Show better error messages in network failures.

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/lock_file.dart';
 import '../../pub/package.dart';
 import '../../pub/pubspec.dart';
 import '../../pub/root_source.dart';
 import '../../pub/source.dart';
 import '../../pub/source_registry.dart';
+import '../../pub/system_cache.dart';
 import '../../pub/utils.dart';
 import '../../pub/version.dart';
 import '../../pub/version_solver.dart';
 import '../../../pkg/unittest/lib/unittest.dart';
 
 final noVersion = 'no version';
 final disjointConstraint = 'disjoint';
 final sourceMismatch = 'source mismatch';
 final descriptionMismatch = 'description mismatch';
 final couldNotSolve = 'unsolved';
@@ skipping 320 matching lines @@
        "    is a DisjointConstraintException");
     var isSourceMismatchException =
         predicate((x)=> x is SourceMismatchException,
             "is a SourceMismatchException");
     var isDescriptionMismatchException =
         predicate((x)=> x is DescriptionMismatchException,
             "is a DescriptionMismatchException");
     var isCouldNotSolveException = predicate((x)=> x is CouldNotSolveException,
             "is a CouldNotSolveException");
 
-    var sources = new SourceRegistry();
+    var cache = new SystemCache('.');
     source1 = new MockSource('mock1');
     source2 = new MockSource('mock2');
     versionlessSource = new MockVersionlessSource();
-    sources.register(source1);
-    sources.register(source2);
-    sources.register(versionlessSource);
-    sources.setDefault(source1.name);
+    cache.register(source1);
+    cache.register(source2);
+    cache.register(versionlessSource);
+    cache.sources.setDefault(source1.name);
 
     // Build the test package graph.
     var root;
     packages.forEach((nameVersion, dependencies) {
       var parsed = parseSource(nameVersion);
       nameVersion = parsed.first;
       var source = parsed.last;
 
       var parts = nameVersion.split(' ');
       var name = parts[0];
       var version = parts[1];
 
       var package = source1.mockPackage(name, version, dependencies);
       if (name == 'myapp') {
         // Don't add the root package to the server, so we can verify that Pub
         // doesn't try to look up information about the local package on the
         // remote server.
         root = package;
         rootSource = new RootSource(root);
-        sources.register(rootSource);
+        cache.register(rootSource);
       } else {
         source.addPackage(package);
       }
     });
 
     // Clean up the expectation.
     if (result != null) {
       var newResult = {};
       result.forEach((name, version) {
         var parsed = parseSource(name);
         name = parsed.first;
         var source = parsed.last;
         version = new Version.parse(version);
         newResult[name] = new PackageId(name, source, version, name);
       });
       result = newResult;
     }
 
     var realLockFile = new LockFile.empty();
     if (lockfile != null) {
       lockfile.forEach((name, version) {
         version = new Version.parse(version);
         realLockFile.packages[name] =
           new PackageId(name, source1, version, name);
       });
     }
 
     // Resolve the versions.
-    var future = resolveVersions(sources, root, realLockFile);
+    var future = resolveVersions(cache.sources, root, realLockFile);
 
     if (result != null) {
       expect(future, completion(predicate((actualResult) {
         for (var actualId in actualResult) {
           if (!result.containsKey(actualId.name)) return false;
           var expectedId = result.remove(actualId.name);
           if (actualId != expectedId) return false;
         }
         return result.isEmpty;
       }, 'packages to match $result')));
@@ skipping 115 matching lines @@
   var match = new RegExp(r"(.*) from (.*)").firstMatch(name);
   if (match == null) return new Pair<String, Source>(name, source1);
   switch (match[2]) {
   case 'mock1': return new Pair<String, Source>(match[1], source1);
   case 'mock2': return new Pair<String, Source>(match[1], source2);
   case 'root': return new Pair<String, Source>(match[1], rootSource);
   case 'versionless':
     return new Pair<String, Source>(match[1], versionlessSource);
   }
 }