Update failing tests (TBR)

pkg/analysis_server/test/src/utilities/change_builder_dart_test.dart

 // Copyright (c) 2015, 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 'dart:async';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:analysis_server/src/provisional/edit/utilities/change_builder_core.dart';
 import 'package:analysis_server/src/provisional/edit/utilities/change_builder_dart.dart';
 import 'package:analysis_server/src/utilities/change_builder_dart.dart';
@@ skipping 1123 matching lines @@
     CompilationUnit unit = (await driver.getResult(path))?.unit;
     FunctionDeclaration function = unit.declarations[0];
     FunctionBody body = function.functionExpression.body;
 
     DartChangeBuilderImpl builder = new DartChangeBuilderImpl(driver);
     await builder.addFileEdit(path, 1, (FileEditBuilder builder) {
       (builder as DartFileEditBuilder)
           .convertFunctionFromSyncToAsync(body, typeProvider);
     });
     List<SourceEdit> edits = getEdits(builder);
-    expect(edits, hasLength(2));
+    expect(edits, hasLength(3));
     expect(edits[0].replacement, equalsIgnoringWhitespace('async'));
-    expect(edits[1].replacement, equalsIgnoringWhitespace('Future<String>'));
+    expect(
+        edits[1].replacement, equalsIgnoringWhitespace("import 'dart:async';"));
+    expect(edits[2].replacement, equalsIgnoringWhitespace('Future<String>'));
   }
 
   test_createEditBuilder() async {
     String path = '/test.dart';
     addSource(path, 'library test;');
     int timeStamp = 65;
     DartChangeBuilderImpl builder = new DartChangeBuilderImpl(driver);
     await builder.addFileEdit(path, timeStamp, (FileEditBuilder builder) {
       int offset = 4;
       int length = 5;
@@ skipping 13 matching lines @@
 
     CompilationUnit unit = (await driver.getResult(path))?.unit;
     FunctionDeclaration function = unit.declarations[0];
     TypeAnnotation type = function.returnType;
 
     DartChangeBuilderImpl builder = new DartChangeBuilderImpl(driver);
     await builder.addFileEdit(path, 1, (FileEditBuilder builder) {
       (builder as DartFileEditBuilder)
           .replaceTypeWithFuture(type, typeProvider);
     });
-    SourceEdit edit = getEdit(builder);
-    expect(edit.replacement, equalsIgnoringWhitespace('Future<String>'));
+    List<SourceEdit> edits = getEdits(builder);
+    expect(edits, hasLength(2));
+    expect(
+        edits[0].replacement, equalsIgnoringWhitespace("import 'dart:async';"));
+    expect(edits[1].replacement, equalsIgnoringWhitespace('Future<String>'));
   }
 }
 
 @reflectiveTest
 class DartLinkedEditBuilderImplTest extends AbstractContextTest {
   @override
   bool get enableNewAnalysisDriver => true;
 
   test_addSuperTypesAsSuggestions() async {
     String path = '/test.dart';
     addSource(
         path,
         '''
 class A {}
 class B extends A {}
 class C extends B {}
 ''');
     CompilationUnit unit = (await driver.getResult(path))?.unit;
     ClassDeclaration classC = unit.declarations[2];
     DartLinkedEditBuilderImpl builder = new DartLinkedEditBuilderImpl(null);
     builder.addSuperTypesAsSuggestions(classC.element.type);
     List<LinkedEditSuggestion> suggestions = builder.suggestions;
     expect(suggestions, hasLength(4));
     expect(suggestions.map((s) => s.value),
         unorderedEquals(['Object', 'A', 'B', 'C']));
   }
 }