Switch analysis_server to use 'package:test'.

pkg/analysis_server/test/services/linter/linter_test.dart

 // Copyright (c) 2015, 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 test.services.linter;
 
 import 'package:analysis_server/src/services/linter/linter.dart';
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
+import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
-import 'package:unittest/unittest.dart';
 
 import '../../utils.dart';
 
 main() {
   initializeTestEnvironment();
-  defineReflectiveTests(LinterRuleOptionsValidatorTest);
+  defineReflectiveSuite(() {
+    defineReflectiveTests(LinterRuleOptionsValidatorTest);
+  });
 }
 
 @reflectiveTest
 class LinterRuleOptionsValidatorTest {
   final LinterRuleOptionsValidator validator = new LinterRuleOptionsValidator();
   final AnalysisOptionsProvider optionsProvider = new AnalysisOptionsProvider();
 
   RecordingErrorListener recorder;
   ErrorReporter reporter;
 
@@ skipping 49 matching lines @@
     validator.validate(reporter, options);
     expect(errors.map((AnalysisError e) => e.errorCode),
         unorderedEquals(expected));
   }
 }
 
 class _TestSource implements Source {
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }