diff --git a/pkg/analysis_server/lib/src/lsp/handlers/handler_completion_resolve.dart b/pkg/analysis_server/lib/src/lsp/handlers/handler_completion_resolve.dart
index c183d33..d5de4c1 100644
--- a/pkg/analysis_server/lib/src/lsp/handlers/handler_completion_resolve.dart
+++ b/pkg/analysis_server/lib/src/lsp/handlers/handler_completion_resolve.dart
@@ -11,6 +11,7 @@
 import 'package:analysis_server/src/lsp/handlers/handlers.dart';
 import 'package:analysis_server/src/lsp/lsp_analysis_server.dart';
 import 'package:analysis_server/src/lsp/mapping.dart';
+import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/dart/element/element.dart' as analyzer;
 import 'package:analyzer/src/util/comment.dart' as analyzer;
@@ -101,16 +102,17 @@
         }
 
         analyzer.LibraryElement requestedLibraryElement;
-        try {
-          requestedLibraryElement = await session.getLibraryByUri(
-            library.uriStr,
-          );
-        } on ArgumentError catch (e) {
-          return error(
-            ErrorCodes.InvalidParams,
-            'Invalid library URI: ${library.uriStr}',
-            '$e',
-          );
+        {
+          var result = await session.getLibraryByUri2(library.uriStr);
+          if (result is LibraryElementResult) {
+            requestedLibraryElement = result.element;
+          } else {
+            return error(
+              ErrorCodes.InvalidParams,
+              'Invalid library URI: ${library.uriStr}',
+              '${result.runtimeType}',
+            );
+          }
         }
 
         if (token.isCancellationRequested) {
diff --git a/pkg/analysis_server/test/analysis/get_errors_test.dart b/pkg/analysis_server/test/analysis/get_errors_test.dart
index 145a3a5..fe232a6 100644
--- a/pkg/analysis_server/test/analysis/get_errors_test.dart
+++ b/pkg/analysis_server/test/analysis/get_errors_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
@@ -128,7 +126,7 @@
     var request = _createGetErrorsRequest(file);
     var response = await serverChannel.sendRequest(request);
     expect(response.error, isNotNull);
-    expect(response.error.code, RequestErrorCode.GET_ERRORS_INVALID_FILE);
+    expect(response.error!.code, RequestErrorCode.GET_ERRORS_INVALID_FILE);
   }
 
   Request _createGetErrorsRequest(String file) {
diff --git a/pkg/analysis_server/test/analysis/get_hover_test.dart b/pkg/analysis_server/test/analysis/get_hover_test.dart
index d361d10..ec55a85 100644
--- a/pkg/analysis_server/test/analysis/get_hover_test.dart
+++ b/pkg/analysis_server/test/analysis/get_hover_test.dart
@@ -2,10 +2,7 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol_generated.dart';
-import 'package:meta/meta.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -45,12 +42,11 @@
 
 @reflectiveTest
 class AnalysisHoverTest extends AbstractAnalysisTest {
-  Future<HoverInformation> prepareHover(String search) {
-    var offset = findOffset(search);
-    return prepareHoverAt(offset);
+  Future<HoverInformation> prepareHover(String search) async {
+    return (await prepareHoverOrNull(search))!;
   }
 
-  Future<HoverInformation> prepareHoverAt(int offset) async {
+  Future<HoverInformation?> prepareHoverAt(int offset) async {
     await waitForTasksFinished();
     var request = AnalysisGetHoverParams(testFile, offset).toRequest('0');
     var response = await waitResponse(request);
@@ -59,6 +55,11 @@
     return hovers.isNotEmpty ? hovers.first : null;
   }
 
+  Future<HoverInformation?> prepareHoverOrNull(String search) {
+    var offset = findOffset(search);
+    return prepareHoverAt(offset);
+  }
+
   @override
   void setUp() {
     super.setUp();
@@ -662,7 +663,7 @@
   // nothing
 }
 ''');
-    var hover = await prepareHover('nothing');
+    var hover = await prepareHoverOrNull('nothing');
     expect(hover, isNull);
   }
 
@@ -896,10 +897,10 @@
 
   void _assertHover(
     HoverInformation hover, {
-    String containingLibraryPath,
-    String containingLibraryName,
-    @required String elementDescription,
-    @required String elementKind,
+    String? containingLibraryPath,
+    String? containingLibraryName,
+    required String elementDescription,
+    required String elementKind,
     bool isDeprecated = false,
   }) {
     containingLibraryName ??= 'bin/test.dart';
diff --git a/pkg/analysis_server/test/analysis/get_signature_test.dart b/pkg/analysis_server/test/analysis/get_signature_test.dart
index 5d4e202..37c6996 100644
--- a/pkg/analysis_server/test/analysis/get_signature_test.dart
+++ b/pkg/analysis_server/test/analysis/get_signature_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/src/protocol_server.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ -24,7 +22,7 @@
     return prepareRawSignatureAt(offset);
   }
 
-  Future<Response> prepareRawSignatureAt(int offset, {String file}) async {
+  Future<Response> prepareRawSignatureAt(int offset, {String? file}) async {
     await waitForTasksFinished();
     var request =
         AnalysisGetSignatureParams(file ?? testFile, offset).toRequest('0');
@@ -37,7 +35,7 @@
   }
 
   Future<AnalysisGetSignatureResult> prepareSignatureAt(int offset,
-      {String file}) async {
+      {String? file}) async {
     var response = await prepareRawSignatureAt(offset, file: file);
     return AnalysisGetSignatureResult.fromResponse(response);
   }
@@ -131,17 +129,15 @@
 }
 ''');
     var result = await prepareRawSignature('/*^*/');
-    expect(result.error, isNotNull);
-    expect(result.error.code,
-        equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
+    var error = result.error!;
+    expect(error.code, equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
   }
 
   Future<void> test_error_file_not_analyzed() async {
     var result = await prepareRawSignatureAt(0,
         file: convertPath('/not/in/project.dart'));
-    expect(result.error, isNotNull);
-    expect(
-        result.error.code, equals(RequestErrorCode.GET_SIGNATURE_INVALID_FILE));
+    var error = result.error!;
+    expect(error.code, equals(RequestErrorCode.GET_SIGNATURE_INVALID_FILE));
   }
 
   Future<void> test_error_function_unknown() async {
@@ -149,9 +145,8 @@
 someFunc(/*^*/);
 ''');
     var result = await prepareRawSignature('/*^*/');
-    expect(result.error, isNotNull);
-    expect(result.error.code,
-        equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
+    var error = result.error!;
+    expect(error.code, equals(RequestErrorCode.GET_SIGNATURE_UNKNOWN_FUNCTION));
   }
 
   Future<void> test_error_offset_invalid() async {
@@ -159,9 +154,8 @@
 a() {}
 ''');
     var result = await prepareRawSignatureAt(1000);
-    expect(result.error, isNotNull);
-    expect(result.error.code,
-        equals(RequestErrorCode.GET_SIGNATURE_INVALID_OFFSET));
+    var error = result.error!;
+    expect(error.code, equals(RequestErrorCode.GET_SIGNATURE_INVALID_OFFSET));
   }
 
   Future<void> test_function_expression() async {
diff --git a/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart b/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
index 55924d9..32081a6 100644
--- a/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_analysis_options_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
@@ -33,13 +31,13 @@
   print(y);
 }''';
 
-  List<AnalysisError> get errors => filesErrors[testFile];
+  List<AnalysisError> get errors => filesErrors[testFile]!;
 
-  List<AnalysisError> get optionsFileErrors => filesErrors[optionsFilePath];
+  List<AnalysisError> get optionsFileErrors => filesErrors[optionsFilePath]!;
 
   String get optionsFilePath => '$projectPath/analysis_options.yaml';
 
-  List<AnalysisError> get testFileErrors => filesErrors[testFile];
+  List<AnalysisError> get testFileErrors => filesErrors[testFile]!;
 
   void addOptionsFile(String contents) {
     newFile(optionsFilePath, content: contents);
diff --git a/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart b/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
index 9561c95..c7bcb7e 100644
--- a/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_analyzed_files_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -20,7 +18,7 @@
 
 @reflectiveTest
 class AnalysisNotificationAnalyzedFilesTest extends AbstractAnalysisTest {
-  List<String> analyzedFiles;
+  late List<String> analyzedFiles;
   bool analyzedFilesReceived = false;
 
   void assertHasFile(String filePath) {
diff --git a/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart b/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
index da4b925..972025f 100644
--- a/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -38,9 +36,9 @@
     ClosingLabel(79, 57, '<Widget>[]')
   ];
 
-  List<ClosingLabel> lastLabels;
+  List<ClosingLabel>? lastLabels;
 
-  Completer _labelsReceived;
+  late Completer _labelsReceived;
 
   @override
   void processNotification(Notification notification) {
diff --git a/pkg/analysis_server/test/analysis/notification_errors_test.dart b/pkg/analysis_server/test/analysis/notification_errors_test.dart
index 04dba84..c7c58d8 100644
--- a/pkg/analysis_server/test/analysis/notification_errors_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_errors_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -27,8 +25,8 @@
 
 @reflectiveTest
 class NotificationErrorsTest extends AbstractAnalysisTest {
-  Folder pedanticFolder;
-  Map<String, List<AnalysisError>> filesErrors = {};
+  late Folder pedanticFolder;
+  Map<String, List<AnalysisError>?> filesErrors = {};
 
   @override
   void processNotification(Notification notification) {
@@ -69,7 +67,7 @@
     //
     // Verify the error result.
     //
-    var errors = filesErrors[analysisOptionsFile];
+    var errors = filesErrors[analysisOptionsFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -90,7 +88,7 @@
     await pumpEventQueue();
 
     // Verify there's an error for the import.
-    var errors = filesErrors[analysisOptionsFile];
+    var errors = filesErrors[analysisOptionsFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -105,7 +103,7 @@
     // Ensure the errors disappear.
     await waitForTasksFinished();
     await pumpEventQueue();
-    errors = filesErrors[analysisOptionsFile];
+    errors = filesErrors[analysisOptionsFile]!;
     expect(errors, hasLength(0));
   }
 
@@ -132,7 +130,7 @@
     //
     // Verify the error result.
     //
-    var errors = filesErrors[manifestFile];
+    var errors = filesErrors[manifestFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -216,7 +214,7 @@
     //
     // Verify the error result.
     //
-    var errors = filesErrors[dataFile];
+    var errors = filesErrors[dataFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -309,7 +307,7 @@
 ''');
     await waitForTasksFinished();
     await pumpEventQueue(times: 5000);
-    var errors = filesErrors[testFile];
+    var errors = filesErrors[testFile]!;
     // Verify that we are generating only 1 error for the bad URI.
     // https://github.com/dart-lang/sdk/issues/23754
     expect(errors, hasLength(1));
@@ -336,7 +334,7 @@
 
     await waitForTasksFinished();
 
