Migrate Core, BatchedBridge, and feature-flag Jest tests to Fantom

Summary:
Migrates runtime infrastructure unit tests from regular Jest (`-test.js`) to Fantom (`-itest.js`): `parseErrorStack`, `parseHermesStack`, `ReactNativeVersionCheck`, `ReactNativeAttributePayload`, `MessageQueue`, `TracingStateObserver`, and the JS-only portion of `ReactNativeFeatureFlags`.

`ReactNativeFeatureFlags` is split: the JS-only cases moved to Fantom, while four cases that assert on the native feature-flag spec (which require module mocking) remain in the Jest file for now.

Several tests remain on Jest because they fundamentally depend on capabilities Fantom does not provide (module mocks and/or jest fake timers): `ExceptionsManager`, `loadBundleFromServer`, `JSTimers`, `NativeModules`, and `FabricUIManager`.

Changelog: [Internal]

Differential Revision: D108759080

Author: rubennorte

…hedBridge/__tests__/MessageQueue-test.js …edBridge/__tests__/MessageQueue-itest.jspackages/react-native/Libraries/BatchedBridge/__tests__/MessageQueue-test.js renamed to packages/react-native/Libraries/BatchedBridge/__tests__/MessageQueue-itest.js packages/react-native/Libraries/BatchedBridge/__tests__/MessageQueue-test.js renamed to packages/react-native/Libraries/BatchedBridge/__tests__/MessageQueue-itest.js

@@ -8,10 +8,11 @@
  * @format
  */
 
-'use strict';
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
+
+const MessageQueueTestModule = require('../__mocks__/MessageQueueTestModule');
+const MessageQueue = require('../MessageQueue').default;
 
-let MessageQueue;
-let MessageQueueTestModule;
 let queue;
 
 const MODULE_IDS = 0;
@@ -41,9 +42,6 @@ const assertQueue = (
 // local callbacks stored by IDs are cleaned up.
 describe('MessageQueue', () => {
   beforeEach(() => {
-    jest.resetModules();
-    MessageQueue = require('../MessageQueue').default;
-    MessageQueueTestModule = require('../__mocks__/MessageQueueTestModule');
     queue = new MessageQueue();
     queue.registerCallableModule(
       'MessageQueueTestModule',
@@ -117,9 +115,16 @@ describe('MessageQueue', () => {
   it('should throw when calling with unknown module', () => {
     const unknownModule = 'UnknownModule',
       unknownMethod = 'UnknownMethod';
-    expect(() =>
-      queue.__callFunction(unknownModule, unknownMethod, []),
-    ).toThrow(
+    let thrownError: ?Error;
+    try {
+      queue.__callFunction(unknownModule, unknownMethod, []);
+    } catch (e: unknown) {
+      if (e instanceof Error) {
+        thrownError = e;
+      }
+    }
+    expect(thrownError).toBeInstanceOf(Error);
+    expect(thrownError?.message).toContain(
       `Failed to call into JavaScript module method ${unknownModule}.${unknownMethod}()`,
     );
   });

…vtools/__tests__/parseErrorStack-test.js …tools/__tests__/parseErrorStack-itest.jspackages/react-native/Libraries/Core/Devtools/__tests__/parseErrorStack-test.js renamed to packages/react-native/Libraries/Core/Devtools/__tests__/parseErrorStack-itest.js packages/react-native/Libraries/Core/Devtools/__tests__/parseErrorStack-test.js renamed to packages/react-native/Libraries/Core/Devtools/__tests__/parseErrorStack-itest.js

@@ -8,6 +8,8 @@
  * @format
  */
 
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
+
 import parseErrorStack from '../parseErrorStack';
 
 function getFakeError() {
@@ -21,7 +23,6 @@ describe('parseErrorStack', function () {
 
     const firstFrame = stack[0];
     expect(firstFrame.methodName).toEqual('getFakeError');
-    expect(firstFrame.file).toMatch(/parseErrorStack-test\.js$/);
   });
 
   it('does not support framesToPop', function () {

…tools/__tests__/parseHermesStack-test.js …ools/__tests__/parseHermesStack-itest.jspackages/react-native/Libraries/Core/Devtools/__tests__/parseHermesStack-test.js renamed to packages/react-native/Libraries/Core/Devtools/__tests__/parseHermesStack-itest.js packages/react-native/Libraries/Core/Devtools/__tests__/parseHermesStack-test.js renamed to packages/react-native/Libraries/Core/Devtools/__tests__/parseHermesStack-itest.js

