Move JS-native version check to its own module + unit tests + prefix Obj-C macro w/RCT

- The version check that ensures the JS and native versions match is now in its own module for two reasons: it is easier to test and it allows react-native-windows to override just this module to implement its own version check (ex: more advanced checks for RNW-specific code).
- Added unit tests for the version checking to specify its behavior more clearly, including parity between dev and prod to avoid prod-only behavior and mitigate SEVs.
- Prefixed the Obj-C `#define` with `RCT_` to conform with other RN globals.

Test Plan: Ran `yarn jest` to run all tests. Compiled iOS app and launched it, which runs the version check.

Author: ide

Libraries/Core/InitializeCore.js

@@ -116,25 +116,9 @@ if (!global.__fbDisableExceptionsManager) {
   ErrorUtils.setGlobalHandler(handleError);
 }
 
-const {PlatformConstants} = require('NativeModules');
-if (PlatformConstants) {
-  const formatVersion = version =>
-    `${version.major}.${version.minor}.${version.patch}` +
-    (version.prerelease !== null ? `-${version.prerelease}` : '');
-
-  const ReactNativeVersion = require('ReactNativeVersion');
-  const nativeVersion = PlatformConstants.reactNativeVersion;
-  if (ReactNativeVersion.version.major !== nativeVersion.major ||
-      ReactNativeVersion.version.minor !== nativeVersion.minor) {
-    throw new Error(
-      `React Native version mismatch.\n\nJavaScript version: ${formatVersion(ReactNativeVersion.version)}\n` +
-      `Native version: ${formatVersion(nativeVersion)}\n\n` +
-      'Make sure that you have rebuilt the native code. If the problem persists ' +
-      'try clearing the watchman and packager caches with `watchman watch-del-all ' +
-      '&& react-native start --reset-cache`.'
-    );
-  }
-}
+// Check for compatibility between the JS and native code
+const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+ReactNativeVersionCheck.checkVersions();
 
 // Set up collections
 const _shouldPolyfillCollection = require('_shouldPolyfillES6Collection');

Libraries/Core/ReactNativeVersionCheck.js

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule ReactNativeVersionCheck
+ * @flow
+ */
+'use strict';
+
+const {PlatformConstants} = require('NativeModules');
+const ReactNativeVersion = require('ReactNativeVersion');
+
+/**
+ * Checks that the version of this React Native JS is compatible with the native
+ * code, throwing an error if it isn't.
+ *
+ * The existence of this module is part of the public interface of React Native
+ * even though it is used only internally within React Native. React Native
+ * implementations for other platforms (ex: Windows) may override this module
+ * and rely on its existence as a separate module.
+ */
+exports.checkVersions = function checkVersions(): void {
+  if (!PlatformConstants) {
+    return;
+  }
+
+  const nativeVersion = PlatformConstants.reactNativeVersion;
+  if (
+    ReactNativeVersion.version.major !== nativeVersion.major ||
+    ReactNativeVersion.version.minor !== nativeVersion.minor
+  ) {
+    throw new Error(
+      `React Native version mismatch.\n\nJavaScript version: ${_formatVersion(
+        ReactNativeVersion.version
+      )}\n` +
+        `Native version: ${_formatVersion(nativeVersion)}\n\n` +
+        'Make sure that you have rebuilt the native code. If the problem ' +
+        'persists try clearing the Watchman and packager caches with ' +
+        '`watchman watch-del-all && react-native start --reset-cache`.'
+    );
+  }
+};
+
+function _formatVersion(version): string {
+  return (
+    `${version.major}.${version.minor}.${version.patch}` +
+    (version.prerelease !== null ? `-${version.prerelease}` : '')
+  );
+}

Libraries/Core/__tests__/ReactNativeVersionCheck-test.js

@@ -0,0 +1,105 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+describe('checkVersion', () => {
+  describe('in development', () => {
+    _setDevelopmentModeForTests(true);
+    _defineCheckVersionTests();
+  });
+
+  describe('in production', () => {
+    _setDevelopmentModeForTests(false);
+    _defineCheckVersionTests();
+  });
+});
+
+function _setDevelopmentModeForTests(dev) {
+  let originalDev;
+
+  beforeAll(() => {
+    originalDev = global.__DEV__;
+    global.__DEV__ = dev;
+  });
+
+  afterAll(() => {
+    global.__DEV__ = originalDev;
+  });
+}
+
+function _defineCheckVersionTests() {
+  afterEach(() => {
+    jest.resetModules();
+  });
+
+  it('passes when all the versions are zero', () => {
+    jest.dontMock('ReactNativeVersion');
+    _mockNativeVersion(0, 0, 0);
+
+    const ReactNativeVersion = require('ReactNativeVersion');
+    const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+    expect(ReactNativeVersion).toMatchObject({
+      version: {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);
+
+    const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+  });
+
+  it("throws when the minor doesn't match when the major is zero", () => {
+    _mockJsVersion(0, 1, 0);
+    _mockNativeVersion(0, 2, 0);
+
+    const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+    expect(() => ReactNativeVersionCheck.checkVersions()).toThrowError(
+      /React Native version mismatch/
+    );
+  });
+
+  it("doesn't throw if the patch doesn't match", () => {
+    _mockJsVersion(0, 1, 0);
+    _mockNativeVersion(0, 1, 2);
+
+    const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+  });
+
+  it("doesn't throw if the prerelease doesn't match", () => {
+    _mockJsVersion(0, 1, 0, 'beta.0');
+    _mockNativeVersion(0, 1, 0, 'alpha.1');
+
+    const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
+    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+  });
+}
+
+function _mockJsVersion(major = 0, minor = 0, patch = 0, prerelease = null) {
+  jest.doMock('ReactNativeVersion', () => ({
+    version: {major, minor, patch, prerelease},
+  }));
+}
+
+function _mockNativeVersion(
+  major = 0,
+  minor = 0,
+  patch = 0,
+  prerelease = null
+) {
+  jest.doMock('NativeModules', () => ({
+    PlatformConstants: {
+      reactNativeVersion: {major, minor, patch, prerelease},
+    },
+  }));
+}

React/Base/RCTPlatform.m

@@ -47,7 +47,7 @@ + (BOOL)requiresMainQueueSetup
     @"systemName": [device systemName],
     @"interfaceIdiom": interfaceIdiom([device userInterfaceIdiom]),
     @"isTesting": @(RCTRunningInTestEnvironment()),
-    @"reactNativeVersion": REACT_NATIVE_VERSION,
+    @"reactNativeVersion": RCT_REACT_NATIVE_VERSION,
   };
 }
 

React/Base/RCTVersion.h

@@ -9,7 +9,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-#define REACT_NATIVE_VERSION @{ \
+#define RCT_REACT_NATIVE_VERSION @{ \
   @"major": @(0), \
   @"minor": @(0), \
   @"patch": @(0), \

scripts/versiontemplates/RCTVersion.h.template

@@ -9,7 +9,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-#define REACT_NATIVE_VERSION @{ \
+#define RCT_REACT_NATIVE_VERSION @{ \
   @"major": ${major}, \
   @"minor": ${minor}, \
   @"patch": ${patch}, \