-    var testDriver = server.getAnalysisDriver(testFile);
+    var testDriver = server.getAnalysisDriver(testFile)!;
     var lints = testDriver.analysisOptions.lintRules;
 
     // Registry should only contain single lint rule.
@@ -345,7 +343,7 @@
     expect(lint.name, camelCaseTypesLintName);
 
     // Verify lint error result.
-    var errors = filesErrors[testFile];
+    var errors = filesErrors[testFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, join(projectPath, 'bin', 'test.dart'));
@@ -474,7 +472,7 @@
     addTestFile('library lib');
     await waitForTasksFinished();
     await pumpEventQueue(times: 5000);
-    var errors = filesErrors[testFile];
+    var errors = filesErrors[testFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, join(projectPath, 'bin', 'test.dart'));
@@ -499,7 +497,7 @@
     //
     // Verify the error result.
     //
-    var errors = filesErrors[pubspecFile];
+    var errors = filesErrors[pubspecFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -515,7 +513,7 @@
     await waitForTasksFinished();
     await pumpEventQueue();
 
-    errors = filesErrors[pubspecFile];
+    errors = filesErrors[pubspecFile]!;
     expect(errors, hasLength(0));
   }
 
@@ -544,7 +542,7 @@
     //
     // Verify the error result.
     //
-    var errors = filesErrors[pubspecFile];
+    var errors = filesErrors[pubspecFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.location.file, filePath);
@@ -563,7 +561,7 @@
     await waitForTasksFinished();
     await pumpEventQueue();
 
-    errors = filesErrors[pubspecFile];
+    errors = filesErrors[pubspecFile]!;
     expect(errors, hasLength(0));
   }
 
@@ -582,7 +580,7 @@
 ''');
     await waitForTasksFinished();
     await pumpEventQueue(times: 5000);
-    var errors = filesErrors[testFile];
+    var errors = filesErrors[testFile]!;
     expect(errors, hasLength(1));
     var error = errors[0];
     expect(error.severity, AnalysisErrorSeverity.WARNING);
diff --git a/pkg/analysis_server/test/analysis/notification_folding_test.dart b/pkg/analysis_server/test/analysis/notification_folding_test.dart
index d00446f..39612a6 100644
--- a/pkg/analysis_server/test/analysis/notification_folding_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_folding_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol_constants.dart';
@@ -34,9 +32,9 @@
     FoldingRegion(FoldingKind.DIRECTIVES, 6, 34)
   ];
 
-  List<FoldingRegion> lastRegions;
+  List<FoldingRegion>? lastRegions;
 
-  Completer _regionsReceived;
+  late Completer _regionsReceived;
 
   @override
   void processNotification(Notification notification) {
diff --git a/pkg/analysis_server/test/analysis/notification_highlights2_test.dart b/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
index 7bab497..301ef96 100644
--- a/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_highlights2_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -1244,7 +1242,7 @@
 }
 
 class HighlightsTestSupport extends AbstractAnalysisTest {
-  List<HighlightRegion> regions;
+  late List<HighlightRegion> regions;
 
   final Completer<void> _resultsAvailable = Completer();
 
diff --git a/pkg/analysis_server/test/analysis/notification_implemented_test.dart b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
index cc1b1c8..7e90f36 100644
--- a/pkg/analysis_server/test/analysis/notification_implemented_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -21,8 +19,8 @@
 
 @reflectiveTest
 class AnalysisNotificationImplementedTest extends AbstractAnalysisTest {
-  List<ImplementedClass> implementedClasses;
-  List<ImplementedMember> implementedMembers;
+  List<ImplementedClass>? implementedClasses;
+  List<ImplementedMember>? implementedMembers;
 
   /// Validates that there is an [ImplementedClass] at the offset of [search].
   ///
@@ -34,9 +32,9 @@
       length = findIdentifierLength(search);
     }
     if (implementedClasses == null) {
-      fail('No notification of impemented classes was received');
+      fail('No notification of implemented classes was received');
     }
-    for (var clazz in implementedClasses) {
+    for (var clazz in implementedClasses!) {
       if (clazz.offset == offset && clazz.length == length) {
         return;
       }
@@ -55,9 +53,9 @@
       length = findIdentifierLength(search);
     }
     if (implementedMembers == null) {
-      fail('No notification of impemented members was received');
+      fail('No notification of implemented members was received');
     }
-    for (var member in implementedMembers) {
+    for (var member in implementedMembers!) {
       if (member.offset == offset && member.length == length) {
         return;
       }
@@ -76,9 +74,9 @@
       length = findIdentifierLength(search);
     }
     if (implementedMembers == null) {
-      fail('No notification of impemented members was received');
+      fail('No notification of implemented members was received');
     }
-    for (var member in implementedMembers) {
+    for (var member in implementedMembers!) {
       if (member.offset == offset) {
         fail('Unexpected implemented member at $offset'
             ' in $implementedMembers');
diff --git a/pkg/analysis_server/test/analysis/notification_navigation_test.dart b/pkg/analysis_server/test/analysis/notification_navigation_test.dart
index c99d007..bc98cb2 100644
--- a/pkg/analysis_server/test/analysis/notification_navigation_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_navigation_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -22,14 +20,14 @@
 }
 
 class AbstractNavigationTest extends AbstractAnalysisTest {
-  List<NavigationRegion> regions;
-  List<NavigationTarget> targets;
-  List<String> targetFiles;
+  late List<NavigationRegion> regions;
+  late List<NavigationTarget> targets;
+  late List<String> targetFiles;
 
-  NavigationRegion testRegion;
-  List<int> testTargetIndexes;
-  List<NavigationTarget> testTargets;
-  NavigationTarget testTarget;
+  late NavigationRegion testRegion;
+  late List<int> testTargetIndexes;
+  late List<NavigationTarget> testTargets;
+  late NavigationTarget testTarget;
 
   /// Validates that there is a target in [testTargetIndexes] with [file],
   /// at [offset] and with the given [length].
diff --git a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
index bf46653..576456a 100644
--- a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -23,8 +21,8 @@
 
 @reflectiveTest
 class AnalysisNotificationOccurrencesTest extends AbstractAnalysisTest {
-  List<Occurrences> occurrencesList;
-  Occurrences testOccurrences;
+  late List<Occurrences> occurrencesList;
+  late Occurrences testOccurrences;
 
   final Completer<void> _resultsAvailable = Completer();
 
@@ -51,7 +49,7 @@
   /// Otherwise remembers this it into [testOccurrences].
   ///
   /// If [exists] is `false`, then fails if such [Occurrences] exists.
-  void findRegion(int offset, int length, [bool exists]) {
+  void findRegion(int offset, int length, [bool? exists]) {
     for (var occurrences in occurrencesList) {
       if (occurrences.length != length) {
         continue;
diff --git a/pkg/analysis_server/test/analysis/notification_outline_test.dart b/pkg/analysis_server/test/analysis/notification_outline_test.dart
index f372764..5488d67 100644
--- a/pkg/analysis_server/test/analysis/notification_outline_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_outline_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -23,12 +21,12 @@
 
 @reflectiveTest
 class AnalysisNotificationOutlineTest extends AbstractAnalysisTest {
-  FileKind fileKind;
-  String libraryName;
-  Outline outline;
+  late FileKind fileKind;
+  String? libraryName;
+  Outline? outline;
 
   final Completer<void> _outlineReceived = Completer();
-  Completer _highlightsReceived = Completer();
+  Completer? _highlightsReceived = Completer();
 
   Future prepareOutline() {
     addAnalysisSubscription(AnalysisService.OUTLINE, testFile);
@@ -71,7 +69,7 @@
     await waitForTasksFinished();
     expect(outline, isNull);
     await prepareOutline();
-    var unitOutline = outline;
+    var unitOutline = outline!;
     var outlines = unitOutline.children;
     expect(outlines, hasLength(2));
   }
@@ -128,11 +126,11 @@
     // This will pre-cache the analysis result for the file.
     setPriorityFiles([testFile]);
     addAnalysisSubscription(AnalysisService.HIGHLIGHTS, testFile);
-    await _highlightsReceived.future;
+    await _highlightsReceived!.future;
 
     // Now subscribe for outline notification, we must get it even though
     // the result which is used is pre-cached, and not a newly computed.
     await prepareOutline();
-    expect(outline.children, hasLength(2));
+    expect(outline!.children, hasLength(2));
   }
 }
diff --git a/pkg/analysis_server/test/analysis/notification_overrides_test.dart b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
index 14f5294..a3846b4 100644
--- a/pkg/analysis_server/test/analysis/notification_overrides_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_overrides_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -22,8 +20,8 @@
 
 @reflectiveTest
 class AnalysisNotificationOverridesTest extends AbstractAnalysisTest {
-  List<Override> overridesList;
-  Override overrideObject;
+  late List<Override> overridesList;
+  late Override overrideObject;
 
   final Completer<void> _resultsAvailable = Completer();
 
@@ -31,13 +29,14 @@
   /// offset of [search] in [override].
   void assertHasInterfaceMember(String search) {
     var offset = findOffset(search);
-    for (var member in overrideObject.interfaceMembers) {
-      if (member.element.location.offset == offset) {
+    var interfaceMembers = overrideObject.interfaceMembers!;
+    for (var member in interfaceMembers) {
+      if (member.element.location!.offset == offset) {
         return;
       }
     }
     fail('Expect to find an overridden interface members at $offset in '
-        '${overrideObject.interfaceMembers.join('\n')}');
+        '${interfaceMembers.join('\n')}');
   }
 
   /// Validates that there is an [Override] at the offset of [search].
@@ -57,7 +56,7 @@
   void assertHasSuperElement(String search) {
     var offset = findOffset(search);
     var member = overrideObject.superclassMember;
-    expect(member.element.location.offset, offset);
+    expect(member!.element.location!.offset, offset);
   }
 
