Make LockFile immutable.

test/test_pub.dart

 // Copyright (c) 2013, 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.
 
 /// Test infrastructure for testing pub.
 ///
 /// Unlike typical unit tests, most pub tests are integration tests that stage
 /// some stuff on the file system, run pub, and then validate the results. This
 /// library provides an API to build tests like that.
 library test_pub;
@@ skipping 673 matching lines @@
     Iterable<d.Descriptor> contents, {Iterable<String> pkg,
     Map<String, String> hosted}) {
   // Start the server so we know what port to use in the cache directory name.
   serveNoPackages();
 
   // Create the package in the hosted cache.
   d.hostedCache([
     d.dir("$package-$version", contents)
   ]).create();
 
-  var lockFile = _createLockFile(pkg: pkg, hosted: hosted);
-
-  // Add the root package to the lockfile.
-  var id = new PackageId(package, "hosted", new Version.parse(version),
-      package);
-  lockFile.packages[package] = id;
-
   // Write the lockfile to the global cache.
   var sources = new SourceRegistry();
   sources.register(new HostedSource());
   sources.register(new PathSource());
 
+  var lockFile = _createLockFile(sources, pkg: pkg, hosted: hosted);
+
+  // Add the root package to the lockfile.
+  var id = new PackageId(package, "hosted", new Version.parse(version),
+      package);
+  lockFile = lockFile.setPackage(id);
+
   d.dir(cachePath, [
     d.dir("global_packages", [
-      d.file("$package.lock", lockFile.serialize(null, sources))
+      d.file("$package.lock", lockFile.serialize(null))
     ])
   ]).create();
 }
 
 /// Creates a lock file for [package] without running `pub get`.
 ///
 /// [sandbox] is a list of path dependencies to be found in the sandbox
 /// directory. [pkg] is a list of packages in the Dart repo's "pkg" directory;
 /// each package listed here and all its dependencies will be linked to the
 /// version in the Dart repo.
 ///
 /// [hosted] is a list of package names to version strings for dependencies on
 /// hosted packages.
 void createLockFile(String package, {Iterable<String> sandbox,
     Iterable<String> pkg, Map<String, String> hosted}) {
-  var lockFile = _createLockFile(sandbox: sandbox, pkg: pkg, hosted: hosted);
-
   var sources = new SourceRegistry();
   sources.register(new HostedSource());
   sources.register(new PathSource());
 
-  d.file(p.join(package, 'pubspec.lock'),
-      lockFile.serialize(null, sources)).create();
+  var lockFile = _createLockFile(sources,
+      sandbox: sandbox, pkg: pkg, hosted: hosted);
+
+  d.file(p.join(package, 'pubspec.lock'), lockFile.serialize(null)).create();
 }
 
 /// Creates a lock file for [package] without running `pub get`.
 ///
 /// [sandbox] is a list of path dependencies to be found in the sandbox
 /// directory. [pkg] is a list of packages in the Dart repo's "pkg" directory;
 /// each package listed here and all its dependencies will be linked to the
 /// version in the Dart repo.
 ///
 /// [hosted] is a list of package names to version strings for dependencies on
 /// hosted packages.
-LockFile _createLockFile({Iterable<String> sandbox,
-Iterable<String> pkg, Map<String, String> hosted}) {
+LockFile _createLockFile(SourceRegistry sources, {Iterable<String> sandbox,
+    Iterable<String> pkg, Map<String, String> hosted}) {
   var dependencies = {};
 
   if (sandbox != null) {
     for (var package in sandbox) {
       dependencies[package] = '../$package';
     }
   }
 
   if (pkg != null) {
     _addPackage(String package) {
@@ skipping 16 matching lines @@
       var pubspec = loadYaml(
           readTextFile(p.join(path, 'pubspec.yaml')));
       var packageDeps = pubspec['dependencies'];
       if (packageDeps == null) return;
       packageDeps.keys.forEach(_addPackage);
     }
 
     pkg.forEach(_addPackage);
   }
 
-  var lockFile = new LockFile.empty();
-  dependencies.forEach((name, dependencyPath) {
-    var id = new PackageId(name, 'path', new Version(0, 0, 0), {
+  var packages = dependencies.keys.map((name) {
+    var dependencyPath = dependencies[name];
+    return new PackageId(name, 'path', new Version(0, 0, 0), {
       'path': dependencyPath,
       'relative': p.isRelative(dependencyPath)
     });
-    lockFile.packages[name] = id;
-  });
+  }).toList();
 
   if (hosted != null) {
     hosted.forEach((name, version) {
       var id = new PackageId(name, 'hosted', new Version.parse(version), name);
-      lockFile.packages[name] = id;
+      packages.add(id);
     });
   }
 
-  return lockFile;
+  return new LockFile(packages, sources);
 }
 
 /// Returns the path to the version of [package] used by pub.
 String packagePath(String package) {
   if (runningFromDartRepo) {
     return dirExists(p.join(dartRepoRoot, 'pkg', package))
         ? p.join(dartRepoRoot, 'pkg', package)
         : p.join(dartRepoRoot, 'third_party', 'pkg', package);
   }
 
@@ skipping 199 matching lines @@
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     return description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
 
 /// A [StreamMatcher] that matches multiple lines of output.
 StreamMatcher emitsLines(String output) => inOrder(output.split("\n"));