Introducing a lint server plugin.

pkg/analysis_server/test/analysis/notification_analysis_options_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.analysis.notification.analysis_options;
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analyzer/src/generated/engine.dart';
@@ skipping 95 matching lines @@
   rules:
     - camel_case_types
 ''');
 
     await pumpEventQueue();
     await waitForTasksFinished();
 
     verifyLintsEnabled(['camel_case_types']);
   }
 
+  test_lint_options_unsupported() async {
+    addOptionsFile('''
+linter:
+  rules:
+    - unsupported
+''');
+
+    addTestFile(testSource);
+    setAnalysisRoot();
+
+    await waitForTasksFinished();
+
+    expect(optionsFileErrors, hasLength(1));
+    expect(optionsFileErrors.first.severity, AnalysisErrorSeverity.WARNING);
+    expect(optionsFileErrors.first.type, AnalysisErrorType.STATIC_WARNING);
+  }
+
   test_options_file_added() async {
     addTestFile(testSource);
     setAnalysisRoot();
 
     await waitForTasksFinished();
 
     // Verify strong-mode disabled.
     verifyStrongMode(enabled: false);
 
     // Clear errors.
@@ skipping 81 matching lines @@
             AnalysisErrorType.STATIC_TYPE_WARNING,
             AnalysisErrorType.COMPILE_TIME_ERROR
           ]));
     } else {
       // Should only produce a hint.
       expect(errors.map((error) => error.type),
           unorderedEquals([AnalysisErrorType.HINT]));
     }
   }
 }