Add solution of entry point not exist error for Expo on macOS to Know…

…n issues for master branch (microsoft#1338)

* Add solution of entry point not exist error for Expo on macOS to Known issues (microsoft#1337)

* add lines to content of metro.config.json in smoke tests and add description of error to known issues in readme

* Update README.md

Co-authored-by: Yuri Skorokhodov <v-yuskor@microsoft.com>

* Update test/smoke/package/src/helpers/setupEnvironmentHelper.ts

Co-authored-by: Yuri Skorokhodov <v-yuskor@microsoft.com>

* Update test/smoke/package/src/helpers/setupEnvironmentHelper.ts

Co-authored-by: Yuri Skorokhodov <v-yuskor@microsoft.com>

Co-authored-by: Yuri Skorokhodov <v-yuskor@microsoft.com>

* Apply suggestions from code review

Co-authored-by: RedMickey <33267199+RedMickey@users.noreply.github.com>

Co-authored-by: Yuri Skorokhodov <v-yuskor@microsoft.com>
Co-authored-by: RedMickey <33267199+RedMickey@users.noreply.github.com>

README.md

@@ -503,7 +503,8 @@ Debugger doesn't stop at breakpoints | Breakpoints require sourcemaps to be corr
 'adb: command not found'             | If you receive an error `adb: command not found`, you need to update your system Path to include the location of your *ADB* executable.The *ADB* executable file is located in a subdirectory along with your other Android SDK files.
 Targeting iPhone 6 doesn't work      | There was a known issue with React Native ([#5850](https://github.com/facebook/react-native/issues/5850)) but it was fixed. Please upgrade your version of React Native.
 Can't communicate with socket pipe    | (Linux only) If you have two workspaces open that only differ in casing, the extension will fail to communicate effectively.
-"Add configuration" button doesn't work when trying to add debug configuration to `launch.json` | You may need to have to add in some json to `launch.json` manually. Please, see ([#985](https://github.com/Microsoft/vscode-react-native/issues/985))
+"Add configuration" button doesn't work when trying to add debug configuration to `launch.json` | You have to add some json configuration to `launch.json` manually. Please, see ([#985](https://github.com/Microsoft/vscode-react-native/issues/985)).
+Error `None of these files exist: * .vscode/exponentIndex` appears when running React Native apps via Expo | On some project configurations (mostly on macOS) there could be problems with running RN app via Expo for the first time. You can resolve this by explicitly adding `module.exports.watchFolders = ['.vscode'];` to your Metro config. This will help Metro bundler to find the custom entry point generated by the extension needed to work with Expo. For details you can see the issue ([#1327](https://github.com/microsoft/vscode-react-native/issues/1327)).
 
 [Known-Issues](https://github.com/Microsoft/vscode-react-native/issues?q=is%3Aissue+label%3Aknown-issues) provides a complete list of active and resolved issues.
 

test/smoke/package/src/helpers/setupEnvironmentHelper.ts

@@ -252,7 +252,11 @@ module.exports.cacheStores = [
 ];
 
 // Redirect Haste Map cache
-module.exports.hasteMapCacheDirectory = ".cache";`;
+module.exports.hasteMapCacheDirectory = ".cache";
+
+// Due to the fact that Metro bundler on MacOS has problems with scanning files and folders starting with a dot (hidden folders), for example './vscode',
+// the first time when the packager starts, it cannot find the './vscode/exponentIndex.js' file. So we add this folder to scanning manually.
+module.exports.watchFolders = ['.vscode'];`;
         fs.appendFileSync(metroConfigPath, patchContent);
         const contentAfterPatching = fs.readFileSync(metroConfigPath);
         console.log(`*** Content of a metro.config.js after patching: ${contentAfterPatching}`);