Spit pub tests into smaller suites.

utils/tests/pub/install/git/check_out_branch_test.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.
+
+#library('pub_tests');
+
+#import('dart:io');
+
+#import('../../test_pub.dart');
+#import('../../../../../pkg/unittest/unittest.dart');
+
+main() {
+  test('checks out a package at a specific branch from Git', () {
+    ensureGit();
+
+    var repo = git('foo.git', [
+      libDir('foo', 'foo 1'),
+      libPubspec('foo', '1.0.0')
+    ]);
+    repo.scheduleCreate();
+    repo.scheduleGit(["branch", "old"]);
+
+    git('foo.git', [
+      libDir('foo', 'foo 2'),
+      libPubspec('foo', '1.0.0')
+    ]).scheduleCommit();
+
+    appDir([{"git": {"url": "../foo.git", "ref": "old"}}]).scheduleCreate();
+
+    schedulePub(args: ['install'],
+        output: const RegExp(r"Dependencies installed!$"));
+
+    dir(packagesPath, [
+      dir('foo', [
+        file('foo.dart', 'main() => "foo 1";')
+      ])
+    ]).scheduleValidate();
+
+    run();
+  });
+}