Revert "Prevent 'yarnpkg not found' error from displaying to users."

This reverts commit a52eac9.

Reset last commit

Author: abhisheksoni27

create-react-native-app/package.json

@@ -1,6 +1,6 @@
 {
   "name": "create-react-native-app",
-  "version": "0.0.6",
+  "version": "0.0.5",
   "description": "Create React Native apps with no build configuration.",
   "license": "BSD-3-Clause",
   "keywords": ["react-native", "react"],

create-react-native-app/src/index.js

@@ -40,19 +40,6 @@ if (commands.length === 0) {
 
 createApp(commands[0], !!argv.verbose, argv['scripts-version']).then(() => {});
 
-// use yarn if it's available, otherwise use npm
-function shouldUseYarn() {
-  try {
-    const result = spawn.sync('yarnpkg', ['--version'], { stdio: 'ignore' });
-    if (result.error || result.status !== 0) {
-      return false;
-    }
-    return true;
-  } catch (e) {
-    return false;
-  }
-}
-
 async function createApp(name: string, verbose: boolean, version: ?string): Promise<void> {
   const root = path.resolve(name);
   const appName = path.basename(root);
@@ -91,37 +78,45 @@ function install(
   verbose: boolean,
   callback: (code: number, command: string, args: Array<string>) => Promise<void>
 ): void {
-  const useYarn = shouldUseYarn();
-  let args, cmd, result;
-
-  if (useYarn) {
-    cmd = 'yarnpkg';
-    args = ['add'];
+  let args = ['add', '--dev', '--exact', '--ignore-optional', packageToInstall];
+  const proc = spawn('yarnpkg', args, { stdio: 'inherit' });
 
-    if (verbose) {
-      args.push('--verbose');
+  let yarnExists = true;
+  proc.on('error', function(err) {
+    if (err.code === 'ENOENT') {
+      yarnExists = false;
     }
+  });
 
-    args = args.concat(['--dev', '--exact', '--ignore-optional', packageToInstall]);
-    result = spawn.sync(cmd, args, { stdio: 'inherit' });
-  } else {
+  proc.on('close', function(code) {
+    if (yarnExists) {
+      callback(code, 'yarnpkg', args).then(
+        () => {},
+        e => {
+          throw e;
+        }
+      );
+      return;
+    }
+    // No Yarn installed, continuing with npm.
     args = ['install'];
 
     if (verbose) {
       args.push('--verbose');
     }
-    cmd = 'npm';
-    args = args.concat(['--save-dev', '--save-exact', packageToInstall]);
 
-    result = spawn.sync(cmd, args, { stdio: 'inherit' });
-  }
+    args = args.concat(['--save-dev', '--save-exact', packageToInstall]);
 
-  callback(result.status, cmd, args).then(
-    () => {},
-    e => {
-      throw e;
-    }
-  );
+    const npmProc = spawn('npm', args, { stdio: 'inherit' });
+    npmProc.on('close', function(code) {
+      callback(code, 'npm', args).then(
+        () => {},
+        e => {
+          throw e;
+        }
+      );
+    });
+  });
 }
 
 async function run(