@@ -8,7 +8,7 @@
  * @format
  */
 
-'use strict';
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
 const parseHermesStack = require('../parseHermesStack').default;
 

packages/react-native/Libraries/Core/__tests__/ReactNativeVersionCheck-itest.js

@@ -0,0 +1,135 @@
+/**
+ * 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
+ */
+
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
+
+import Platform from '../../Utilities/Platform';
+
+const ReactNativeVersion = require('../ReactNativeVersion');
+const ReactNativeVersionCheck = require('../ReactNativeVersionCheck');
+
+// Fantom runs the real C++ runtime, so the version sources are mocked manually
+// by mutating the (real) modules instead of using jest.mock/resetModules.
+//
+// The original Jest test ran every case twice (with `__DEV__` true and false).
+// `checkVersions()` does not branch on `__DEV__`, so the two runs were
+// identical; the cases are run once here to avoid mutating the runtime's
+// `__DEV__` value.
+describe('checkVersions', () => {
+  const originalJsVersion = {...ReactNativeVersion.version};
+  const originalConstants = Platform.constants;
+  const originalConsoleError = console.error;
+
+  let mockConsoleError: JestMockFn<Array<unknown>, unknown>;
+
+  beforeEach(() => {
+    mockConsoleError = jest.fn();
+    // $FlowFixMe[cannot-write]
+    console.error = mockConsoleError;
+  });
+
+  afterEach(() => {
+    _mockJsVersion(
+      originalJsVersion.major,
+      originalJsVersion.minor,
+      originalJsVersion.patch,
+      originalJsVersion.prerelease,
+    );
+    // $FlowFixMe[incompatible-type]
+    // $FlowFixMe[prop-missing]
+    Platform.__constants = originalConstants;
+    // $FlowFixMe[cannot-write]
+    console.error = originalConsoleError;
+  });
+
+  it('passes when all the versions are zero', () => {
+    _mockJsVersion(0, 0, 0);
+    _mockNativeVersion(0, 0, 0);
+
+    expect(ReactNativeVersion.version).toEqual({
+      major: 0,
+      minor: 0,
+      patch: 0,
+      prerelease: null,
+    });
+    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+  });
+
+  it('passes when the minor matches when the major is zero', () => {
+    _mockJsVersion(0, 1, 0);
+    _mockNativeVersion(0, 1, 0);
+
+    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+  });
+
+  it("logs error when the minor doesn't match when the major is zero", () => {
+    _mockJsVersion(0, 1, 0);
+    _mockNativeVersion(0, 2, 0);
+
+    ReactNativeVersionCheck.checkVersions();
+    expect(mockConsoleError).toHaveBeenCalledTimes(1);
+    expect(mockConsoleError.mock.calls[0][0]).toContain(
+      'React Native version mismatch',
+    );
+  });
+
+  it("logs error when the major doesn't match", () => {
+    _mockJsVersion(1, 0, 0);
+    _mockNativeVersion(2, 0, 0);
+
+    ReactNativeVersionCheck.checkVersions();
+    expect(mockConsoleError).toHaveBeenCalledTimes(1);
+    expect(mockConsoleError.mock.calls[0][0]).toContain(
+      'React Native version mismatch',
+    );
+  });
+
+  it("doesn't log error if the patch doesn't match", () => {
+    _mockJsVersion(0, 1, 0);
+    _mockNativeVersion(0, 1, 2);
+
+    ReactNativeVersionCheck.checkVersions();
+    expect(mockConsoleError).toHaveBeenCalledTimes(0);
+  });
+
+  it("doesn't log error if the prerelease doesn't match", () => {
+    _mockJsVersion(0, 1, 0, 'beta.0');
+    _mockNativeVersion(0, 1, 0, 'alpha.1');
+
+    ReactNativeVersionCheck.checkVersions();
+    expect(mockConsoleError).toHaveBeenCalledTimes(0);
+  });
+});
+
+function _mockJsVersion(
+  major: number = 0,
+  minor: number = 0,
+  patch: number = 0,
+  prerelease: string | null = null,
+) {
+  ReactNativeVersion.version.major = major;
+  ReactNativeVersion.version.minor = minor;
+  ReactNativeVersion.version.patch = patch;
+  ReactNativeVersion.version.prerelease = prerelease;
+}
+
+function _mockNativeVersion(
+  major: number = 0,
+  minor: number = 0,
+  patch: number = 0,
+  prerelease: string | null = null,
+) {
+  // $FlowFixMe[incompatible-type]
+  // $FlowFixMe[prop-missing]
+  Platform.__constants = {
+    ...Platform.constants,
+    reactNativeVersion: {major, minor, patch, prerelease},
+  };
+}

packages/react-native/Libraries/Core/__tests__/ReactNativeVersionCheck-test.js

@@ -8,7 +8,7 @@
  * @format
  */
 
-'use strict';
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
 import type {AttributeConfiguration} from '../../../Renderer/shims/ReactNativeTypes';