Use an auto-generated pub snapshot for tests.

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;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
 
+import 'package:crypto/crypto.dart';
 import 'package:http/testing.dart';
 import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart' hide fail;
 import 'package:shelf/shelf.dart' as shelf;
 import 'package:shelf/shelf_io.dart' as shelf_io;
 import 'package:unittest/compact_vm_config.dart';
 import 'package:yaml/yaml.dart';
 
 import '../lib/src/entrypoint.dart';
 import '../lib/src/exit_codes.dart' as exit_codes;
 // TODO(rnystrom): Using "gitlib" as the prefix here is ugly, but "git" collides
 // with the git descriptor method. Maybe we should try to clean up the top level
 // scope a bit?
 import '../lib/src/git.dart' as gitlib;
 import '../lib/src/http.dart';
 import '../lib/src/io.dart';
 import '../lib/src/lock_file.dart';
 import '../lib/src/log.dart' as log;
 import '../lib/src/package.dart';
 import '../lib/src/pubspec.dart';
+import '../lib/src/sdk.dart' as sdk;
 import '../lib/src/source/hosted.dart';
 import '../lib/src/source/path.dart';
 import '../lib/src/source_registry.dart';
 import '../lib/src/system_cache.dart';
 import '../lib/src/utils.dart';
 import '../lib/src/validator.dart';
 import 'descriptor.dart' as d;
 import 'serve_packages.dart';
 
 export 'serve_packages.dart';
@@ skipping 461 matching lines @@
   // Find a Dart executable we can use to spawn. Use the same one that was
   // used to run this script itself.
   var dartBin = Platform.executable;
 
   // If the executable looks like a path, get its full path. That way we
   // can still find it when we spawn it with a different working directory.
   if (dartBin.contains(Platform.pathSeparator)) {
     dartBin = p.absolute(dartBin);
   }
 
-  // Always run pub from a snapshot. Since we require the SDK to be built, the
-  // snapshot should be there. Note that this *does* mean that the snapshot has
-  // to be manually updated when changing code before running the tests.
-  // Otherwise, you will test against stale data.
-  //
-  // Using the snapshot makes running the tests much faster, which is why we
-  // make this trade-off.
-  var pubPath = p.join(p.dirname(dartBin), 'snapshots/pub.dart.snapshot');
+  // Always run pub from a snapshot. Using the snapshot makes running the tests
+  // much faster, especially when multiple tests are run at once.
+  var pubPath = p.absolute(p.join(pubRoot, '.pub/pub.test.snapshot'));
   var dartArgs = [pubPath, '--verbose'];
   dartArgs.addAll(args);
 
   if (tokenEndpoint == null) tokenEndpoint = new Future.value();
   var environmentFuture = tokenEndpoint
       .then((tokenEndpoint) => getPubTestEnvironment(tokenEndpoint))
       .then((pubEnvironment) {
     if (environment != null) pubEnvironment.addAll(environment);
     return pubEnvironment;
   });
 
+  _ensureSnapshot();
+
   return new PubProcess.start(dartBin, dartArgs, environment: environmentFuture,
       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 snapshotPath = p.join(pubRoot, '.pub', 'pub.test.snapshot');
+  var hashPath = p.join(pubRoot, '.pub', 'pub.hash');
+  var versionPath = p.join(pubRoot, '.pub', 'pub.version');
+  if (fileExists(hashPath) && fileExists(versionPath)) {
+    var oldHash = readTextFile(hashPath);
+    var oldVersion = readTextFile(versionPath);
+
+    if (oldHash == hash && oldVersion == version && fileExists(snapshotPath)) {
+      return;
+    }
+  }
+
+  var dartSnapshot = runProcessSync(Platform.executable, [
+    '--snapshot=$snapshotPath',
+    p.join(pubRoot, 'bin', 'pub.dart')
+  ]);
+  if (dartSnapshot.exitCode != 0) throw "Failed to run dart --snapshot.";
+
+  writeTextFile(hashPath, hash);
+  writeTextFile(versionPath, version);
+}
+
+/// Returns a hash that encapsulates the current state of the repo.
+String _hashChanges() {
+  var hash = new SHA1();
+
+  // Include the current Git commit.
+  hash.add(UTF8.encode(gitlib.runSync(['rev-parse', 'HEAD']).first));
+
+  // Include the changes in lib and bin relative to the current Git commit.
+  var tracked = gitlib.runSync(['diff-index', '--patch', 'HEAD', 'lib', 'bin']);
+  for (var line in tracked) {
+    hash.add(UTF8.encode("$line\n"));
+  }
+
+  // Include the full contents of non-ignored files in lib and bin that aren't
+  // tracked by Git.
+  var untracked = gitlib.runSync(
+      ['ls-files', '--others', '--exclude-standard', 'lib', 'bin']);
+  for (var path in untracked) {
+    hash.add(readBinaryFile(path));
+  }
+
+  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 411 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"));