update code completion suggestion relevance based on common usage

pkg/analysis_server/test/services/completion/completion_test_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.util;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' as protocol show Element,
     ElementKind;
 import 'package:analysis_server/src/protocol.dart' hide Element, ElementKind;
+import 'package:analysis_server/src/services/completion/common_usage_computer.dart';
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_cache.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analysis_server/src/services/completion/imported_computer.dart';
 import 'package:analysis_server/src/services/completion/invocation_computer.dart';
 import 'package:analysis_server/src/services/index/index.dart';
 import 'package:analysis_server/src/services/index/local_memory_index.dart';
 import 'package:analysis_server/src/services/search/search_engine_internal.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 421 matching lines @@
     }
   }
 
   bool computeFast() {
     _computeFastCalled = true;
     _completionManager = new DartCompletionManager(
         context,
         searchEngine,
         testSource,
         cache,
-        [computer]);
+        [computer],
+        new MockCommonUsageComputer());
     var result = _completionManager.computeFast(request);
     expect(request.replacementOffset, isNotNull);
     expect(request.replacementLength, isNotNull);
     return result.isEmpty;
   }
 
   Future computeFull(assertFunction(bool result), {bool fullAnalysis: true}) {
     if (!_computeFastCalled) {
       expect(computeFast(), isFalse);
     }
@@ skipping 2025 matching lines @@
       assertNotSuggested('m');
       assertNotSuggested('_n');
       assertNotSuggested('a');
       assertNotSuggested('A');
       assertNotSuggested('X');
       assertNotSuggested('Object');
       assertNotSuggested('==');
     });
   }
 
+  test_new_instance() {
+    addTestSource('import "dart:math"; class A {x() {new Random().^}}');
+    computeFast();
+    return computeFull((bool result) {
+      assertSuggestInvocationMethod('nextBool', 'Random', 'bool');
+      assertSuggestInvocationMethod('nextDouble', 'Random', 'double');
+      assertSuggestInvocationMethod('nextInt', 'Random', 'int');
+      assertNotSuggested('Random');
+      assertNotSuggested('Object');
+      assertNotSuggested('A');
+    });
+  }
+
   test_partFile_TypeName() {
     // SimpleIdentifier  TypeName  ConstructorName
     addSource('/testB.dart', '''
       lib B;
       int T1;
       F1() { }
       class X {X.c(); X._d(); z() {}}''');
     addSource('/testA.dart', '''
       library libA;
       import "/testB.dart";
@@ skipping 458 matching lines @@
       assertNotSuggested('bar2');
       assertNotSuggested('_B');
       assertSuggestLocalClass('Y');
       assertSuggestLocalClass('C');
       assertSuggestLocalVariable('f', null);
       assertNotSuggested('x');
       assertNotSuggested('e');
     });
   }
 }
+
+class MockCommonUsageComputer implements CommonUsageComputer {
+  @override
+  void computeFast(DartCompletionRequest request) {
+  }
+
+  @override
+  void computeFull(DartCompletionRequest request) {
+  }
+}