   /// Asserts that there are no overridden members from interfaces.
@@ -88,7 +87,7 @@
   /// Otherwise remembers this it into [override].
   ///
   /// If [exists] is `false`, then fails if such [Override] exists.
-  void findOverride(int offset, int length, [bool exists]) {
+  void findOverride(int offset, int length, [bool? exists]) {
     for (var override in overridesList) {
       if (override.offset == offset && override.length == length) {
         if (exists == false) {
diff --git a/pkg/analysis_server/test/analysis/reanalyze_test.dart b/pkg/analysis_server/test/analysis/reanalyze_test.dart
index 934e6cc..358df55 100644
--- a/pkg/analysis_server/test/analysis/reanalyze_test.dart
+++ b/pkg/analysis_server/test/analysis/reanalyze_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
diff --git a/pkg/analysis_server/test/analysis/set_priority_files_test.dart b/pkg/analysis_server/test/analysis/set_priority_files_test.dart
index 8554189..0dc51e8 100644
--- a/pkg/analysis_server/test/analysis/set_priority_files_test.dart
+++ b/pkg/analysis_server/test/analysis/set_priority_files_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
@@ -139,8 +137,7 @@
     var response = await _setPriorityFile(testFile);
     expect(response, isResponseSuccess('0'));
     // verify
-    var params = pluginManager.analysisSetPriorityFilesParams;
-    expect(params, isNotNull);
+    var params = pluginManager.analysisSetPriorityFilesParams!;
     expect(params.files, <String>[testFile]);
   }
 
@@ -155,7 +152,7 @@
   }
 
   void _verifyPriorityFiles(String path) {
-    var driver = server.getAnalysisDriver(path);
+    var driver = server.getAnalysisDriver(path)!;
     var prioritySources = driver.priorityFiles;
     expect(prioritySources, [path]);
   }
diff --git a/pkg/analysis_server/test/analysis/update_content_test.dart b/pkg/analysis_server/test/analysis/update_content_test.dart
index 9051b35..3d6a4ec 100644
--- a/pkg/analysis_server/test/analysis/update_content_test.dart
+++ b/pkg/analysis_server/test/analysis/update_content_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -56,7 +54,7 @@
       fail('Expected an exception to be thrown');
     } on RequestFailure catch (e) {
       expect(e.response.id, id);
-      expect(e.response.error.code, RequestErrorCode.INVALID_OVERLAY_CHANGE);
+      expect(e.response.error!.code, RequestErrorCode.INVALID_OVERLAY_CHANGE);
     }
   }
 
@@ -162,8 +160,8 @@
 
     // exactly 2 contexts
     expect(server.driverMap, hasLength(2));
-    var driver1 = server.getAnalysisDriver(filePath1);
-    var driver2 = server.getAnalysisDriver(filePath2);
+    var driver1 = server.getAnalysisDriver(filePath1)!;
+    var driver2 = server.getAnalysisDriver(filePath2)!;
 
     // no sources
     expect(_getUserSources(driver1), isEmpty);
@@ -229,39 +227,38 @@
     // Add
     //
     handleSuccessfulRequest(AnalysisUpdateContentParams(
-            <String, dynamic>{filePath: AddContentOverlay(fileContent)})
+            <String, Object>{filePath: AddContentOverlay(fileContent)})
         .toRequest('0'));
-    var params = pluginManager.analysisUpdateContentParams;
-    expect(params, isNotNull);
+    var params = pluginManager.analysisUpdateContentParams!;
     var files = params.files;
     expect(files, hasLength(1));
     var overlay = files[filePath];
     expect(overlay, const TypeMatcher<AddContentOverlay>());
-    AddContentOverlay addOverlay = overlay;
+    var addOverlay = overlay as AddContentOverlay;
     expect(addOverlay.content, fileContent);
     //
     // Change
     //
     pluginManager.analysisUpdateContentParams = null;
-    handleSuccessfulRequest(AnalysisUpdateContentParams(<String, dynamic>{
+    handleSuccessfulRequest(AnalysisUpdateContentParams(<String, Object>{
       filePath: ChangeContentOverlay(
           <SourceEdit>[SourceEdit(8, 1, "'"), SourceEdit(18, 1, "'")])
     }).toRequest('1'));
-    params = pluginManager.analysisUpdateContentParams;
+    params = pluginManager.analysisUpdateContentParams!;
     expect(params, isNotNull);
     files = params.files;
     expect(files, hasLength(1));
     overlay = files[filePath];
     expect(overlay, const TypeMatcher<ChangeContentOverlay>());
-    ChangeContentOverlay changeOverlay = overlay;
+    var changeOverlay = overlay as ChangeContentOverlay;
     expect(changeOverlay.edits, hasLength(2));
     //
     // Remove
     //
     pluginManager.analysisUpdateContentParams = null;
     handleSuccessfulRequest(AnalysisUpdateContentParams(
-        <String, dynamic>{filePath: RemoveContentOverlay()}).toRequest('2'));
-    params = pluginManager.analysisUpdateContentParams;
+        <String, Object>{filePath: RemoveContentOverlay()}).toRequest('2'));
+    params = pluginManager.analysisUpdateContentParams!;
     expect(params, isNotNull);
     files = params.files;
     expect(files, hasLength(1));
@@ -269,13 +266,6 @@
     expect(overlay, const TypeMatcher<RemoveContentOverlay>());
   }
 
-//  CompilationUnit _getTestUnit() {
-//    ContextSourcePair pair = server.getContextSourcePair(testFile);
-//    AnalysisContext context = pair.context;
-//    Source source = pair.source;
-//    return context.getResolvedCompilationUnit2(source, source);
-//  }
-
   List<String> _getUserSources(AnalysisDriver driver) {
     var sources = <String>[];
     driver.addedFiles.forEach((path) {
diff --git a/pkg/analysis_server/test/analysis_abstract.dart b/pkg/analysis_server/test/analysis_abstract.dart
index ab75d6b..c55c715 100644
--- a/pkg/analysis_server/test/analysis_abstract.dart
+++ b/pkg/analysis_server/test/analysis_abstract.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
@@ -40,28 +38,29 @@
 
 /// An abstract base for all 'analysis' domain tests.
 class AbstractAnalysisTest with ResourceProviderMixin {
-  MockServerChannel serverChannel;
-  TestPluginManager pluginManager;
-  AnalysisServer server;
-  RequestHandler handler;
+  late MockServerChannel serverChannel;
+  late TestPluginManager pluginManager;
+  late AnalysisServer server;
+  late RequestHandler handler;
 
   final List<GeneralAnalysisService> generalServices =
       <GeneralAnalysisService>[];
   final Map<AnalysisService, List<String>> analysisSubscriptions = {};
 
-  String projectPath;
-  String testFolder;
-  String testFile;
-  String testCode;
+  late String projectPath;
+  late String testFolder;
+  late String testFile;
+  late String testCode;
 
   AbstractAnalysisTest();
 
-  AnalysisDomainHandler get analysisHandler => server.handlers
-      .singleWhere((handler) => handler is AnalysisDomainHandler);
+  AnalysisDomainHandler get analysisHandler =>
+      server.handlers.singleWhere((handler) => handler is AnalysisDomainHandler)
+          as AnalysisDomainHandler;
 
   AnalysisOptions get analysisOptions => testDiver.analysisOptions;
 
-  AnalysisDriver get testDiver => server.getAnalysisDriver(testFile);
+  AnalysisDriver get testDiver => server.getAnalysisDriver(testFile)!;
 
   void addAnalysisOptionsFile(String content) {
     newFile(
@@ -97,7 +96,7 @@
   }
 
   /// Create an analysis options file based on the given arguments.
-  void createAnalysisOptionsFile({List<String> experiments}) {
+  void createAnalysisOptionsFile({List<String>? experiments}) {
     var buffer = StringBuffer();
     if (experiments != null) {
       buffer.writeln('analyzer:');
@@ -128,14 +127,14 @@
   }
 
   /// Creates a project [projectPath].
-  void createProject({Map<String, String> packageRoots}) {
+  void createProject({Map<String, String>? packageRoots}) {
     newFolder(projectPath);
     setRoots(included: [projectPath], excluded: []);
   }
 
   void doAllDeclarationsTrackerWork() {
-    while (server.declarationsTracker.hasWork) {
-      server.declarationsTracker.doWork();
+    while (server.declarationsTracker!.hasWork) {
+      server.declarationsTracker!.doWork();
     }
   }
 
@@ -158,9 +157,9 @@
   }
 
   /// Validates that the given [request] is handled successfully.
-  Response handleSuccessfulRequest(Request request, {RequestHandler handler}) {
+  Response handleSuccessfulRequest(Request request, {RequestHandler? handler}) {
     handler ??= this.handler;
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     expect(response, isResponseSuccess(request.id));
     return response;
   }
@@ -190,8 +189,8 @@
   }
 
   void setRoots({
-    @required List<String> included,
-    @required List<String> excluded,
+    required List<String> included,
+    required List<String> excluded,
   }) {
     var includedConverted = included.map(convertPath).toList();
     var excludedConverted = excluded.map(convertPath).toList();
@@ -221,9 +220,6 @@
   @mustCallSuper
   void tearDown() {
     server.done();
-    handler = null;
-    server = null;
-    serverChannel = null;
   }
 
   /// Returns a [Future] that completes when the server's analysis is complete.
diff --git a/pkg/analysis_server/test/analysis_server_test.dart b/pkg/analysis_server/test/analysis_server_test.dart
index 50d0459..07cc2f4 100644
--- a/pkg/analysis_server/test/analysis_server_test.dart
+++ b/pkg/analysis_server/test/analysis_server_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -27,8 +25,8 @@
 
 @reflectiveTest
 class AnalysisServerTest with ResourceProviderMixin {
-  MockServerChannel channel;
-  AnalysisServer server;
+  late MockServerChannel channel;
+  late AnalysisServer server;
 
   /// Test that having multiple analysis contexts analyze the same file doesn't
   /// cause that file to receive duplicate notifications when it's modified.
@@ -116,8 +114,9 @@
     expect(notifications.any((Notification notification) {
       if (notification.event == SERVER_NOTIFICATION_STATUS) {
         var params = ServerStatusParams.fromNotification(notification);
-        if (params.analysis != null) {
-          return params.analysis.isAnalyzing;
+        var analysis = params.analysis;
+        if (analysis != null) {
+          return analysis.isAnalyzing;
         }
       }
       return false;
@@ -126,7 +125,7 @@
     // The last notification should indicate that analysis is complete.
     var notification = notifications[notifications.length - 1];
     var params = ServerStatusParams.fromNotification(notification);
-    expect(params.analysis.isAnalyzing, isFalse);
+    expect(params.analysis!.isAnalyzing, isFalse);
   }
 
