Don't try to look up the root package in the default source.

utils/tests/pub/version_solver_test.dart

 // Copyright (c) 2012, 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.
 
 #library('pub_update_test');
 
 #import('dart:io');
 #import('dart:isolate');
 
 #import('../../pub/package.dart');
@@ skipping 174 matching lines @@
     sources.register(source);
     sources.setDefault(source.name);
 
     // Build the test package graph.
     var root;
     packages.forEach((nameVersion, dependencies) {
       var parts = nameVersion.split(' ');
       var name = parts[0];
       var version = parts[1];
       var package = source.mockPackage(name, version, dependencies);
-      if (name == 'myapp') root = package;
+      if (name == 'myapp') {
+        root = package;

[Bob Nystrom, 2012/06/26 23:39:09]

Can you add a comment here that we specifically don't add my app to the source
so that we can catch attempts to look it up?

[nweiz, 2012/06/27 18:05:12]

Done.

+      } else {
+        source.addPackage(package);
+      }
     });
 
     // Clean up the expectation.
     if (result != null) {
       result.forEach((name, version) {
         result[name] = new Version.parse(version);
       });
     }
 
     // Resolve the versions.
@@ skipping 47 matching lines @@
 
   Package mockPackage(String name, String version, Map dependencyStrings) {
     // Build the pubspec dependencies.
     var dependencies = <PackageRef>[];
     dependencyStrings.forEach((name, constraint) {
       dependencies.add(new PackageRef(name, this,
           new VersionConstraint.parse(constraint), name));
     });
 
     var pubspec = new Pubspec(new Version.parse(version), dependencies);
-    var package = new Package.inMemory(name, pubspec);
+    return new Package.inMemory(name, pubspec);
+  }
 
-    _packages.putIfAbsent(name, () => new Map<Version, Package>());
-    _packages[name][package.version] = package;
+  void addPackage(Package package) {
+    _packages.putIfAbsent(package.name, () => new Map<Version, Package>());
+    _packages[package.name][package.version] = package;
     return package;
   }
 }
 
 Future fakeAsync(callback()) {
   var completer = new Completer();
   new Timer(0, (_) {
     completer.complete(callback());
   });
 
   return completer.future;
 }