Check whether packager is running in RCTBundleURLProvider for saved JSLocation

Summary:
Changelog:
Adding packager running check when RCTBundleURLProvider is returning JSLocation, this prevents an invalid address from being returned which might cause various issues.

Reviewed By: cpojer

Differential Revision: D22390156

fbshipit-source-id: a20dbf63103158a34cbf6dc0ae8349b2f9e5b0a8

Author: jimmy623

RNTester/RNTesterUnitTests/RCTBundleURLProviderTests.m

@@ -10,6 +10,8 @@
 #import <React/RCTBundleURLProvider.h>
 #import <React/RCTUtils.h>
 
+#import "OCMock/OCMock.h"
+
 static NSString *const testFile = @"test.jsbundle";
 static NSString *const mainBundle = @"main.jsbundle";
 
@@ -94,6 +96,8 @@ - (void)testLocalhostURL
 
 - (void)testIPURL
 {
+  id classMock = OCMClassMock([RCTBundleURLProvider class]);
+  [[[classMock stub] andReturnValue:@YES] isPackagerRunning:[OCMArg any]];
   RCTBundleURLProvider *settings = [RCTBundleURLProvider sharedSettings];
   settings.jsLocation = @"192.168.1.1";
   NSURL *URL = [settings jsBundleURLForBundleRoot:testFile fallbackResource:nil];

React/Base/RCTBundleURLProvider.mm

@@ -125,6 +125,11 @@ + (BOOL)isPackagerRunning:(NSString *)host
 - (NSString *)packagerServerHost
 {
   NSString *location = [self jsLocation];
+#if RCT_DEV_MENU
+  if (![RCTBundleURLProvider isPackagerRunning:location]) {
+    location = nil;
+  }
+#endif
   if (location != nil) {
     return location;
   }