Set ContentCache for created AnalysisContext(s) to control its view of the world.

pkg/analyzer/lib/src/generated/source.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 analyzer.src.generated.source;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/file_system/file_system.dart';
@@ skipping 404 matching lines @@
   @override
   bool operator ==(Object other) {
     if (other is NonExistingSource) {
       return other.uriKind == uriKind && other.fullName == fullName;
     }
     return false;
   }
 
   @override
   bool exists() => false;
+
+  @override
+  String toString() => 'NonExistingSource($uri, $fullName)';
 }
 
 /**
  * The interface `ContentReceiver` defines the behavior of objects that can receive the
  * content of a source.
  */
 abstract class Source_ContentReceiver {
   /**
    * Accept the contents of a source.
    *
@@ skipping 318 matching lines @@
   Source resolveAbsolute(Uri uri, [Uri actualUri]);
 
   /**
    * Return an absolute URI that represents the given [source], or `null` if a
    * valid URI cannot be computed.
    *
    * The computation should be based solely on [source.fullName].
    */
   Uri restoreAbsolute(Source source) => null;
 }