   Future test_serverStatusNotifications_noFiles() async {
@@ -145,8 +144,9 @@
     expect(notifications.any((Notification notification) {
       if (notification.event == SERVER_NOTIFICATION_STATUS) {
         var params = ServerStatusParams.fromNotification(notification);
-        if (params.analysis != null) {
-          return params.analysis.isAnalyzing;
+        var analysis = params.analysis;
+        if (analysis != null) {
+          return analysis.isAnalyzing;
         }
       }
       return false;
@@ -155,7 +155,7 @@
     // The last notification should indicate that analysis is complete.
     var notification = notifications[notifications.length - 1];
     var params = ServerStatusParams.fromNotification(notification);
-    expect(params.analysis.isAnalyzing, isFalse);
+    expect(params.analysis!.isAnalyzing, isFalse);
   }
 
   Future<void>
@@ -221,7 +221,7 @@
 
 class EchoHandler implements RequestHandler {
   @override
-  Response handleRequest(Request request) {
+  Response? handleRequest(Request request) {
     if (request.method == 'echo') {
       return Response(request.id, result: {'echo': true});
     }
diff --git a/pkg/analysis_server/test/client/impl/abstract_client.dart b/pkg/analysis_server/test/client/impl/abstract_client.dart
index 44e67e3..ac1a33c 100644
--- a/pkg/analysis_server/test/client/impl/abstract_client.dart
+++ b/pkg/analysis_server/test/client/impl/abstract_client.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
     hide AnalysisOptions;
@@ -13,6 +11,7 @@
 import 'package:analysis_server/src/server/crash_reporting_attachments.dart';
 import 'package:analysis_server/src/utilities/mocks.dart';
 import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/generated/engine.dart';
@@ -26,7 +25,7 @@
 abstract class AbstractClient {
   final MockServerChannel serverChannel;
   final TestPluginManager pluginManager;
-  AnalysisServer server;
+  late AnalysisServer server;
 
   final List<GeneralAnalysisService> generalServices =
       <GeneralAnalysisService>[];
@@ -34,18 +33,18 @@
 
   final String projectPath;
   final String testFilePath;
-  String testCode;
+  late String testCode;
 
-  MockSdk sdk;
+  late MockSdk sdk;
 
   final AnalysisServerOptions serverOptions;
 
   AbstractClient({
-    @required this.projectPath,
-    @required this.testFilePath,
-    @required String sdkPath,
-    @required this.serverOptions,
-  })  : serverChannel = MockServerChannel(),
+    required this.projectPath,
+    required this.testFilePath,
+    required String sdkPath,
+    required this.serverOptions,
+  })   : serverChannel = MockServerChannel(),
         pluginManager = TestPluginManager() {
     server = createAnalysisServer(sdkPath);
     var notificationStream = serverChannel.notificationController.stream;
@@ -54,17 +53,18 @@
     });
   }
 
-  AnalysisDomainHandler get analysisHandler => server.handlers
-      .singleWhere((handler) => handler is AnalysisDomainHandler);
+  AnalysisDomainHandler get analysisHandler =>
+      server.handlers.singleWhere((handler) => handler is AnalysisDomainHandler)
+          as AnalysisDomainHandler;
 
   AnalysisOptions get analysisOptions => testDriver.analysisOptions;
 
   CompletionDomainHandler get completionHandler =>
       server.handlers.whereType<CompletionDomainHandler>().single;
 
-  ResourceProvider get resourceProvider;
+  MemoryResourceProvider get resourceProvider;
 
-  AnalysisDriver get testDriver => server.getAnalysisDriver(testFilePath);
+  AnalysisDriver get testDriver => server.getAnalysisDriver(testFilePath)!;
 
   void addAnalysisOptionsFile(String content) {
     newFile(
@@ -118,7 +118,7 @@
 
   /// Create a project at [projectPath].
   @mustCallSuper
-  void createProject({Map<String, String> packageRoots}) {
+  void createProject({Map<String, String>? packageRoots}) {
     newFolder(projectPath);
     var request = AnalysisSetAnalysisRootsParams([projectPath], [],
             packageRoots: packageRoots)
@@ -129,9 +129,9 @@
   void expect(actual, matcher, {String reason});
 
   /// Validate that the given [request] is handled successfully.
-  Response handleSuccessfulRequest(Request request, {RequestHandler handler}) {
+  Response handleSuccessfulRequest(Request request, {RequestHandler? handler}) {
     handler ??= analysisHandler;
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     expect(response, isResponseSuccess(request.id));
     return response;
   }
diff --git a/pkg/analysis_server/test/domain_completion_util.dart b/pkg/analysis_server/test/domain_completion_util.dart
index 1d2720a..80786c5 100644
--- a/pkg/analysis_server/test/domain_completion_util.dart
+++ b/pkg/analysis_server/test/domain_completion_util.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
@@ -17,17 +15,17 @@
 import 'constants.dart';
 
 class AbstractCompletionDomainTest extends AbstractAnalysisTest {
-  String completionId;
-  int completionOffset;
-  int replacementOffset;
-  int replacementLength;
+  late String completionId;
+  late int completionOffset;
+  late int replacementOffset;
+  late int replacementLength;
   Map<String, Completer<void>> receivedSuggestionsCompleters = {};
   List<CompletionSuggestion> suggestions = [];
   bool suggestionsDone = false;
   Map<String, List<CompletionSuggestion>> allSuggestions = {};
 
   @override
-  String addTestFile(String content, {int offset}) {
+  String addTestFile(String content, {int? offset}) {
     completionOffset = content.indexOf('^');
     if (offset != null) {
       expect(completionOffset, -1, reason: 'cannot supply offset and ^');
@@ -44,11 +42,11 @@
   void assertHasResult(CompletionSuggestionKind kind, String completion,
       {bool isDeprecated = false,
       bool isPotential = false,
-      int selectionOffset,
-      int replacementOffset,
-      int replacementLength,
-      ElementKind elementKind}) {
-    CompletionSuggestion cs;
+      int? selectionOffset,
+      int? replacementOffset,
+      int? replacementLength,
+      ElementKind? elementKind}) {
+    CompletionSuggestion? cs;
     suggestions.forEach((s) {
       if (elementKind != null && s.element?.kind != elementKind) {
         return;
@@ -71,16 +69,17 @@
 
       fail('expected $expectationText, but found\n $completions');
     }
-    expect(cs.kind, equals(kind));
-    expect(cs.selectionOffset, selectionOffset ?? completion.length);
-    expect(cs.selectionLength, equals(0));
-    expect(cs.replacementOffset, equals(replacementOffset));
-    expect(cs.replacementLength, equals(replacementLength));
-    expect(cs.isDeprecated, equals(isDeprecated));
-    expect(cs.isPotential, equals(isPotential));
+    var suggestion = cs!;
+    expect(suggestion.kind, equals(kind));
+    expect(suggestion.selectionOffset, selectionOffset ?? completion.length);
+    expect(suggestion.selectionLength, equals(0));
+    expect(suggestion.replacementOffset, equals(replacementOffset));
+    expect(suggestion.replacementLength, equals(replacementLength));
+    expect(suggestion.isDeprecated, equals(isDeprecated));
+    expect(suggestion.isPotential, equals(isPotential));
   }
 
-  void assertNoResult(String completion, {ElementKind elementKind}) {
+  void assertNoResult(String completion, {ElementKind? elementKind}) {
     if (suggestions.any((cs) =>
         cs.completion == completion &&
         (elementKind == null || cs.element?.kind == elementKind))) {
diff --git a/pkg/analysis_server/test/domain_diagnostic_test.dart b/pkg/analysis_server/test/domain_diagnostic_test.dart
index 4f6860e..03f2c16 100644
--- a/pkg/analysis_server/test/domain_diagnostic_test.dart
+++ b/pkg/analysis_server/test/domain_diagnostic_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/domain_diagnostic.dart';
 import 'package:test/test.dart';
@@ -35,7 +33,7 @@
     await server.onAnalysisComplete;
 
     var request = DiagnosticGetDiagnosticsParams().toRequest('0');
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     var result = DiagnosticGetDiagnosticsResult.fromResponse(response);
 
     expect(result.contexts, hasLength(1));
@@ -51,7 +49,7 @@
 
   Future<void> test_getDiagnostics_noRoot() async {
     var request = DiagnosticGetDiagnosticsParams().toRequest('0');
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     var result = DiagnosticGetDiagnosticsResult.fromResponse(response);
     expect(result.contexts, isEmpty);
   }
diff --git a/pkg/analysis_server/test/domain_edit_dartfix_test.dart b/pkg/analysis_server/test/domain_edit_dartfix_test.dart
index a3b114c..fa53b77 100644
--- a/pkg/analysis_server/test/domain_edit_dartfix_test.dart
+++ b/pkg/analysis_server/test/domain_edit_dartfix_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/edit/edit_dartfix.dart';
@@ -39,18 +37,19 @@
   }
 
   void expectSuggestion(DartFixSuggestion suggestion, String partialText,
-      [int offset, int length]) {
+      [int? offset, int? length]) {
     expect(suggestion.description, contains(partialText));
     if (offset == null) {
       expect(suggestion.location, isNull);
     } else {
-      expect(suggestion.location.offset, offset);
-      expect(suggestion.location.length, length);
+      var location = suggestion.location!;
+      expect(location.offset, offset);
+      expect(location.length, length);
     }
   }
 
   Future<EditDartfixResult> performFix(
-      {List<String> includedFixes, bool pedantic}) async {
+      {List<String>? includedFixes, bool? pedantic}) async {
     var response =
         await performFixRaw(includedFixes: includedFixes, pedantic: pedantic);
     expect(response.error, isNull);
@@ -58,9 +57,9 @@
   }
 
