Use the package_resolver package.

lib/src/runner/configuration.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:io';
 
 import 'package:boolean_selector/boolean_selector.dart';
 import 'package:collection/collection.dart';
 import 'package:glob/glob.dart';
 import 'package:path/path.dart' as p;
@@ skipping 50 matching lines @@
   /// The selector indicating which platforms the tests support.
   ///
   /// When [merge]d, this is intersected with the other configuration's
   /// supported platforms.
   final PlatformSelector testOn;
 
   /// Whether to pause for debugging after loading each test suite.
   bool get pauseAfterLoad => _pauseAfterLoad ?? false;
   final bool _pauseAfterLoad;
 
-  /// The package root for resolving "package:" URLs.
-  String get packageRoot => _packageRoot ?? p.join(p.current, 'packages');
-  final String _packageRoot;
-
   /// The path to dart2js.
   String get dart2jsPath => _dart2jsPath ?? p.join(sdkDir, 'bin', 'dart2js');
   final String _dart2jsPath;
 
   /// Additional arguments to pass to dart2js.
   final List<String> dart2jsArgs;
 
   /// The path to a mirror of this package containing precompiled JS.
   ///
   /// This is used by the internal Google test runner so that test compilation
@@ skipping 191 matching lines @@
       bool help,
       bool version,
       bool verboseTrace,
       bool jsTrace,
       bool skip,
       String skipReason,
       bool runSkipped,
       PlatformSelector testOn,
       bool pauseAfterLoad,
       bool color,
-      String packageRoot,
       String dart2jsPath,
       Iterable<String> dart2jsArgs,
       String precompiledPath,
       String reporter,
       int pubServePort,
       int concurrency,
       int shardIndex,
       int totalShards,
       Timeout timeout,
       Iterable<Pattern> patterns,
@@ skipping 11 matching lines @@
         help: help,
         version: version,
         verboseTrace: verboseTrace,
         jsTrace: jsTrace,
         skip: skip,
         skipReason: skipReason,
         runSkipped: runSkipped,
         testOn: testOn,
         pauseAfterLoad: pauseAfterLoad,
         color: color,
-        packageRoot: packageRoot,
         dart2jsPath: dart2jsPath,
         dart2jsArgs: dart2jsArgs,
         precompiledPath: precompiledPath,
         reporter: reporter,
         pubServePort: pubServePort,
         concurrency: concurrency,
         shardIndex: shardIndex,
         totalShards: totalShards,
         timeout: timeout,
         patterns: patterns,
@@ skipping 50 matching lines @@
           bool help,
           bool version,
           bool verboseTrace,
           bool jsTrace,
           bool skip,
           this.skipReason,
           bool runSkipped,
           PlatformSelector testOn,
           bool pauseAfterLoad,
           bool color,
-          String packageRoot,
           String dart2jsPath,
           Iterable<String> dart2jsArgs,
           this.precompiledPath,
           String reporter,
           int pubServePort,
           int concurrency,
           this.shardIndex,
           this.totalShards,
           Timeout timeout,
           Iterable<Pattern> patterns,
           Iterable<TestPlatform> platforms,
           Iterable<String> paths,
           Glob filename,
           Iterable<String> chosenPresets,
           BooleanSelector includeTags,
           BooleanSelector excludeTags,
           Iterable<String> addTags,
           Map<BooleanSelector, Configuration> tags,
           Map<PlatformSelector, Configuration> onPlatform,
           Map<String, Configuration> presets})
       : _help = help,
         _version = version,
         _verboseTrace = verboseTrace,
         _jsTrace = jsTrace,
         _skip = skip,
         _runSkipped = runSkipped,
         testOn = testOn ?? PlatformSelector.all,
         _pauseAfterLoad = pauseAfterLoad,
         _color = color,
-        _packageRoot = packageRoot,
         _dart2jsPath = dart2jsPath,
         dart2jsArgs = dart2jsArgs?.toList() ?? [],
         _reporter = reporter,
         pubServeUrl = pubServePort == null
             ? null
             : Uri.parse("http://localhost:$pubServePort"),
         _concurrency = concurrency,
         timeout = (pauseAfterLoad ?? false)
             ? Timeout.none
             : (timeout == null ? new Timeout.factor(1) : timeout),
@@ skipping 54 matching lines @@
         help: other._help ?? _help,
         version: other._version ?? _version,
         verboseTrace: other._verboseTrace ?? _verboseTrace,
         jsTrace: other._jsTrace ?? _jsTrace,
         skip: other._skip ?? _skip,
         skipReason: other.skipReason ?? skipReason,
         runSkipped: other._runSkipped ?? _runSkipped,
         testOn: testOn.intersection(other.testOn),
         pauseAfterLoad: other._pauseAfterLoad ?? _pauseAfterLoad,
         color: other._color ?? _color,
-        packageRoot: other._packageRoot ?? _packageRoot,
         dart2jsPath: other._dart2jsPath ?? _dart2jsPath,
         dart2jsArgs: dart2jsArgs.toList()..addAll(other.dart2jsArgs),
         precompiledPath: other.precompiledPath ?? precompiledPath,
         reporter: other._reporter ?? _reporter,
         pubServePort: (other.pubServeUrl ?? pubServeUrl)?.port,
         concurrency: other._concurrency ?? _concurrency,
         shardIndex: other.shardIndex ?? shardIndex,
         totalShards: other.totalShards ?? totalShards,
         timeout: timeout.merge(other.timeout),
         patterns: patterns.union(other.patterns),
@@ skipping 22 matching lines @@
       bool help,
       bool version,
       bool verboseTrace,
       bool jsTrace,
       bool skip,
       String skipReason,
       bool runSkipped,
       PlatformSelector testOn,
       bool pauseAfterLoad,
       bool color,
-      String packageRoot,
       String dart2jsPath,
       Iterable<String> dart2jsArgs,
       String precompiledPath,
       String reporter,
       int pubServePort,
       int concurrency,
       int shardIndex,
       int totalShards,
       Timeout timeout,
       Iterable<Pattern> patterns,
@@ skipping 11 matching lines @@
         help: help ?? _help,
         version: version ?? _version,
         verboseTrace: verboseTrace ?? _verboseTrace,
         jsTrace: jsTrace ?? _jsTrace,
         skip: skip ?? _skip,
         skipReason: skipReason ?? this.skipReason,
         runSkipped: runSkipped ?? _runSkipped,
         testOn: testOn ?? this.testOn,
         pauseAfterLoad: pauseAfterLoad ?? _pauseAfterLoad,
         color: color ?? _color,
-        packageRoot: packageRoot ?? _packageRoot,
         dart2jsPath: dart2jsPath ?? _dart2jsPath,
         dart2jsArgs: dart2jsArgs?.toList() ?? this.dart2jsArgs,
         precompiledPath: precompiledPath ?? this.precompiledPath,
         reporter: reporter ?? _reporter,
         pubServePort: pubServePort ?? pubServeUrl?.port,
         concurrency: concurrency ?? _concurrency,
         shardIndex: shardIndex ?? this.shardIndex,
         totalShards: totalShards ?? this.totalShards,
         timeout: timeout ?? this.timeout,
         patterns: patterns ?? this.patterns,
@@ skipping 11 matching lines @@
 
   /// Merges two maps whose values are [Configuration]s.
   ///
   /// Any overlapping keys in the maps have their configurations merged in the
   /// returned map.
   Map<Object, Configuration> _mergeConfigMaps(Map<Object, Configuration> map1,
           Map<Object, Configuration> map2) =>
       mergeMaps(map1, map2,
           value: (config1, config2) => config1.merge(config2));
 }