Separate index objects for each analysis context.

pkg/analysis_server/test/services/index2/index2_test.dart

 // Copyright (c) 2016, 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.
 
 import 'package:analysis_server/src/services/index2/index2.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ skipping 162 matching lines @@
 ''');
     List<Location> locations =
         await index.getUnresolvedMemberReferences('test');
     expect(locations, hasLength(4));
     findLocationTest(locations, 'test(); // p-inv-ur-q');
     findLocationTest(locations, 'test = 1; // p-ref-ur-q');
     findLocationTest(locations, 'test += 2; // p-ref-ur-q');
     findLocationTest(locations, 'test); // p-ref-ur-q');
   }
 
+  test_indexUnit_nullUnit() async {
+    index.indexUnit(null);
+  }
+
+  test_indexUnit_nullUnitElement() async {
+    resolveTestUnit('');
+    testUnit.element = null;
+    index.indexUnit(testUnit);
+  }
+
+  test_removeContext() async {
+    _indexTestUnit('''
+class A {}
+''');
+    RegExp regExp = new RegExp(r'^A$');
+    expect(await index.getDefinedNames(regExp, IndexNameKind.topLevel),
+        hasLength(1));
+    // remove the context - no
+    index.removeContext(context);
+    expect(
+        await index.getDefinedNames(regExp, IndexNameKind.topLevel), isEmpty);
+  }
+
   /**
    * Assert that the given list of [locations] has a [Location] corresponding
    * to the [element].
    */
   void _assertHasDefinedName(List<Location> locations, Element element) {
     String libraryUri = element.library.source.uri.toString();
     String unitUri = element.source.uri.toString();
     for (Location location in locations) {
       if (location.libraryUri == libraryUri &&
           location.unitUri == unitUri &&
@@ skipping 11 matching lines @@
     index.indexUnit(testUnit);
   }
 
   Source _indexUnit(String path, String code) {
     Source source = addSource(path, code);
     CompilationUnit unit = resolveLibraryUnit(source);
     index.indexUnit(unit);
     return source;
   }
 }