   Future<Response> performFixRaw(
-      {List<String> includedFixes,
-      List<String> excludedFixes,
-      bool pedantic}) async {
+      {List<String>? includedFixes,
+      List<String>? excludedFixes,
+      bool? pedantic}) async {
     final id = nextRequestId;
     final params = EditDartfixParams([projectPath]);
     params.includedFixes = includedFixes;
diff --git a/pkg/analysis_server/test/domain_execution_test.dart b/pkg/analysis_server/test/domain_execution_test.dart
index ad5fb97..107cab5 100644
--- a/pkg/analysis_server/test/domain_execution_test.dart
+++ b/pkg/analysis_server/test/domain_execution_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/domain_execution.dart';
@@ -25,8 +23,8 @@
   });
   group('ExecutionDomainHandler', () {
     var provider = MemoryResourceProvider();
-    AnalysisServer server;
-    ExecutionDomainHandler handler;
+    late AnalysisServer server;
+    late ExecutionDomainHandler handler;
 
     setUp(() {
       server = AnalysisServer(
@@ -42,13 +40,13 @@
     group('createContext/deleteContext', () {
       test('create/delete multiple contexts', () {
         var request = ExecutionCreateContextParams('/a/b.dart').toRequest('0');
-        var response = handler.handleRequest(request);
+        var response = handler.handleRequest(request)!;
         expect(response, isResponseSuccess('0'));
         var result = ExecutionCreateContextResult.fromResponse(response);
         var id0 = result.id;
 
         request = ExecutionCreateContextParams('/c/d.dart').toRequest('1');
-        response = handler.handleRequest(request);
+        response = handler.handleRequest(request)!;
         expect(response, isResponseSuccess('1'));
         result = ExecutionCreateContextResult.fromResponse(response);
         var id1 = result.id;
@@ -56,11 +54,11 @@
         expect(id0 == id1, isFalse);
 
         request = ExecutionDeleteContextParams(id0).toRequest('2');
-        response = handler.handleRequest(request);
+        response = handler.handleRequest(request)!;
         expect(response, isResponseSuccess('2'));
 
         request = ExecutionDeleteContextParams(id1).toRequest('3');
-        response = handler.handleRequest(request);
+        response = handler.handleRequest(request)!;
         expect(response, isResponseSuccess('3'));
       });
 
@@ -161,7 +159,7 @@
 
 @reflectiveTest
 class ExecutionDomainTest extends AbstractAnalysisTest {
-  String contextId;
+  late String contextId;
 
   @override
   void setUp() {
@@ -239,7 +237,7 @@
 
   void _createExecutionContext(String path) {
     var request = ExecutionCreateContextParams(path).toRequest('0');
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     expect(response, isResponseSuccess('0'));
     var result = ExecutionCreateContextResult.fromResponse(response);
     contextId = result.id;
@@ -251,10 +249,10 @@
     expect(response, isResponseSuccess('1'));
   }
 
-  ExecutionMapUriResult _mapUri({String file, String uri}) {
+  ExecutionMapUriResult _mapUri({String? file, String? uri}) {
     var request =
         ExecutionMapUriParams(contextId, file: file, uri: uri).toRequest('2');
-    var response = handler.handleRequest(request);
+    var response = handler.handleRequest(request)!;
     expect(response, isResponseSuccess('2'));
     return ExecutionMapUriResult.fromResponse(response);
   }
diff --git a/pkg/analysis_server/test/domain_server_test.dart b/pkg/analysis_server/test/domain_server_test.dart
index 9af7c95..2202712 100644
--- a/pkg/analysis_server/test/domain_server_test.dart
+++ b/pkg/analysis_server/test/domain_server_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -20,9 +18,9 @@
 import 'mocks.dart';
 
 void main() {
-  AnalysisServer server;
-  ServerDomainHandler handler;
-  MockServerChannel serverChannel;
+  late AnalysisServer server;
+  late ServerDomainHandler handler;
+  late MockServerChannel serverChannel;
 
   setUp(() {
     serverChannel = MockServerChannel();
@@ -40,7 +38,7 @@
   group('ServerDomainHandler', () {
     test('getVersion', () {
       var request = ServerGetVersionParams().toRequest('0');
-      var response = handler.handleRequest(request);
+      var response = handler.handleRequest(request)!;
       expect(
           response.toJson(),
           equals({
diff --git a/pkg/analysis_server/test/edit/fixes_test.dart b/pkg/analysis_server/test/edit/fixes_test.dart
index d037309..1a397f2 100644
--- a/pkg/analysis_server/test/edit/fixes_test.dart
+++ b/pkg/analysis_server/test/edit/fixes_test.dart
@@ -2,11 +2,10 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/edit/edit_domain.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
+import 'package:analyzer/instrumentation/service.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart' as plugin;
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/protocol/protocol_generated.dart' as plugin;
@@ -15,6 +14,7 @@
 
 import '../analysis_abstract.dart';
 import '../mocks.dart';
+import '../src/plugin/plugin_manager_test.dart';
 
 void main() {
   defineReflectiveSuite(() {
@@ -68,7 +68,8 @@
   }
 
   Future<void> test_fromPlugins() async {
-    PluginInfo info = DiscoveredPluginInfo('a', 'b', 'c', null, null);
+    PluginInfo info = DiscoveredPluginInfo('a', 'b', 'c',
+        TestNotificationManager(), InstrumentationService.NULL_SERVICE);
     var fixes = plugin.AnalysisErrorFixes(AnalysisError(
         AnalysisErrorSeverity.ERROR,
         AnalysisErrorType.HINT,
diff --git a/pkg/analysis_server/test/edit/postfix_completion_test.dart b/pkg/analysis_server/test/edit/postfix_completion_test.dart
index 7cbe83f..e58ee6c 100644
--- a/pkg/analysis_server/test/edit/postfix_completion_test.dart
+++ b/pkg/analysis_server/test/edit/postfix_completion_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/edit/edit_domain.dart';
@@ -22,7 +20,7 @@
 
 @reflectiveTest
 class PostfixCompletionTest extends AbstractAnalysisTest {
-  SourceChange change;
+  late SourceChange change;
 
   @override
   void setUp() {
@@ -69,7 +67,7 @@
     );
   }
 
-  void _assertHasChange(String message, String expectedCode, [Function cmp]) {
+  void _assertHasChange(String message, String expectedCode, [Function? cmp]) {
     if (change.message == message) {
       if (change.edits.isNotEmpty) {
         var resultCode =
@@ -77,12 +75,12 @@
         expect(resultCode, expectedCode.replaceAll('/*caret*/', ''));
         if (cmp != null) {
           int offset = cmp(resultCode);
-          expect(change.selection.offset, offset);
+          expect(change.selection!.offset, offset);
         }
       } else {
         if (cmp != null) {
           int offset = cmp(testCode);
-          expect(change.selection.offset, offset);
+          expect(change.selection!.offset, offset);
         }
       }
       return;
diff --git a/pkg/analysis_server/test/search/abstract_search_domain.dart b/pkg/analysis_server/test/search/abstract_search_domain.dart
index 50021f6..f6e20ee 100644
--- a/pkg/analysis_server/test/search/abstract_search_domain.dart
+++ b/pkg/analysis_server/test/search/abstract_search_domain.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
@@ -15,17 +13,17 @@
 
 class AbstractSearchDomainTest extends AbstractAnalysisTest {
   final Map<String, _ResultSet> resultSets = {};
-  String searchId;
+  late String searchId;
   List<SearchResult> results = <SearchResult>[];
-  SearchResult result;
+  late SearchResult result;
 
-  void assertHasResult(SearchResultKind kind, String search, [int length]) {
+  void assertHasResult(SearchResultKind kind, String search, [int? length]) {
     var offset = findOffset(search);
     length ??= findIdentifierLength(search);
     findResult(kind, testFile, offset, length, true);
   }
 
-  void assertNoResult(SearchResultKind kind, String search, [int length]) {
+  void assertNoResult(SearchResultKind kind, String search, [int? length]) {
     var offset = findOffset(search);
     length ??= findIdentifierLength(search);
     findResult(kind, testFile, offset, length, false);
diff --git a/pkg/analysis_server/test/search/type_hierarchy_test.dart b/pkg/analysis_server/test/search/type_hierarchy_test.dart
index 4b11bba..b257f54 100644
--- a/pkg/analysis_server/test/search/type_hierarchy_test.dart
+++ b/pkg/analysis_server/test/search/type_hierarchy_test.dart
@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.9
-
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/search/search_domain.dart';
@@ -36,7 +34,7 @@
 main() {
 }
 ''');
-    var items = await _getTypeHierarchy('main() {');
+    var items = await _getTypeHierarchyOrNull('main() {');
     expect(items, isNull);
   }
 
@@ -46,7 +44,7 @@
   /* target */
 }
 ''');
-    var items = await _getTypeHierarchy('/* target */');
+    var items = await _getTypeHierarchyOrNull('/* target */');
     expect(items, isNull);
   }
 
@@ -95,7 +93,7 @@
 ''');
     var items = await _getTypeHierarchy('B extends');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemA.displayName, 'A<int>');
@@ -507,12 +505,10 @@
     var items = await _getTypeHierarchy('test = 1;');
     var itemA = items.firstWhere((e) => e.classElement.name == 'A');
     var itemB = items.firstWhere((e) => e.classElement.name == 'B');
-    var memberA = itemA.memberElement;
-    var memberB = itemB.memberElement;
-    expect(memberA, isNotNull);
-    expect(memberB, isNotNull);
-    expect(memberA.location.offset, findOffset('test = 1;'));
-    expect(memberB.location.offset, findOffset('test => 2;'));
+    var memberA = itemA.memberElement!;
+    var memberB = itemB.memberElement!;
+    expect(memberA.location!.offset, findOffset('test = 1;'));
+    expect(memberB.location!.offset, findOffset('test => 2;'));
   }
 
   Future<void> test_fromField_toMixinSetter() async {
@@ -528,12 +524,10 @@
     var items = await _getTypeHierarchy('test = 1;');
     var itemA = items.firstWhere((e) => e.classElement.name == 'A');
     var itemB = items.firstWhere((e) => e.classElement.name == 'B');
-    var memberA = itemA.memberElement;
-    var memberB = itemB.memberElement;
-    expect(memberA, isNotNull);
-    expect(memberB, isNotNull);
-    expect(memberA.location.offset, findOffset('test = 1;'));
-    expect(memberB.location.offset, findOffset('test(m) {}'));
+    var memberA = itemA.memberElement!;
+    var memberB = itemB.memberElement!;
+    expect(memberA.location!.offset, findOffset('test = 1;'));
+    expect(memberB.location!.offset, findOffset('test(m) {}'));
   }
 
   Future<void> test_member_fromField_toField() async {
@@ -547,11 +541,11 @@
 ''');
     var items = await _getTypeHierarchy('test = 2;');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
-    expect(itemA.memberElement.location.offset, findOffset('test = 1;'));
-    expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
+    expect(itemA.memberElement!.location!.offset, findOffset('test = 1;'));
+    expect(itemB.memberElement!.location!.offset, findOffset('test = 2;'));
   }
 
   Future<void> test_member_fromField_toGetter() async {
@@ -565,11 +559,11 @@
 ''');
     var items = await _getTypeHierarchy('test = 2;');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
-    expect(itemA.memberElement.location.offset, findOffset('test => 1'));
-    expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
+    expect(itemA.memberElement!.location!.offset, findOffset('test => 1'));
+    expect(itemB.memberElement!.location!.offset, findOffset('test = 2;'));
   }
 
