Strong-mode error code validation "enum" (#25117).

pkg/analyzer/test/src/task/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.src.task.options_test;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/source/analysis_options_provider.dart';
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisContextImpl;
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 266 matching lines @@
   test_analyzer_language_unsupported_value() {
     validate(
         '''
 analyzer:
   language:
     enableSuperMixins: foo
 ''',
         [AnalysisOptionsWarningCode.UNSUPPORTED_VALUE]);
   }
 
+  test_analyzer_strong_mode_error_code_supported() {
+    validate(
+        '''
+analyzer:
+  errors:
+    strong_mode_assignment_cast: ignore
+''',
+        []);
+  }
+
   test_analyzer_supported_exclude() {
     validate(
         '''
 analyzer:
   exclude:
     - test/_data/p4/lib/lib1.dart
     ''',
         []);
   }
 
@@ skipping 43 matching lines @@
         [AnalysisOptionsWarningCode.UNSUPPORTED_OPTION_WITH_LEGAL_VALUE]);
   }
 
   void validate(String source, List<AnalysisOptionsErrorCode> expected) {
     var options = optionsProvider.getOptionsFromString(source);
     var errors = validator.validate(options);
     expect(errors.map((AnalysisError e) => e.errorCode),
         unorderedEquals(expected));
   }
 }