Make binstubs run snapshots directly when possible.

sdk/lib/_internal/pub/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 458 matching lines @@
   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");
 }
 
+/// Gets the absolute path to [relPath], which is a relative path in the test
+/// sandbox.
+String _pathInSandbox(String relPath) {
+  return p.join(p.absolute(sandboxDir), relPath);
+}
+
+/// Gets the environment variables used to run pub in a test context.
+Map getPubTestEnvironment([Uri tokenEndpoint]) {
+  var environment = {};
+  environment['_PUB_TESTING'] = 'true';
+  environment['PUB_CACHE'] = _pathInSandbox(cachePath);
+
+  // Ensure a known SDK version is set for the tests that rely on that.
+  environment['_PUB_TEST_SDK_VERSION'] = "0.1.2+3";
+
+  if (tokenEndpoint != null) {
+    environment['_PUB_TEST_TOKEN_ENDPOINT'] =
+      tokenEndpoint.toString();
+  }
+
+  return environment;
+}
+
 /// Starts a Pub process and returns a [ScheduledProcess] that supports
 /// interaction with that process.
 ///
 /// Any futures in [args] will be resolved before the process is started.
 ScheduledProcess startPub({List args, Future<Uri> tokenEndpoint}) {
-  String pathInSandbox(String relPath) {
-    return p.join(p.absolute(sandboxDir), relPath);
-  }
-
-  ensureDir(pathInSandbox(appPath));
+  ensureDir(_pathInSandbox(appPath));
 
   // 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');
   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);
-
-    // Ensure a known SDK version is set for the tests that rely on that.
-    environment['_PUB_TEST_SDK_VERSION'] = "0.1.2+3";
-
-    if (tokenEndpoint != null) {
-      environment['_PUB_TEST_TOKEN_ENDPOINT'] =
-        tokenEndpoint.toString();
-    }
+    var environment = getPubTestEnvironment(tokenEndpoint);
 
     // If there is a server running, tell pub what its URL is so hosted
     // dependencies will look there.
     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}');
 }
 
 /// 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;
@@ skipping 410 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"));