Factor in the Dart repo's state for snapshotting.

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 541 matching lines @@
       workingDirectory: _pathInSandbox(appPath),
       description: args.isEmpty ? 'pub' : 'pub ${args.first}');
 }
 
 /// Ensure that a snapshot of the current pub source exists at
 /// ".pub/pub.snapshot".
 void _ensureSnapshot() {
   ensureDir(p.join(pubRoot, '.pub'));
 
   var version = sdk.version.toString();
-  var hash = _hashChanges();
+  var pubHash = _hashChanges();
+  var dartHash = runningFromDartRepo ? _hashExecutable() : null;
 
   var snapshotPath = p.join(pubRoot, '.pub', 'pub.test.snapshot');
-  var hashPath = p.join(pubRoot, '.pub', 'pub.hash');
+  var pubHashPath = p.join(pubRoot, '.pub', 'pub.hash');
+  var dartHashPath = p.join(pubRoot, '.pub', 'dart.hash');
   var versionPath = p.join(pubRoot, '.pub', 'pub.version');
-  if (fileExists(hashPath) && fileExists(versionPath)) {
-    var oldHash = readTextFile(hashPath);
+  if (fileExists(pubHashPath) && fileExists(versionPath) &&
+      (!runningFromDartRepo || fileExists(dartHashPath))) {
+    var oldPubHash = readTextFile(pubHashPath);
+    var oldDartHash = runningFromDartRepo ? readTextFile(dartHashPath) : null;
     var oldVersion = readTextFile(versionPath);
 
-    if (oldHash == hash && oldVersion == version && fileExists(snapshotPath)) {
+    if (oldPubHash == pubHash && oldDartHash == dartHash &&
+        oldVersion == version && fileExists(snapshotPath)) {
       return;
     }
   }
 
   var args = ['--snapshot=$snapshotPath'];
   if (Platform.packageRoot.isNotEmpty) {
     args.add('--package-root=${Platform.packageRoot}');
   }
   args.add(p.join(pubRoot, 'bin', 'pub.dart'));
 
   var dartSnapshot = runProcessSync(Platform.executable, args);
   if (dartSnapshot.exitCode != 0) throw "Failed to run dart --snapshot.";
 
-  writeTextFile(hashPath, hash);
+  writeTextFile(pubHashPath, pubHash);
+  if (runningFromDartRepo) writeTextFile(dartHashPath, dartHash);
   writeTextFile(versionPath, version);
 }
 
 /// Returns a hash that encapsulates the current state of the repo.
 String _hashChanges() {
   var hash = new SHA1();
 
   // Include the current Git commit.
   hash.add(UTF8.encode(
       gitlib.runSync(['rev-parse', 'HEAD'], workingDir: pubRoot).first));
@@ skipping 10 matching lines @@
   var untracked = gitlib.runSync(
       ['ls-files', '--others', '--exclude-standard', 'lib', 'bin'],
       workingDir: pubRoot);
   for (var path in untracked) {
     hash.add(readBinaryFile(path));
   }
 
   return CryptoUtils.bytesToHex(hash.close());
 }
 
+/// Return a SHA1 hash of the Dart executable used to run this script.
+///
+/// This is used when running within the Dart repo to ensure that the snapshot
+/// is invalidated when the executable changes.
+String _hashExecutable() {
+  var hash = new SHA1();
+  hash.add(new File(Platform.executable).readAsBytesSync());
+  return CryptoUtils.bytesToHex(hash.close());
+}
+
 /// A subclass of [ScheduledProcess] that parses pub's verbose logging output
 /// and makes [stdout] and [stderr] work as though pub weren't running in
 /// verbose mode.
 class PubProcess extends ScheduledProcess {
   Stream<Pair<log.Level, String>> _log;
   Stream<String> _stdout;
   Stream<String> _stderr;
 
   PubProcess.start(executable, arguments,
       {workingDirectory, environment, String description,
@@ skipping 423 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"));