Make binstubs run snapshots directly when possible.

sdk/lib/_internal/pub_generated/test/test_pub.dart

 library test_pub;
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
 import 'package:http/testing.dart';
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_stream.dart';
@@ skipping 262 matching lines @@
   return startPub(args: args, tokenEndpoint: tokenEndpoint);
 }
 void confirmPublish(ScheduledProcess pub) {
   pub.stdout.expect(startsWith('Publishing test_pkg 1.0.0 to '));
   pub.stdout.expect(
       emitsLines(
           "|-- LICENSE\n" "|-- lib\n" "|   '-- test_pkg.dart\n" "'-- pubspec.yaml\n" "\n"
               "Looks great! Are you ready to upload your package (y/n)?"));
   pub.writeLine("y");
 }
+String _pathInSandbox(String relPath) {
+  return p.join(p.absolute(sandboxDir), relPath);
+}
+Map getPubTestEnvironment([Uri tokenEndpoint]) {
+  var environment = {};
+  environment['_PUB_TESTING'] = 'true';
+  environment['PUB_CACHE'] = _pathInSandbox(cachePath);
+  environment['_PUB_TEST_SDK_VERSION'] = "0.1.2+3";
+  if (tokenEndpoint != null) {
+    environment['_PUB_TEST_TOKEN_ENDPOINT'] = tokenEndpoint.toString();
+  }
+  return environment;
+}
 ScheduledProcess startPub({List args, Future<Uri> tokenEndpoint}) {
-  String pathInSandbox(String relPath) {
-    return p.join(p.absolute(sandboxDir), relPath);
-  }
-  ensureDir(pathInSandbox(appPath));
+  ensureDir(_pathInSandbox(appPath));
   var dartBin = Platform.executable;
   if (dartBin.contains(Platform.pathSeparator)) {
     dartBin = p.absolute(dartBin);
   }
   var pubPath = p.join(p.dirname(dartBin), 'snapshots/pub.dart.snapshot');
   var dartArgs = [pubPath, '--verbose'];
   dartArgs.addAll(args);
   if (tokenEndpoint == null) tokenEndpoint = new Future.value();
   var environmentFuture = tokenEndpoint.then((tokenEndpoint) {
-    var environment = {};
-    environment['_PUB_TESTING'] = 'true';
-    environment['PUB_CACHE'] = pathInSandbox(cachePath);
-    environment['_PUB_TEST_SDK_VERSION'] = "0.1.2+3";
-    if (tokenEndpoint != null) {
-      environment['_PUB_TEST_TOKEN_ENDPOINT'] = tokenEndpoint.toString();
-    }
+    var environment = getPubTestEnvironment(tokenEndpoint);
     if (_hasServer) {
       return port.then((p) {
         environment['PUB_HOSTED_URL'] = "http://localhost:$p";
         return environment;
       });
     }
     return environment;
   });
   return new PubProcess.start(
       dartBin,
       dartArgs,
       environment: environmentFuture,
-      workingDirectory: pathInSandbox(appPath),
+      workingDirectory: _pathInSandbox(appPath),
       description: args.isEmpty ? 'pub' : 'pub ${args.first}');
 }
 class PubProcess extends ScheduledProcess {
   Stream<Pair<log.Level, String>> _log;
   Stream<String> _stdout;
   Stream<String> _stderr;
   PubProcess.start(executable, arguments, {workingDirectory, environment,
       String description, Encoding encoding: UTF8})
       : super.start(
           executable,
@@ skipping 269 matching lines @@
   bool matches(item, Map matchState) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
   Description describe(Description description) {
     return description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
 StreamMatcher emitsLines(String output) => inOrder(output.split("\n"));