Remove ReactNativeVersionCheck __DEV__ gating, print error instead of throwing

Reviewed By: cblappert

Differential Revision: D6192020

fbshipit-source-id: 026f376d6d43ab3de188f94f2a4d5f0cf485733c

Libraries/Core/InitializeCore.js

@@ -126,10 +126,8 @@ if (!global.__fbDisableExceptionsManager) {
 }
 
 // Check for compatibility between the JS and native code
-if (__DEV__) {
 const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
 ReactNativeVersionCheck.checkVersions();
-}
 
 // Set up Promise
 // The native Promise implementation throws the following error:

Libraries/Core/ReactNativeVersionCheck.js

@@ -34,7 +34,7 @@ exports.checkVersions = function checkVersions(): void {
     ReactNativeVersion.version.major !== nativeVersion.major ||
     ReactNativeVersion.version.minor !== nativeVersion.minor
   ) {
-    throw new Error(
+    console.error(
       `React Native version mismatch.\n\nJavaScript version: ${_formatVersion(
         ReactNativeVersion.version,
       )}\n` +

Libraries/Core/__tests__/ReactNativeVersionCheck-test.js

@@ -36,8 +36,24 @@ function _setDevelopmentModeForTests(dev) {
 }
 
 function _defineCheckVersionTests() {
+  const consoleError = console.error;
+  const globalConsole = global.console;
+
+  let spyOnConsoleError;
+  let consoleOutput;
+
+  beforeEach(() => {
+    consoleOutput = '';
+    console.error = jest.fn();
+    global.console = {error: jest.fn(error => (consoleOutput += error))};
+    spyOnConsoleError = jest.spyOn(global.console, 'error');
+  });
+
   afterEach(() => {
     jest.resetModules();
+    console.error = consoleError;
+    global.console = globalConsole;
+    spyOnConsoleError.mockReset();
   });
 
   it('passes when all the versions are zero', () => {
@@ -60,40 +76,43 @@ function _defineCheckVersionTests() {
     expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
   });
 
-  it("throws when the minor doesn't match when the major is zero", () => {
+  it("logs error 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/,
-    );
+
+    ReactNativeVersionCheck.checkVersions();
+    expect(spyOnConsoleError).toHaveBeenCalledTimes(1);
+    expect(consoleOutput).toMatch(/React Native version mismatch/);
   });
 
-  it("throws when the major doesn't match", () => {
+  it("logs error when the major doesn't match", () => {
     _mockJsVersion(1, 0, 0);
     _mockNativeVersion(2, 0, 0);
 
     const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
-    expect(() => ReactNativeVersionCheck.checkVersions()).toThrowError(
-      /React Native version mismatch/,
-    );
+    ReactNativeVersionCheck.checkVersions();
+    expect(spyOnConsoleError).toHaveBeenCalledTimes(1);
+    expect(consoleOutput).toMatch(/React Native version mismatch/);
   });
 
-  it("doesn't throw if the patch doesn't match", () => {
+  it("doesn't log error if the patch doesn't match", () => {
     _mockJsVersion(0, 1, 0);
     _mockNativeVersion(0, 1, 2);
 
     const ReactNativeVersionCheck = require('ReactNativeVersionCheck');
-    expect(() => ReactNativeVersionCheck.checkVersions()).not.toThrow();
+    ReactNativeVersionCheck.checkVersions();
+    expect(spyOnConsoleError).toHaveBeenCalledTimes(0);
   });
 
-  it("doesn't throw if the prerelease doesn't match", () => {
+  it("doesn't log error 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();
+    ReactNativeVersionCheck.checkVersions();
+    expect(spyOnConsoleError).toHaveBeenCalledTimes(0);
   });
 }