Don't access sys.newLine inside unit tests

src/compiler/commandLineParser.ts

@@ -895,7 +895,7 @@ namespace ts {
      * @param fileNames array of filenames to be generated into tsconfig.json
      */
     /* @internal */
-    export function generateTSConfig(options: CompilerOptions, fileNames: string[]): string {
+    export function generateTSConfig(options: CompilerOptions, fileNames: string[], newLine: string): string {
         const compilerOptions = extend(options, defaultInitCompilerOptions);
         const configurations: { compilerOptions: MapLike<CompilerOptionsValue>; files?: string[] } = {
             compilerOptions: serializeCompilerOptions(compilerOptions)
@@ -1053,7 +1053,7 @@ namespace ts {
             }
             result.push(`}`);
 
-            return result.join(sys.newLine);
+            return result.join(newLine);
         }
     }