it('does not add the runtime plugin when caller disables enableBabelRuntime', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false},
+      {
+        enableBabelRuntime: false,
+        babelRuntimeModuleName: '@react-native/babel-runtime',
+      },
+    );
+    expect(result).not.toContain('@react-native/babel-runtime');
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+
+  it('options enableBabelRuntime false takes precedence over caller true', () => {
+    const code = 'const {a, ...rest} = obj;';
+    const result = transformWithCaller(
+      code,
+      {dev: false, enableBabelRuntime: false},
+      {enableBabelRuntime: '7.25.0'},
+    );
+    expect(result).not.toContain('@babel/runtime/helpers');
+  });
+});

packages/react-native-babel-preset/src/configs/main.js

@@ -40,10 +40,16 @@ function isFirstParty(fileName) {
   );
 }
 
-// Called by Babel whenever caller information changes between transform calls
-// for a given config. If the return value changes, Babel re-evaluates
-// getPreset, which is otherwise cached based on `options`. This must be pure,
-// and should be cheap.
+/**
+ * BEGIN BABEL CALLER GETTERS
+ * Called by Babel whenever caller information changes between transform calls
+ * for a given config. If the return value changes, Babel re-evaluates
+ * getPreset, which is otherwise cached based on `options`.
+ *
+ * These functions must be pure and should be cheap.
+ **/
+
+// Target transform profile, influencing which plugins are active
 function getTransformProfile(caller) {
   return caller?.unstable_transformProfile ?? 'hermes-stable';
 }
@@ -60,6 +66,20 @@ function getInlinePlatform(caller) {
   return caller?.inlinePlatform ?? false;
 }
 
+// A boolean to toggle @babel/plugin-transform-runtime, or a string to pin
+// a specific @babel/runtime version.
+function getEnableBabelRuntime(caller) {
+  return caller?.enableBabelRuntime;
+}
+
+// Reads the caller-provided @babel/runtime module name that helpers are imported
+// from.
+function getBabelRuntimeModuleName(caller) {
+  return caller?.babelRuntimeModuleName;
+}
+
+/* END BABEL CALLER GETTERS */
+
 // use `this.foo = bar` instead of `this.defineProperty('foo', ...)`
 const loose = true;
 
@@ -230,16 +250,31 @@ const getPreset = (src, options, babel) => {
     ]);
   }
 
-  if (!options || options.enableBabelRuntime !== false) {
-    // Allows configuring a specific runtime version to optimize output
-    const isVersion = typeof options?.enableBabelRuntime === 'string';
+  // `enableBabelRuntime` (a boolean toggle or a string @babel/runtime version to
+  // pin) and `babelRuntimeModuleName` (the module helpers are imported from) may
+  // be provided via options or, for programmatic callers such as Metro, via
+  // Babel caller data. Options take precedence over caller data, consistent with
+  // the other options resolved here.
+  const enableBabelRuntime =
+    options?.enableBabelRuntime ?? babel?.caller(getEnableBabelRuntime) ?? true;
+
+  if (enableBabelRuntime !== false) {
+    // A string value pins a specific runtime version to optimize output.
+    const isVersion = typeof enableBabelRuntime === 'string';
+
+    const babelRuntimeModuleName =
+      options?.babelRuntimeModuleName ??
+      babel?.caller(getBabelRuntimeModuleName);
 
     extraPlugins.push([
       require('@babel/plugin-transform-runtime'),
       {
         helpers: true,
         regenerator: enableRegenerator,
-        ...(isVersion && {version: options.enableBabelRuntime}),
+        ...(isVersion && {version: enableBabelRuntime}),
+        ...(babelRuntimeModuleName != null && {
+          moduleName: babelRuntimeModuleName,
+        }),
       },
     ]);
   } else if (enableRegenerator) {