Use helper methods for running pub.

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

Index: sdk/lib/_internal/pub/test/test_pub.dart
diff --git a/sdk/lib/_internal/pub/test/test_pub.dart b/sdk/lib/_internal/pub/test/test_pub.dart
index 50f6343150c1abb343bd5845febb3aef2678cfb0..c9ee7d2093ec9a3d35702a5a82ce1e405eb73ea4 100644
--- a/sdk/lib/_internal/pub/test/test_pub.dart
+++ b/sdk/lib/_internal/pub/test/test_pub.dart
@@ -238,15 +238,13 @@ bool _abortScheduled = false;
 /// Enum identifying a pub command that can be run with a well-defined success
 /// output.
 class RunCommand {
-  static final install = new RunCommand('install',
-      new RegExp("Dependencies installed!\$"));
-
-  static final update = new RunCommand('update',
-      new RegExp("Dependencies updated!\$"));
+  static final install = new RunCommand('install', 'installed');
+  static final update = new RunCommand('update', 'updated');
 
   final String name;
   final RegExp success;
-  RunCommand(this.name, this.success);
+  RunCommand(this.name, String verb)
+      : success = new RegExp("Dependencies $verb!\$");
 }
 
 /// Many tests validate behavior that is the same between pub install and