Prepare for decoupling analyzer ASTs from element model.

pkg/analysis_server/test/services/correction/assist_test.dart

Index: pkg/analysis_server/test/services/correction/assist_test.dart
diff --git a/pkg/analysis_server/test/services/correction/assist_test.dart b/pkg/analysis_server/test/services/correction/assist_test.dart
index a2abeee9b09daaec8baeb7ab63ce7cdf28baeb6b..6454cb2e7b9863480dd47033467e24a8a868ea60 100644
--- a/pkg/analysis_server/test/services/correction/assist_test.dart
+++ b/pkg/analysis_server/test/services/correction/assist_test.dart
@@ -10,6 +10,7 @@ import 'package:analysis_server/plugin/edit/assist/assist_core.dart';
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/plugin/server_plugin.dart';
 import 'package:analysis_server/src/services/correction/assist.dart';
+import 'package:analyzer/dart/ast/resolution_accessors.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:plugin/manager.dart';
@@ -64,8 +65,8 @@ class AssistProcessorTest extends AbstractSingleUnitTest {
    * Asserts that there is no [Assist] of the given [kind] at [offset].
    */
   assertNoAssist(AssistKind kind) async {
-    List<Assist> assists = await computeAssists(
-        plugin, context, testUnit.element.source, offset, length);
+    List<Assist> assists = await computeAssists(plugin, context,
+        elementForCompilationUnit(testUnit).source, offset, length);
     for (Assist assist in assists) {
       if (assist.kind == kind) {
         throw fail('Unexpected assist $kind in\n${assists.join('\n')}');
@@ -2683,8 +2684,8 @@ main(p) {
 
   test_invalidSelection() async {
     resolveTestUnit('');
-    List<Assist> assists =
-        await computeAssists(plugin, context, testUnit.element.source, -1, 0);
+    List<Assist> assists = await computeAssists(
+        plugin, context, elementForCompilationUnit(testUnit).source, -1, 0);
     expect(assists, isEmpty);
   }
 
@@ -4157,8 +4158,8 @@ main() {
    * Computes assists and verifies that there is an assist of the given kind.
    */
   Future<Assist> _assertHasAssist(AssistKind kind) async {
-    List<Assist> assists = await computeAssists(
-        plugin, context, testUnit.element.source, offset, length);
+    List<Assist> assists = await computeAssists(plugin, context,
+        elementForCompilationUnit(testUnit).source, offset, length);
     for (Assist assist in assists) {
       if (assist.kind == kind) {
         return assist;