Create React Native example project

Summary:
This diff creates a sample React Native project (based on the 0.62-rc.0 template).

This example is created like:
(Documenting this here as in the future this might be easier than upgrading the project itself)

1. Run `npx react-native init ReactNativeFlipperExample --version 0.62.0-rc.0`
2. Follow the installation steps to enable Flipper, that is, call `initializeFlipper(this, getReactNativeHost().getReactInstanceManager());` at the end of the `onCreate` method in `MainApplication.java`
3. Put `FlipperTicTacToe` in the root of the project, and call it from `App.js` as a component
4. install `react-native-flipper` as dependency
5. install `relative-deps` as dev dependency, and set it up as shown in `package.json`. This tool make sure that we build and test this project against the version of react-native-flipper in this repository, rather than against the one on NPM.
6. removed some stuff, like tests and linting, which is just in the way in this repo

This PR does not support iOS, as Flipper + RN iOS is still broken in 0.62.0-rc.0, and the current version of react-native-flipper doesn't support iOS yet either.

Documentation on how to set up Flipper in general is not part of this Diff

_N.B. since this is a **public** project, to be visible and runnable by our OSS community, the build setup is kept plain, vanilla, react-native, and **not** wired up to our normal / internal build processes. This is also the reason that lint suggestions beyond the license headers have been ignored. If any others should be applied, it is probably the official react native template that requires updating_

Reviewed By: passy

Differential Revision: D19449295

fbshipit-source-id: 2aeb6044f8dd01f09a95350c84fff2419d685a65

react-native/ReactNativeFlipperExample/ios/ReactNativeFlipperExampleTests/Info.plist

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>BNDL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+</dict>
+</plist>

react-native/ReactNativeFlipperExample/ios/ReactNativeFlipperExampleTests/ReactNativeFlipperExampleTests.m

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <UIKit/UIKit.h>
+#import <XCTest/XCTest.h>
+
+#import <React/RCTLog.h>
+#import <React/RCTRootView.h>
+
+#define TIMEOUT_SECONDS 600
+#define TEXT_TO_LOOK_FOR @"Welcome to React"
+
+@interface ReactNativeFlipperExampleTests : XCTestCase
+
+@end
+
+@implementation ReactNativeFlipperExampleTests
+
+- (BOOL)findSubviewInView:(UIView *)view matching:(BOOL(^)(UIView *view))test
+{
+  if (test(view)) {
+    return YES;
+  }
+  for (UIView *subview in [view subviews]) {
+    if ([self findSubviewInView:subview matching:test]) {
+      return YES;
+    }
+  }
+  return NO;
+}
+
+- (void)testRendersWelcomeScreen
+{
+  UIViewController *vc = [[[RCTSharedApplication() delegate] window] rootViewController];
+  NSDate *date = [NSDate dateWithTimeIntervalSinceNow:TIMEOUT_SECONDS];
+  BOOL foundElement = NO;
+
+  __block NSString *redboxError = nil;
+#ifdef DEBUG
+  RCTSetLogFunction(^(RCTLogLevel level, RCTLogSource source, NSString *fileName, NSNumber *lineNumber, NSString *message) {
+    if (level >= RCTLogLevelError) {
+      redboxError = message;
+    }
+  });
+#endif
+
+  while ([date timeIntervalSinceNow] > 0 && !foundElement && !redboxError) {
+    [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.1]];
+    [[NSRunLoop mainRunLoop] runMode:NSRunLoopCommonModes beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.1]];
+
+    foundElement = [self findSubviewInView:vc.view matching:^BOOL(UIView *view) {
+      if ([view.accessibilityLabel isEqualToString:TEXT_TO_LOOK_FOR]) {
+        return YES;
+      }
+      return NO;
+    }];
+  }
+
+#ifdef DEBUG
+  RCTSetLogFunction(RCTDefaultLogFunction);
+#endif
+
+  XCTAssertNil(redboxError, @"RedBox error: %@", redboxError);
+  XCTAssertTrue(foundElement, @"Couldn't find element with text '%@' in %d seconds", TEXT_TO_LOOK_FOR, TIMEOUT_SECONDS);
+}
+
+
+@end