Fix an arg parser test for the analyzer cli.

pkg/analyzer_cli/test/options_test.dart

Index: pkg/analyzer_cli/test/options_test.dart
diff --git a/pkg/analyzer_cli/test/options_test.dart b/pkg/analyzer_cli/test/options_test.dart
index c0ca301e3a07695560dff70238ed27b4a9f6058d..885c22c39b44f2402e2b861acfc303466b7678cd 100644
--- a/pkg/analyzer_cli/test/options_test.dart
+++ b/pkg/analyzer_cli/test/options_test.dart
@@ -122,7 +122,7 @@ main() {
 
       test('package root', () {
         CommandLineOptions options = CommandLineOptions
-            .parse(['--dart-sdk', '.', '-p', 'bar', 'foo.dart']);
+            .parse(['--dart-sdk', '.', '--package-root', 'bar', 'foo.dart']);
         expect(options.packageRootPath, equals('bar'));
       });