Dynamically load packages for dartdevc tests in test.dart.

pkg/dev_compiler/tool/build_pkgs.dart

 #!/usr/bin/env dart
 import 'dart:io';
 
+import 'package:path/path.dart' as p;
+
 import 'package:dev_compiler/src/compiler/command.dart';
 
-/// Compiles the packages that the DDC tests use to JS into:
+final String scriptDirectory = p.dirname(p.fromUri(Platform.script));
+String outputDirectory;
+
+/// Compiles the packages that the DDC tests use to JS into the given output
+/// directory. Usage:
 ///
-/// gen/codegen_output/pkg/...
+///     dart build_pkgs.dart <output_dir> [travis]
 ///
-/// Assumes the working directory is pkg/dev_compiler.
-///
-/// If no arguments are passed, builds the all of the modules tested on Travis.
-/// If "test" is passed, only builds the modules needed by the tests.
+/// If "travis" is passed, builds the all of the modules tested on Travis.
+/// Otherwise, only builds the modules needed by the tests.
 void main(List<String> arguments) {
-  var test = arguments.length == 1 && arguments[0] == 'test';
+  var isTravis = arguments.isNotEmpty && arguments.last == "travis";
+  if (isTravis) arguments.removeLast();
 
-  new Directory("gen/codegen_output/pkg").createSync(recursive: true);
+  if (arguments.length != 1) {
+    print("Usage: dart build_pkgs.dart <output_dir> [travis]");
+    exit(1);
+  }
+
+  outputDirectory = arguments[0];
+  new Directory(outputDirectory).createSync(recursive: true);
 
   // Build leaf packages. These have no other package dependencies.
 
   // Under pkg.
   compileModule('async_helper');
   compileModule('expect', libs: ['minitest']);
   compileModule('js', libs: ['js_util']);
   compileModule('meta');
-  if (!test) {
+  if (isTravis) {
     compileModule('lookup_map');
     compileModule('microlytics', libs: ['html_channels']);
     compileModule('typed_mock');
   }
 
   // Under third_party/pkg.
   compileModule('collection');
   compileModule('matcher');
   compileModule('path');
-  if (!test) {
+  if (isTravis) {
     compileModule('args', libs: ['command_runner']);
     compileModule('charcode');
     compileModule('fixnum');
     compileModule('logging');
     compileModule('markdown');
     compileModule('mime');
     compileModule('plugin', libs: ['manager']);
     compileModule('typed_data');
     compileModule('usage');
     compileModule('utf');
     compileModule('when');
   }
 
   // Composite packages with dependencies.
   compileModule('stack_trace', deps: ['path']);
-  if (!test) {
+  if (isTravis) {
     compileModule('async', deps: ['collection']);
   }
 
-  if (test) {
+  if (!isTravis) {
     compileModule('unittest',
         deps: ['matcher', 'path', 'stack_trace'],
         libs: ['html_config', 'html_individual_config', 'html_enhanced_config'],
         unsafeForceCompile: true);
   }
 }
 
 /// Compiles a [module] with a single matching ".dart" library and additional
 /// [libs] and [deps] on other modules.
 void compileModule(String module,
     {List<String> libs, List<String> deps, bool unsafeForceCompile: false}) {
+  var sdkSummary = p.join(scriptDirectory, "../lib/sdk/ddc_sdk.sum");
   var args = [
-    '--dart-sdk-summary=lib/sdk/ddc_sdk.sum',
-    '-ogen/codegen_output/pkg/$module.js'
+    '--dart-sdk-summary=$sdkSummary',
+    '-o${outputDirectory}/$module.js'
   ];
 
   // There is always a library that matches the module.
   args.add('package:$module/$module.dart');
 
   // Add any additional libraries.
   if (libs != null) {
     for (var lib in libs) {
       args.add('package:$module/$lib.dart');
     }
   }
 
   // Add summaries for any modules this depends on.
   if (deps != null) {
     for (var dep in deps) {
-      args.add('-sgen/codegen_output/pkg/$dep.sum');
+      args.add('-s${outputDirectory}/$dep.sum');
     }
   }
 
   if (unsafeForceCompile) {
     args.add('--unsafe-force-compile');
   }
 
   // TODO(rnystrom): Hack. DDC has its own forked copy of async_helper that
   // has a couple of differences from pkg/async_helper. We should unfork them,
   // but I'm not sure how they'll affect the other non-DDC tests. For now, just
   // use ours.
   if (module == 'async_helper') {
-    args.add('--url-mapping=package:async_helper/async_helper.dart,'
-        'test/codegen/async_helper.dart');
+    args.add('--url-mapping=package:async_helper/async_helper.dart,' +
+        p.join(scriptDirectory, "../test/codegen/async_helper.dart"));
   }
 
-  compile(args);
+  var exitCode = compile(args);
+  if (exitCode != 0) exit(exitCode);
 }