report invalid param if offset is out of bounds

pkg/analysis_server/test/domain_completion_test.dart

 // Copyright (c) 2014, 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.domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/analysis_server.dart';
@@ skipping 667 matching lines @@
       assertHasResult(CompletionSuggestionKind.INVOCATION, 'b',
           relevance: DART_RELEVANCE_LOCAL_VARIABLE);
       assertHasResult(CompletionSuggestionKind.INVOCATION, 'x',
           relevance: DART_RELEVANCE_LOCAL_METHOD);
       assertHasResult(CompletionSuggestionKind.INVOCATION, 'DateTime');
     });
   }
 
   test_offset_past_eof() {
     addTestFile('main() { }', offset: 300);
-    return getSuggestions().then((_) {
-      expect(replacementOffset, equals(300));
-      expect(replacementLength, equals(0));
-      expect(suggestionsDone, true);
-      expect(suggestions.length, 0);
-    });
+    Request request =
+        new CompletionGetSuggestionsParams(testFile, completionOffset)
+            .toRequest('0');
+    Response response = handler.handleRequest(request);
+    expect(response.id, '0');
+    expect(response.error.code, RequestErrorCode.INVALID_PARAMETER);
   }
 
   test_overrides() {
     addFile('/libA.dart', 'class A {m() {}}');
     addTestFile('''
 import '/libA.dart';
 class B extends A {m() {^}}
 ''');
     return getSuggestions().then((_) {
       expect(replacementOffset, equals(completionOffset));
@@ skipping 285 matching lines @@
 }
     ''');
     await waitForTasksFinished();
     Request request =
         new CompletionGetSuggestionsParams(testFile, 0).toRequest('0');
     Response response = handler.handleRequest(request);
     expect(response.error, isNotNull);
     expect(response.error.code, RequestErrorCode.NO_INDEX_GENERATED);
   }
 }