   Future<void> test_member_fromField_toSetter() async {
@@ -583,11 +577,11 @@
 ''');
     var items = await _getTypeHierarchy('test = 2;');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
-    expect(itemA.memberElement.location.offset, findOffset('test(a) {}'));
-    expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
+    expect(itemA.memberElement!.location!.offset, findOffset('test(a) {}'));
+    expect(itemB.memberElement!.location!.offset, findOffset('test = 2;'));
   }
 
   Future<void> test_member_fromFinalField_toGetter() async {
@@ -601,11 +595,11 @@
 ''');
     var items = await _getTypeHierarchy('test = 2;');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
-    expect(itemA.memberElement.location.offset, findOffset('test => 1;'));
-    expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
+    expect(itemA.memberElement!.location!.offset, findOffset('test => 1;'));
+    expect(itemB.memberElement!.location!.offset, findOffset('test = 2;'));
   }
 
   Future<void> test_member_fromFinalField_toSetter() async {
@@ -619,11 +613,11 @@
 ''');
     var items = await _getTypeHierarchy('test = 2;');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemA.memberElement, isNull);
-    expect(itemB.memberElement.location.offset, findOffset('test = 2;'));
+    expect(itemB.memberElement!.location!.offset, findOffset('test = 2;'));
   }
 
   Future<void> test_member_getter() async {
@@ -642,19 +636,19 @@
 ''');
     var items = await _getTypeHierarchy('test => null; // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     var itemD = items[itemC.subclasses[0]];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemC.classElement.name, 'C');
     expect(itemD.classElement.name, 'D');
-    expect(itemA.memberElement.location.offset,
+    expect(itemA.memberElement!.location!.offset,
         findOffset('test => null; // in A'));
-    expect(itemB.memberElement.location.offset,
+    expect(itemB.memberElement!.location!.offset,
         findOffset('test => null; // in B'));
     expect(itemC.memberElement, isNull);
-    expect(itemD.memberElement.location.offset,
+    expect(itemD.memberElement!.location!.offset,
         findOffset('test => null; // in D'));
   }
 
@@ -674,7 +668,7 @@
 ''');
     var items = await _getTypeHierarchy('test() {} // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     var itemD = items[itemC.subclasses[0]];
     expect(itemA.classElement.name, 'A');
@@ -682,12 +676,12 @@
     expect(itemC.classElement.name, 'C');
     expect(itemD.classElement.name, 'D');
     expect(
-        itemA.memberElement.location.offset, findOffset('test() {} // in A'));
+        itemA.memberElement!.location!.offset, findOffset('test() {} // in A'));
     expect(
-        itemB.memberElement.location.offset, findOffset('test() {} // in B'));
+        itemB.memberElement!.location!.offset, findOffset('test() {} // in B'));
     expect(itemC.memberElement, isNull);
     expect(
-        itemD.memberElement.location.offset, findOffset('test() {} // in D'));
+        itemD.memberElement!.location!.offset, findOffset('test() {} // in D'));
   }
 
   Future<void> test_member_method_private_differentLib() async {
@@ -711,7 +705,7 @@
 ''');
     var items = await _getTypeHierarchy('_m() {} // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     var itemD = items[itemC.subclasses[0]];
     expect(itemB.classElement.name, 'B');
@@ -738,14 +732,17 @@
 ''');
     var items = await _getTypeHierarchy('_m() {} // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemC.classElement.name, 'C');
-    expect(itemA.memberElement.location.offset, findOffset('_m() {} // in A'));
-    expect(itemB.memberElement.location.offset, findOffset('_m() {} // in B'));
-    expect(itemC.memberElement.location.offset, findOffset('_m() {} // in C'));
+    expect(
+        itemA.memberElement!.location!.offset, findOffset('_m() {} // in A'));
+    expect(
+        itemB.memberElement!.location!.offset, findOffset('_m() {} // in B'));
+    expect(
+        itemC.memberElement!.location!.offset, findOffset('_m() {} // in C'));
   }
 
   Future<void> test_member_ofMixin2_method() async {
@@ -781,9 +778,8 @@
     }
     // D2 mixes-in M2 last, which overrides
     {
-      var member2 = item2.memberElement;
-      expect(member2, isNotNull);
-      expect(member2.location.offset, findOffset('test() {} // in M2'));
+      var member2 = item2.memberElement!;
+      expect(member2.location!.offset, findOffset('test() {} // in M2'));
     }
     // D3 mixes-in M1 last and does not override itself
     {
@@ -792,8 +788,8 @@
     }
     // D4 mixes-in M1 last, but it also overrides
     {
-      var member4 = item4.memberElement;
-      expect(member4.location.offset, findOffset('test() {} // in D4'));
+      var member4 = item4.memberElement!;
+      expect(member4.location!.offset, findOffset('test() {} // in D4'));
     }
   }
 
@@ -814,15 +810,13 @@
     var itemBase = items.firstWhere((e) => e.classElement.name == 'Base');
     var item1 = items.firstWhere((e) => e.classElement.name == 'Derived1');
     var item2 = items.firstWhere((e) => e.classElement.name == 'Derived2');
-    var memberBase = itemBase.memberElement;
-    var member1 = item1.memberElement;
-    var member2 = item2.memberElement;
-    expect(memberBase, isNotNull);
-    expect(member1, isNotNull);
-    expect(member2, isNotNull);
-    expect(memberBase.location.offset, findOffset('test; // in Base'));
-    expect(member1.location.offset, findOffset('test => null; // in Mixin'));
-    expect(member2.location.offset, findOffset('test => null; // in Derived2'));
+    var memberBase = itemBase.memberElement!;
+    var member1 = item1.memberElement!;
+    var member2 = item2.memberElement!;
+    expect(memberBase.location!.offset, findOffset('test; // in Base'));
+    expect(member1.location!.offset, findOffset('test => null; // in Mixin'));
+    expect(
+        member2.location!.offset, findOffset('test => null; // in Derived2'));
   }
 
   Future<void> test_member_ofMixin_method() async {
@@ -842,15 +836,12 @@
     var itemBase = items.firstWhere((e) => e.classElement.name == 'Base');
     var item1 = items.firstWhere((e) => e.classElement.name == 'Derived1');
     var item2 = items.firstWhere((e) => e.classElement.name == 'Derived2');
-    var memberBase = itemBase.memberElement;
-    var member1 = item1.memberElement;
-    var member2 = item2.memberElement;
-    expect(memberBase, isNotNull);
-    expect(member1, isNotNull);
-    expect(member2, isNotNull);
-    expect(memberBase.location.offset, findOffset('test(); // in Base'));
-    expect(member1.location.offset, findOffset('test() {} // in Mixin'));
-    expect(member2.location.offset, findOffset('test() {} // in Derived2'));
+    var memberBase = itemBase.memberElement!;
+    var member1 = item1.memberElement!;
+    var member2 = item2.memberElement!;
+    expect(memberBase.location!.offset, findOffset('test(); // in Base'));
+    expect(member1.location!.offset, findOffset('test() {} // in Mixin'));
+    expect(member2.location!.offset, findOffset('test() {} // in Derived2'));
   }
 
   Future<void> test_member_ofMixin_setter() async {
@@ -870,15 +861,12 @@
     var itemBase = items.firstWhere((e) => e.classElement.name == 'Base');
     var item1 = items.firstWhere((e) => e.classElement.name == 'Derived1');
     var item2 = items.firstWhere((e) => e.classElement.name == 'Derived2');
-    var memberBase = itemBase.memberElement;
-    var member1 = item1.memberElement;
-    var member2 = item2.memberElement;
-    expect(memberBase, isNotNull);
-    expect(member1, isNotNull);
-    expect(member2, isNotNull);
-    expect(memberBase.location.offset, findOffset('test(x); // in Base'));
-    expect(member1.location.offset, findOffset('test(x) {} // in Mixin'));
-    expect(member2.location.offset, findOffset('test(x) {} // in Derived2'));
+    var memberBase = itemBase.memberElement!;
+    var member1 = item1.memberElement!;
+    var member2 = item2.memberElement!;
+    expect(memberBase.location!.offset, findOffset('test(x); // in Base'));
+    expect(member1.location!.offset, findOffset('test(x) {} // in Mixin'));
+    expect(member2.location!.offset, findOffset('test(x) {} // in Derived2'));
   }
 
   Future<void> test_member_ofSuperclassConstraint_getter() async {
@@ -954,19 +942,19 @@
 ''');
     var items = await _getTypeHierarchy('==(x) => null; // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     var itemD = items[itemC.subclasses[0]];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemC.classElement.name, 'C');
     expect(itemD.classElement.name, 'D');
-    expect(itemA.memberElement.location.offset,
+    expect(itemA.memberElement!.location!.offset,
         findOffset('==(x) => null; // in A'));
-    expect(itemB.memberElement.location.offset,
+    expect(itemB.memberElement!.location!.offset,
         findOffset('==(x) => null; // in B'));
     expect(itemC.memberElement, isNull);
-    expect(itemD.memberElement.location.offset,
+    expect(itemD.memberElement!.location!.offset,
         findOffset('==(x) => null; // in D'));
   }
 
@@ -986,20 +974,20 @@
 ''');
     var items = await _getTypeHierarchy('test(x) {} // in B');
     var itemB = items[0];
-    var itemA = items[itemB.superclass];
+    var itemA = items[itemB.superclass!];
     var itemC = items[itemB.subclasses[0]];
     var itemD = items[itemC.subclasses[0]];
     expect(itemA.classElement.name, 'A');
     expect(itemB.classElement.name, 'B');
     expect(itemC.classElement.name, 'C');
     expect(itemD.classElement.name, 'D');
-    expect(
-        itemA.memberElement.location.offset, findOffset('test(x) {} // in A'));
-    expect(
-        itemB.memberElement.location.offset, findOffset('test(x) {} // in B'));
+    expect(itemA.memberElement!.location!.offset,
+        findOffset('test(x) {} // in A'));
+    expect(itemB.memberElement!.location!.offset,
+        findOffset('test(x) {} // in B'));
     expect(itemC.memberElement, isNull);
-    expect(
-        itemD.memberElement.location.offset, findOffset('test(x) {} // in D'));
+    expect(itemD.memberElement!.location!.offset,
+        findOffset('test(x) {} // in D'));
   }
 
   Future<void> test_superOnly() async {
@@ -1073,17 +1061,22 @@
   }
 
   void _assertMember(TypeHierarchyItem item, String search) {
-    expect(item.memberElement.location.offset, findOffset(search));
+    expect(item.memberElement!.location!.offset, findOffset(search));
   }
 
