Use an auto-generated pub snapshot for tests.

lib/src/git.dart

 // Copyright (c) 2012, 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.
 
 /// Helper functionality for invoking Git.
 library pub.git;
 
 import 'dart:async';
 import 'dart:io';
 
@@ skipping 58 matching lines @@
         "Please ensure Git is correctly installed.");
   }
 
   var result = runProcessSync(_gitCommand, args,
       workingDir: workingDir,
       environment: environment);
   if (!result.success) throw new GitException(args, result.stderr.join("\n"));
   return result.stdout;
 }
 
+/// Starts a git process and returns it.
+Future<PubProcess> start(List<String> args,
+    {String workingDir, Map<String, String> environment}) {
+  if (!isInstalled) {
+    fail("Cannot find a Git executable.\n"
+        "Please ensure Git is correctly installed.");
+  }
+
+  return startProcess(_gitCommand, args, workingDir: workingDir,
+      environment: environment);
+}
+
 /// Returns the name of the git command-line app, or null if Git could not be
 /// found on the user's PATH.
 String get _gitCommand {
   if (_commandCache != null) return _commandCache;
 
   var command;
   if (_tryGitCommand("git")) {
     _commandCache = "git";
   } else if (_tryGitCommand("git.cmd")){
     _commandCache = "git.cmd";
@@ skipping 13 matching lines @@
     var result = runProcessSync(command, ["--version"]);
     var regexp = new RegExp("^git version");
     return result.stdout.length == 1 && regexp.hasMatch(result.stdout.single);
   } on ProcessException catch (error, stackTrace) {
     var chain = new Chain.forTrace(stackTrace);
     // If the process failed, they probably don't have it.
     log.message('Git command is not "$command": $error\n$chain');
     return false;
   }
 }