Improve Dart master index selectivity.

pkg/analysis_services/test/index/store/codec_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.services.src.index.store.codec;
 
 import 'package:analysis_services/index/index.dart';
 import 'package:analysis_services/src/index/store/codec.dart';
 import 'package:analysis_testing/mocks.dart';
 import 'package:analysis_testing/reflective_tests.dart';
@@ skipping 87 matching lines @@
     {
       int id = codec.encode(setter);
       expect(codec.decode(context, id), setter);
     }
     {
       int id = codec.encode(field);
       expect(codec.decode(context, id), field);
     }
   }
 
+  void test_encodeHash_notLocal() {
+    resolveTestUnit('''
+class A {
+  void mainA() {
+    int foo; // A
+  }
+  void mainB() {
+    int foo; // B
+    int bar;
+  }
+}
+''');
+    MethodElement mainA = findElement('mainA');
+    MethodElement mainB = findElement('mainB');
+    Element fooA = mainA.localVariables[0];
+    Element fooB = mainB.localVariables[0];
+    Element bar = mainB.localVariables[1];
+    int id_fooA = codec.encodeHash(fooA);
+    int id_fooB = codec.encodeHash(fooB);
+    int id_bar = codec.encodeHash(bar);
+    expect(id_fooA == id_fooB, isTrue);
+    expect(id_fooA == id_bar, isFalse);
+  }
+
   void test_localLocalVariable() {
     resolveTestUnit('''
 main() {
   {
     foo() {
       int bar; // A
     }
   }
   {
     foo() {
@@ skipping 88 matching lines @@
 class _StringCodecTest {
   StringCodec codec = new StringCodec();
 
   void test_all() {
     int idA = codec.encode('aaa');
     int idB = codec.encode('bbb');
     expect(codec.decode(idA), 'aaa');
     expect(codec.decode(idB), 'bbb');
   }
 }