-  Request _createGetTypeHierarchyRequest(String search, {bool superOnly}) {
+  Request _createGetTypeHierarchyRequest(String search, {bool? superOnly}) {
     return SearchGetTypeHierarchyParams(testFile, findOffset(search),
             superOnly: superOnly)
         .toRequest(requestId);
   }
 
   Future<List<TypeHierarchyItem>> _getTypeHierarchy(String search,
-      {bool superOnly}) async {
+      {bool? superOnly}) async {
+    return (await _getTypeHierarchyOrNull(search, superOnly: superOnly))!;
+  }
+
+  Future<List<TypeHierarchyItem>?> _getTypeHierarchyOrNull(String search,
+      {bool? superOnly}) async {
     await waitForTasksFinished();
     var request = _createGetTypeHierarchyRequest(search, superOnly: superOnly);
     var response = await serverChannel.sendRequest(request);
diff --git a/pkg/analysis_server/test/services/search/search_engine_test.dart b/pkg/analysis_server/test/services/search/search_engine_test.dart
index a352332..99aa552 100644
--- a/pkg/analysis_server/test/services/search/search_engine_test.dart
+++ b/pkg/analysis_server/test/services/search/search_engine_test.dart
@@ -328,8 +328,9 @@
 int t;
 ''').path;
 
-    var coreLib = await driverFor(testFilePath).getLibraryByUri('dart:core');
-    var intElement = coreLib.getType('int')!;
+    var coreLibResult = await driverFor(testFilePath)
+        .getLibraryByUri2('dart:core') as LibraryElementResult;
+    var intElement = coreLibResult.element.getType('int')!;
 
     var matches = await searchEngine.searchReferences(intElement);
 
diff --git a/pkg/analyzer/CHANGELOG.md b/pkg/analyzer/CHANGELOG.md
index bfe3d95..406ded7 100644
--- a/pkg/analyzer/CHANGELOG.md
+++ b/pkg/analyzer/CHANGELOG.md
@@ -7,6 +7,8 @@
   Use `AnalysisSession.getResolvedLibrary2()` instead.
 * Deprecated `AnalysisSession.getResolvedLibraryByElement()`.
   Use `AnalysisSession.getResolvedLibraryByElement2()` instead.
+* Deprecated `AnalysisSession.getLibraryByUri()`.
+  Use `AnalysisSession.getLibraryByUri2()` instead.
 
 ## 1.4.0
 * Deprecated `TypeProvider.nonSubtypableClasses`.
diff --git a/pkg/analyzer/lib/dart/analysis/results.dart b/pkg/analyzer/lib/dart/analysis/results.dart
index 3c6107a..e60f786 100644
--- a/pkg/analyzer/lib/dart/analysis/results.dart
+++ b/pkg/analyzer/lib/dart/analysis/results.dart
@@ -46,7 +46,10 @@
 ///
 /// Clients may not extend, implement or mix-in this class.
 class CannotResolveUriResult
-    implements InvalidResult, SomeResolvedLibraryResult {}
+    implements
+        InvalidResult,
+        SomeLibraryElementResult,
+        SomeResolvedLibraryResult {}
 
 /// The declaration of an [Element].
 abstract class ElementDeclarationResult {
@@ -103,6 +106,14 @@
 /// Clients may not extend, implement or mix-in this class.
 abstract class InvalidResult {}
 
+/// The result of building the element model for a library.
+///
+/// Clients may not extend, implement or mix-in this class.
+abstract class LibraryElementResult implements SomeLibraryElementResult {
+  /// The element of the library.
+  LibraryElement get element;
+}
+
 /// The type of [InvalidResult] returned when the given element was not
 /// created by the requested session.
 ///
@@ -115,7 +126,10 @@
 ///
 /// Clients may not extend, implement or mix-in this class.
 class NotLibraryButPartResult
-    implements InvalidResult, SomeResolvedLibraryResult {}
+    implements
+        InvalidResult,
+        SomeLibraryElementResult,
+        SomeResolvedLibraryResult {}
 
 /// The type of [InvalidResult] returned when the given file path does not
 /// represent the corresponding URI.
@@ -248,6 +262,13 @@
   VALID
 }
 
+/// The result of building the element model for a library.
+///
+/// Clients may not extend, implement or mix-in this class.
+///
+/// [LibraryElementResult] represents a valid result.
+abstract class SomeLibraryElementResult {}
+
 /// The result of building resolved AST(s) for the whole library.
 ///
 /// Clients may not extend, implement or mix-in this class.
@@ -293,6 +314,13 @@
   String get signature;
 }
 
+/// The type of [InvalidResult] returned when something is wrong, but we
+/// don't know what exactly. Usually this result should not happen.
+///
+/// Clients may not extend, implement or mix-in this class.
+class UnspecifiedInvalidResult
+    implements InvalidResult, SomeLibraryElementResult {}
+
 /// The type of [InvalidResult] returned when the given URI corresponds to
 /// a library that is served from an external summary bundle.
 ///
diff --git a/pkg/analyzer/lib/dart/analysis/session.dart b/pkg/analyzer/lib/dart/analysis/session.dart
index b0f0f77..21c2c01 100644
--- a/pkg/analyzer/lib/dart/analysis/session.dart
+++ b/pkg/analyzer/lib/dart/analysis/session.dart
@@ -44,8 +44,13 @@
 
   /// Return a future that will complete with the library element representing
   /// the library with the given [uri].
+  @Deprecated('Use getLibraryByUri2() instead')
   Future<LibraryElement> getLibraryByUri(String uri);
 
+  /// Return a future that will complete with information about the library
+  /// element representing the library with the given [uri].
+  Future<SomeLibraryElementResult> getLibraryByUri2(String uri);
+
   /// Return information about the results of parsing units of the library file
   /// with the given absolute, normalized [path].
   ///
diff --git a/pkg/analyzer/lib/src/dart/analysis/driver.dart b/pkg/analyzer/lib/src/dart/analysis/driver.dart
index 7aebf77..ed6805c 100644
--- a/pkg/analyzer/lib/src/dart/analysis/driver.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/driver.dart
@@ -619,6 +619,7 @@
   /// Throw [ArgumentError] if the [uri] does not correspond to a file.
   ///
   /// Throw [ArgumentError] if the [uri] corresponds to a part.
+  @Deprecated('Use getLibraryByUri2() instead')
   Future<LibraryElement> getLibraryByUri(String uri) async {
     var uriObj = Uri.parse(uri);
     var fileOr = _fsState.getFileForUri(uriObj);
@@ -633,7 +634,6 @@
         }
 
         var unitResult = await getUnitElement2(file.path);
-        // TODO(scheglov) this method should also return a result hierarchy
         if (unitResult is! UnitElementResult) {
           throw ArgumentError('$uri has no valid result.');
         }
@@ -647,6 +647,45 @@
     );
   }
 
+  /// Return a [Future] that completes with [LibraryElementResult] for the given
+  /// [uri], which is either resynthesized from the provided external summary
+  /// store, or built for a file to which the given [uri] is resolved.
+  Future<SomeLibraryElementResult> getLibraryByUri2(String uri) async {
+    var uriObj = Uri.parse(uri);
+    var fileOr = _fsState.getFileForUri(uriObj);
+    return fileOr.map(
+      (file) async {
+        if (file == null) {
+          return CannotResolveUriResult();
+        }
+
+        if (file.isPart) {
+          return NotLibraryButPartResult();
+        }
+
+        var unitResult = await getUnitElement2(file.path);
+        if (unitResult is UnitElementResult) {
+          return LibraryElementResultImpl(unitResult.element.library);
+        }
+
+        // Some invalid results are invalid results for this request.
+        // Note that up-down promotion does not work.
+        if (unitResult is InvalidResult &&
+            unitResult is SomeLibraryElementResult) {
+          return unitResult as SomeLibraryElementResult;
+        }
+
+        // Should not happen.
+        return UnspecifiedInvalidResult();
+      },
+      (externalLibrary) async {
+        var libraryContext = _createLibraryContext(null);
+        var element = libraryContext.getLibraryElement(externalLibrary.uri);
+        return LibraryElementResultImpl(element);
+      },
+    );
+  }
+
   /// Return a [ParsedLibraryResult] for the library with the given [path].
   ///
   /// Throw [ArgumentError] if the given [path] is not the defining compilation
diff --git a/pkg/analyzer/lib/src/dart/analysis/results.dart b/pkg/analyzer/lib/src/dart/analysis/results.dart
index 2ddf619..e55c00e 100644
--- a/pkg/analyzer/lib/src/dart/analysis/results.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/results.dart
@@ -67,6 +67,13 @@
   ResultState get state => ResultState.VALID;
 }
 
+class LibraryElementResultImpl implements LibraryElementResult {
+  @override
+  final LibraryElement element;
+
+  LibraryElementResultImpl(this.element);
+}
+
 /// The implementation of [AnalysisResult] when not [ResultState.VALID].
 class NotValidAnalysisResultImpl implements AnalysisResult {
   @override
diff --git a/pkg/analyzer/lib/src/dart/analysis/session.dart b/pkg/analyzer/lib/src/dart/analysis/session.dart
index 1d7915d..108b6cd 100644
--- a/pkg/analyzer/lib/src/dart/analysis/session.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/session.dart
@@ -70,6 +70,7 @@
     return _driver.getFileSync(path);
   }
 
+  @Deprecated('Use getLibraryByUri2() instead')
   @override
   Future<LibraryElement> getLibraryByUri(String uri) async {
     _checkConsistency();
@@ -82,6 +83,12 @@
   }
 
   @override
+  Future<SomeLibraryElementResult> getLibraryByUri2(String uri) {
+    _checkConsistency();
+    return _driver.getLibraryByUri2(uri);
+  }
+
+  @override
   ParsedLibraryResult getParsedLibrary(String path) {
     _checkConsistency();
     return _driver.getParsedLibrary(path);
diff --git a/pkg/analyzer/lib/src/dart/analysis/session_helper.dart b/pkg/analyzer/lib/src/dart/analysis/session_helper.dart
index dbaaefd..2b473c1 100644
--- a/pkg/analyzer/lib/src/dart/analysis/session_helper.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/session_helper.dart
@@ -22,13 +22,14 @@
   /// from the library with the given [libraryUri], or `null` if the library
   /// does not export a class with such name.
   Future<ClassElement?> getClass(String libraryUri, String className) async {
-    var libraryElement = await session.getLibraryByUri(libraryUri);
-    var element = libraryElement.exportNamespace.get(className);
-    if (element is ClassElement) {
-      return element;
-    } else {
-      return null;
+    var libraryResult = await session.getLibraryByUri2(libraryUri);
+    if (libraryResult is LibraryElementResult) {
+      var element = libraryResult.element.exportNamespace.get(className);
+      if (element is ClassElement) {
+        return element;
+      }
     }
+    return null;
   }
 
