Compile and run Hello World!

tests/compiler/dart2js/kernel/compiler_helper.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.compiler_helper;
 
 import 'dart:async';
 import 'dart:io';
@@ skipping 121 matching lines @@
   MemoryDillLibraryLoaderTask(KernelToElementMapImpl elementMap,
       DiagnosticReporter reporter, Measurer measurer, this.program)
       : super(elementMap, null, null, reporter, measurer);
 
   Future<LoadedLibraries> loadLibrary(Uri resolvedUri,
       {bool skipFileWithPartOfTag: false}) async {
     return createLoadedLibraries(program);
   }
 }
 
-Future<Compiler> compileWithDill(
-    Uri entryPoint, Map<String, String> memorySourceFiles, List<String> options,
-    {bool printSteps: false,
-    CompilerOutput compilerOutput,
-    void beforeRun(Compiler compiler)}) async {
+Future createTemp(Uri entryPoint, Map<String, String> memorySourceFiles,
+    {bool printSteps: false}) async {
   if (memorySourceFiles.isNotEmpty) {
     Directory dir = await Directory.systemTemp.createTemp('dart2js-with-dill');
     if (printSteps) {
       print('--- create temp directory $dir -------------------------------');
     }
     memorySourceFiles.forEach((String name, String source) {
       new File.fromUri(dir.uri.resolve(name)).writeAsStringSync(source);
     });
     entryPoint = dir.uri.resolve(entryPoint.path);
   }
   if (printSteps) {
     print('---- generate dill -----------------------------------------------');
   }
 
   Uri dillFile = Uri.parse('$entryPoint.dill');
   String buildDir = Platform.isMacOS ? 'xcodebuild' : 'out';
   String configuration =
       Platform.environment['DART_CONFIGURATION'] ?? 'ReleaseX64';
   await generate.main([
     '--platform=$buildDir/$configuration/patched_dart2js_sdk/platform.dill',
     '$entryPoint'
   ]);
+  return dillFile;
+}
+
+Future<Compiler> compileWithDill(
+    Uri entryPoint, Map<String, String> memorySourceFiles, List<String> options,
+    {bool printSteps: false,
+    CompilerOutput compilerOutput,
+    void beforeRun(Compiler compiler)}) async {
+  Uri dillFile =
+      await createTemp(entryPoint, memorySourceFiles, printSteps: printSteps);
 
   if (printSteps) {
     print('---- compile from dill $dillFile ---------------------------------');
   }
   Compiler compiler = compilerFor(
       entryPoint: dillFile,
       options: [Flags.loadFromDill]..addAll(options),
       outputProvider: compilerOutput);
   ElementResolutionWorldBuilder.useInstantiationMap = true;
   compiler.resolution.retainCachesForTesting = true;
   if (beforeRun != null) {
     beforeRun(compiler);
   }
   await compiler.run(dillFile);
   return compiler;
 }