Add spawnSync wrapper

Author: Yosif Yosifov

lib/child-process.ts

@@ -12,6 +12,18 @@ export function execSync(command: string, opts?: any): any {
 	}
 }
 
+export function spawnSync(command: string, args: string[], opts?: any): any {
+	try {
+		return child_process.spawnSync(command, args, opts);
+	} catch (err) {
+		if (opts && opts.skipError) {
+			return err;
+		} else {
+			throw (new Error(`Error ${err.message} while executing ${command}.`));
+		}
+	}
+}
+
 export function spawn(command: string, args: string[], opts?: any): Promise<string> {
 	return new Promise<string>((resolve, reject) => {
 		let capturedOut = "";

lib/simctl.ts

@@ -1,5 +1,4 @@
 import childProcess = require("./child-process");
-import nodeChildProcess = require("child_process");
 import errors = require("./errors");
 import options = require("./options");
 import * as _ from "lodash";
@@ -118,6 +117,10 @@ export class Simctl implements ISimctl {
 	}
 
 	private simctlExec(command: string, args: string[], opts?: any): any {
-		return nodeChildProcess.spawnSync("xcrun", ["simctl", command].concat(args), opts).stdout.toString().trim();
+		let result = childProcess.spawnSync("xcrun", ["simctl", command].concat(args), opts);
+		if(result && result.stdout) {
+			return result.stdout.toString().trim();
+		}
+		return '';
 	}
 }