   /// Return the declaration of the [element], or `null` is the [element]
@@ -59,13 +60,14 @@
   /// library does not export a top-level accessor with such name.
   Future<PropertyAccessorElement?> getTopLevelPropertyAccessor(
       String uri, String name) async {
-    var libraryElement = await session.getLibraryByUri(uri);
-    var element = libraryElement.exportNamespace.get(name);
-    if (element is PropertyAccessorElement) {
-      return element;
-    } else {
-      return null;
+    var libraryResult = await session.getLibraryByUri2(uri);
+    if (libraryResult is LibraryElementResult) {
+      var element = libraryResult.element.exportNamespace.get(name);
+      if (element is PropertyAccessorElement) {
+        return element;
+      }
     }
+    return null;
   }
 
   /// Return `true` if the file with the [path] is a part.
diff --git a/pkg/analyzer/lib/src/dart/micro/analysis_context.dart b/pkg/analyzer/lib/src/dart/micro/analysis_context.dart
index a49f404..f118bed 100644
--- a/pkg/analyzer/lib/src/dart/micro/analysis_context.dart
+++ b/pkg/analyzer/lib/src/dart/micro/analysis_context.dart
@@ -9,7 +9,6 @@
 import 'package:analyzer/dart/analysis/declared_variables.dart';
 import 'package:analyzer/dart/analysis/results.dart';
 import 'package:analyzer/dart/analysis/uri_converter.dart';
-import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/dart/analysis/context_root.dart';
@@ -198,8 +197,9 @@
   }
 
   @override
-  Future<LibraryElement> getLibraryByUri(String uriStr) async {
-    return analysisContext.fileResolver.getLibraryByUri(uriStr: uriStr);
+  Future<SomeLibraryElementResult> getLibraryByUri2(String uriStr) async {
+    var element = analysisContext.fileResolver.getLibraryByUri(uriStr: uriStr);
+    return LibraryElementResultImpl(element);
   }
 
   @override
diff --git a/pkg/analyzer/test/src/dart/analysis/driver_test.dart b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
index c1dac7b..6f951ad 100644
--- a/pkg/analyzer/test/src/dart/analysis/driver_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/driver_test.dart
@@ -1423,6 +1423,7 @@
     }, throwsArgumentError);
   }
 
+  @deprecated
   test_getLibraryByUri() async {
     var a = '/test/lib/a.dart';
     var b = '/test/lib/b.dart';
@@ -1452,6 +1453,43 @@
     }, throwsArgumentError);
   }
 
+  test_getLibraryByUri2() async {
+    var a = '/test/lib/a.dart';
+    var b = '/test/lib/b.dart';
+
+    String aUriStr = 'package:test/a.dart';
+    String bUriStr = 'package:test/b.dart';
+
+    newFile(a, content: r'''
+part 'b.dart';
+
+class A {}
+''');
+
+    newFile(b, content: r'''
+part of 'a.dart';
+
+class B {}
+''');
+
+    var result = await driver.getLibraryByUri2(aUriStr);
+    result as LibraryElementResult;
+    expect(result.element.getType('A'), isNotNull);
+    expect(result.element.getType('B'), isNotNull);
+
+    // It is an error to ask for a library when we know that it is a part.
+    expect(
+      await driver.getLibraryByUri2(bUriStr),
+      isA<NotLibraryButPartResult>(),
+    );
+  }
+
+  test_getLibraryByUri2_unresolvedUri() async {
+    var result = await driver.getLibraryByUri2('package:foo/foo.dart');
+    expect(result, isA<CannotResolveUriResult>());
+  }
+
+  @deprecated
   test_getLibraryByUri_unresolvedUri() async {
     expect(() async {
       await driver.getLibraryByUri('package:foo/foo.dart');
diff --git a/pkg/analyzer/test/src/dart/analysis/search_test.dart b/pkg/analyzer/test/src/dart/analysis/search_test.dart
index 210b9b9..5b33cdf 100644
--- a/pkg/analyzer/test/src/dart/analysis/search_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/search_test.dart
@@ -1823,8 +1823,9 @@
 }
 ''');
 
-    var aLibrary = await driver.getLibraryByUri(aUri);
-    ClassElement aClass = aLibrary.getType('A')!;
+    var aLibraryResult =
+        await driver.getLibraryByUri2(aUri) as LibraryElementResult;
+    ClassElement aClass = aLibraryResult.element.getType('A')!;
 
     // Search by 'type'.
     List<SubtypeResult> subtypes =
@@ -1868,8 +1869,9 @@
     newFile(bbbFilePath, content: 'class B implements List {}');
     newFile(cccFilePath, content: 'class C implements List {}');
 
-    LibraryElement coreLib = await driver.getLibraryByUri('dart:core');
-    ClassElement listElement = coreLib.getType('List')!;
+    var coreLibResult =
+        await driver.getLibraryByUri2('dart:core') as LibraryElementResult;
+    ClassElement listElement = coreLibResult.element.getType('List')!;
 
     var searchedFiles = SearchedFiles();
     var results = await driver.search.subTypes(listElement, searchedFiles);
diff --git a/pkg/analyzer/test/src/dart/analysis/session_test.dart b/pkg/analyzer/test/src/dart/analysis/session_test.dart
index 8b85e92..6a74188 100644
--- a/pkg/analyzer/test/src/dart/analysis/session_test.dart
+++ b/pkg/analyzer/test/src/dart/analysis/session_test.dart
@@ -220,6 +220,7 @@
     expect(errorsResult.errors, isNotEmpty);
   }
 
+  @deprecated
   test_getLibraryByUri() async {
     newFile(testPath, content: r'''
 class A {}
@@ -232,6 +233,25 @@
     expect(library.getType('C'), isNull);
   }
 
+  test_getLibraryByUri2() async {
+    newFile(testPath, content: r'''
+class A {}
+class B {}
+''');
+
+    var result = await session.getLibraryByUriValid('package:test/test.dart');
+    var library = result.element;
+    expect(library.getType('A'), isNotNull);
+    expect(library.getType('B'), isNotNull);
+    expect(library.getType('C'), isNull);
+  }
+
+  test_getLibraryByUri2_unresolvedUri() async {
+    var result = await session.getLibraryByUri2('package:foo/foo.dart');
+    expect(result, isA<CannotResolveUriResult>());
+  }
+
+  @deprecated
   test_getLibraryByUri_unresolvedUri() async {
     expect(() async {
       await session.getLibraryByUri('package:foo/foo.dart');
@@ -265,10 +285,12 @@
 class B {}
 ''');
 
-    var library = await session.getLibraryByUri('package:test/test.dart');
+    var libraryResult = await session.getLibraryByUriValid(
+      'package:test/test.dart',
+    );
     var parsedLibrary = session.getParsedLibrary(testPath);
 
-    var element = library.getType('A')!;
+    var element = libraryResult.element.getType('A')!;
     var declaration = parsedLibrary.getElementDeclaration(element)!;
     var node = declaration.node as ClassDeclaration;
     expect(node.name.name, 'A');
@@ -449,7 +471,10 @@
   test_getParsedLibraryByElement() async {
     newFile(testPath, content: '');
 
-    var element = await session.getLibraryByUri('package:test/test.dart');
+    var libraryResult = await session.getLibraryByUriValid(
+      'package:test/test.dart',
+    );
+    var element = libraryResult.element;
 
     var parsedLibrary = session.getParsedLibraryByElement(element);
     expect(parsedLibrary.session, session);
@@ -461,7 +486,10 @@
   test_getParsedLibraryByElement_differentSession() async {
     newFile(testPath, content: '');
 
-    var element = await session.getLibraryByUri('package:test/test.dart');
+    var libraryResult = await session.getLibraryByUriValid(
+      'package:test/test.dart',
+    );
+    var element = libraryResult.element;
 
     var aaaSession =
         contextCollection.contextFor(aaaContextPath).currentSession;
@@ -647,7 +675,10 @@
   test_getResolvedLibraryByElement2() async {
     newFile(testPath, content: '');
 
-    var element = await session.getLibraryByUri('package:test/test.dart');
+    var libraryResult = await session.getLibraryByUriValid(
+      'package:test/test.dart',
+    );
+    var element = libraryResult.element;
 
     var result = await session.getResolvedLibraryByElementValid(element);
     expect(result.session, session);
@@ -660,7 +691,10 @@
   test_getResolvedLibraryByElement2_differentSession() async {
     newFile(testPath, content: '');
 
-    var element = await session.getLibraryByUri('package:test/test.dart');
+    var libraryResult = await session.getLibraryByUriValid(
+      'package:test/test.dart',
+    );
+    var element = libraryResult.element;
 
     var aaaSession =
         contextCollection.contextFor(aaaContextPath).currentSession;
@@ -776,6 +810,10 @@
     return await getResolvedLibrary2(path) as ResolvedLibraryResult;
   }
 
+  Future<LibraryElementResult> getLibraryByUriValid(String path) async {
+    return await getLibraryByUri2(path) as LibraryElementResult;
+  }
+
   Future<ResolvedLibraryResult> getResolvedLibraryByElementValid(
       LibraryElement element) async {
     return await getResolvedLibraryByElement2(element) as ResolvedLibraryResult;
diff --git a/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart b/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
index 84f4e90..5239e00 100644
--- a/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
+++ b/pkg/analyzer_plugin/test/src/utilities/change_builder/dart/import_library_element_test.dart
@@ -2,6 +2,7 @@
 // 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:analyzer/dart/analysis/results.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
 import 'package:test/test.dart';
@@ -467,7 +468,9 @@
     var path = convertPath('/home/test/lib/test.dart');
     newFile(path, content: initialCode);
 
-    var requestedLibrary = await session.getLibraryByUri(uriStr);
+    var requestedResult =
+        await session.getLibraryByUri2(uriStr) as LibraryElementResult;
+    var requestedLibrary = requestedResult.element;
     var requestedElement = requestedLibrary.exportNamespace.get(name);
     expect(requestedElement, isNotNull, reason: '`$name` in $uriStr');
 
diff --git a/tools/VERSION b/tools/VERSION
index f8228e6..76de4d9 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 14
 PATCH 0
-PRERELEASE 12
+PRERELEASE 13
 PRERELEASE_PATCH 0
\ No newline at end of file