Fix tests to verify defaultArgListString specified as null are null.

pkg/analysis_server/test/services/completion/dart/completion_contributor_util.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.services.completion.dart.util;
 
 import 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart' as protocol
     show Element, ElementKind;
@@ skipping 19 matching lines @@
 import '../../../abstract_context.dart';
 import '../../correction/flutter_util.dart';
 
 int suggestionComparator(CompletionSuggestion s1, CompletionSuggestion s2) {
   String c1 = s1.completion.toLowerCase();
   String c2 = s2.completion.toLowerCase();
   return c1.compareTo(c2);
 }
 
 abstract class DartCompletionContributorTest extends AbstractContextTest {
+  static const String _UNCHECKED = '__UNCHECKED__';
   Index index;
   SearchEngineImpl searchEngine;
   String testFile = '/completionTest.dart';
   Source testSource;
   int completionOffset;
   int replacementOffset;
   int replacementLength;
   DartCompletionContributor contributor;
   DartCompletionRequest request;
   List<CompletionSuggestion> suggestions;
@@ skipping 62 matching lines @@
       {CompletionSuggestionKind csKind: CompletionSuggestionKind.INVOCATION,
       int relevance: DART_RELEVANCE_DEFAULT,
       String importUri,
       protocol.ElementKind elemKind: null,
       bool isDeprecated: false,
       bool isPotential: false,
       String elemFile,
       int elemOffset,
       String paramName,
       String paramType,
-      String defaultArgListString,
+      String defaultArgListString: _UNCHECKED,
       List<int> defaultArgumentListTextRanges}) {
     CompletionSuggestion cs =
         getSuggest(completion: completion, csKind: csKind, elemKind: elemKind);
     if (cs == null) {
       failedCompletion('expected $completion $csKind $elemKind', suggestions);
     }
     expect(cs.kind, equals(csKind));
     if (isDeprecated) {
       expect(cs.relevance, equals(DART_RELEVANCE_LOW));
     } else {
@@ skipping 17 matching lines @@
     }
     if (elemOffset != null) {
       expect(cs.element.location.offset, elemOffset);
     }
     if (paramName != null) {
       expect(cs.parameterName, paramName);
     }
     if (paramType != null) {
       expect(cs.parameterType, paramType);
     }
-    if (defaultArgListString != null) {
+    if (defaultArgListString != _UNCHECKED) {
       expect(cs.defaultArgumentListString, defaultArgListString);
     }
     if (defaultArgumentListTextRanges != null) {
       expect(cs.defaultArgumentListTextRanges, defaultArgumentListTextRanges);
     }
     return cs;
   }
 
   CompletionSuggestion assertSuggestClass(String name,
       {int relevance: DART_RELEVANCE_DEFAULT,
@@ skipping 32 matching lines @@
     expect(element.parameters, isNull);
     expect(element.returnType, isNull);
     assertHasNoParameterInfo(cs);
     return cs;
   }
 
   CompletionSuggestion assertSuggestConstructor(String name,
       {int relevance: DART_RELEVANCE_DEFAULT,
       String importUri,
       int elemOffset,
-      String defaultArgListString,
+      String defaultArgListString: _UNCHECKED,
       List<int> defaultArgumentListTextRanges}) {
     CompletionSuggestion cs = assertSuggest(name,
         relevance: relevance,
         importUri: importUri,
         elemOffset: elemOffset,
         defaultArgListString: defaultArgListString,
         defaultArgumentListTextRanges: defaultArgumentListTextRanges);
     protocol.Element element = cs.element;
     expect(element, isNotNull);
     expect(element.kind, equals(protocol.ElementKind.CONSTRUCTOR));
@@ skipping 43 matching lines @@
     expect(element.returnType, type != null ? type : 'dynamic');
     assertHasNoParameterInfo(cs);
     return cs;
   }
 
   CompletionSuggestion assertSuggestFunction(String name, String returnType,
       {CompletionSuggestionKind kind: CompletionSuggestionKind.INVOCATION,
       bool isDeprecated: false,
       int relevance: DART_RELEVANCE_DEFAULT,
       String importUri,
-      String defaultArgListString,
+      String defaultArgListString: _UNCHECKED,
       List<int> defaultArgumentListTextRanges}) {
     CompletionSuggestion cs = assertSuggest(name,
         csKind: kind,
         relevance: relevance,
         importUri: importUri,
         isDeprecated: isDeprecated,
         defaultArgListString: defaultArgListString,
         defaultArgumentListTextRanges: defaultArgumentListTextRanges);
     if (returnType != null) {
       expect(cs.returnType, returnType);
@@ skipping 75 matching lines @@
     assertHasNoParameterInfo(cs);
     return cs;
   }
 
   CompletionSuggestion assertSuggestMethod(
       String name, String declaringType, String returnType,
       {int relevance: DART_RELEVANCE_DEFAULT,
       String importUri,
       CompletionSuggestionKind kind: CompletionSuggestionKind.INVOCATION,
       bool isDeprecated: false,
-      String defaultArgListString,
+      String defaultArgListString: _UNCHECKED,
       List<int> defaultArgumentListTextRanges}) {
     CompletionSuggestion cs = assertSuggest(name,
         csKind: kind,
         relevance: relevance,
         importUri: importUri,
         isDeprecated: isDeprecated,
         defaultArgListString: defaultArgListString,
         defaultArgumentListTextRanges: defaultArgumentListTextRanges);
     expect(cs.declaringType, equals(declaringType));
     expect(cs.returnType, returnType != null ? returnType : 'dynamic');
@@ skipping 250 matching lines @@
 
   @override
   void setUp() {
     super.setUp();
     index = createMemoryIndex();
     searchEngine =
         new SearchEngineImpl(index, (_) => new AstProviderForContext(context));
     contributor = createContributor();
   }
 }