From 27984095ded22e54b986d39aef8aa7bf98390644 Mon Sep 17 00:00:00 2001
From: Sam Rawlins <srawlins@google.com>
Date: Tue, 7 Mar 2023 21:12:58 +0000
Subject: [PATCH] [analysis_server] Avoid Future-of-implicit-dynamic in tests

* 99% of these are `Future ` --> `Future<void> `
* There are some `test_` methods which declare a return type of `Future` which
  is non-idiomatic, I think, but in order to create a pragmatic consistency, I
  added `<void>` to the few test methods in these libraries. Later if we
  desire, we can remove all of the return types.
* Also a few `Completer ` --> `Completer<void> ` and
  `Stream ` --> `Stream<Object?> `
* There are many remaining cases in `lib/`

Change-Id: I41cd51bab6886788e15ac7065dd21e95e789d09f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/287260
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
---
 .../notification_closing_labels_test.dart     |  4 +-
 .../analysis/notification_folding_test.dart   |  4 +-
 .../notification_implemented_test.dart        |  4 +-
 .../analysis/notification_outline_test.dart   |  4 +-
 .../channel/byte_stream_channel_test.dart     |  6 +--
 .../test/edit/organize_directives_test.dart   | 16 +++----
 .../test/edit/refactoring_test.dart           | 48 +++++++++----------
 .../test/edit/sort_members_test.dart          |  4 +-
 .../get_errors_non_standard_sdk_test.dart     |  4 +-
 .../integration/analysis/get_hover_test.dart  |  2 +-
 .../integration/analysis/highlights_test.dart |  2 +-
 .../edit/import_elements_test.dart            |  2 +-
 .../lsp_server/integration_tests.dart         |  2 +-
 .../search/get_type_hierarchy_test.dart       | 16 +++----
 .../server/blaze_changes_test.dart            |  4 +-
 .../server/command_line_options_test.dart     |  2 +-
 .../support/integration_tests.dart            | 16 +++----
 .../test/lsp/code_actions_abstract.dart       |  2 +-
 .../test/lsp/server_abstract.dart             | 16 ++++---
 pkg/analysis_server/test/mocks_lsp.dart       |  4 +-
 .../test/search/abstract_search_domain.dart   |  2 +-
 .../test/search/member_declarations_test.dart |  2 +-
 .../test/search/member_references_test.dart   |  2 +-
 .../search/top_level_declarations_test.dart   |  3 +-
 .../dart/completion_contributor_util.dart     |  2 +-
 .../dart/type_member_contributor_test.dart    |  2 +-
 .../legacy/abstract_refactoring.dart          |  6 +--
 .../legacy/convert_getter_to_method_test.dart |  4 +-
 .../legacy/convert_method_to_getter_test.dart |  4 +-
 .../legacy/extract_local_test.dart            |  4 +-
 .../legacy/extract_method_test.dart           | 10 ++--
 .../legacy/inline_method_test.dart            |  8 ++--
 .../refactoring/legacy/move_file_test.dart    |  5 +-
 .../services/search/search_engine_test.dart   |  2 +-
 .../test/socket_server_test.dart              |  2 +-
 .../test/src/cider/completion_test.dart       |  2 +-
 .../extensions/range_factory_test.dart        |  2 +-
 .../utilities/selection_coverage_test.dart    |  4 +-
 .../test/stress/utilities/server.dart         |  4 +-
 .../timing/completion/completion_simple.dart  | 10 ++--
 .../test/timing/timing_framework.dart         |  6 +--
 41 files changed, 126 insertions(+), 122 deletions(-)

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 c450726f150..fe37542b2f1 100644
--- a/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_closing_labels_test.dart
@@ -39,7 +39,7 @@ Widget build(BuildContext context) {
 
   List<ClosingLabel>? lastLabels;
 
-  late Completer _labelsReceived;
+  late Completer<void> _labelsReceived;
 
   @override
   void processNotification(Notification notification) {
@@ -47,7 +47,7 @@ Widget build(BuildContext context) {
       var params = AnalysisClosingLabelsParams.fromNotification(notification);
       if (params.file == testFile.path) {
         lastLabels = params.labels;
-        _labelsReceived.complete(null);
+        _labelsReceived.complete();
       }
     } else if (notification.event == SERVER_NOTIFICATION_ERROR) {
       var params = ServerErrorParams.fromNotification(notification);
diff --git a/pkg/analysis_server/test/analysis/notification_folding_test.dart b/pkg/analysis_server/test/analysis/notification_folding_test.dart
index 7cbda58ea29..b013d643477 100644
--- a/pkg/analysis_server/test/analysis/notification_folding_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_folding_test.dart
@@ -34,7 +34,7 @@ main async() {}
 
   List<FoldingRegion>? lastRegions;
 
-  late Completer _regionsReceived;
+  late Completer<void> _regionsReceived;
 
   @override
   void processNotification(Notification notification) {
@@ -42,7 +42,7 @@ main async() {}
       var params = AnalysisFoldingParams.fromNotification(notification);
       if (params.file == testFile.path) {
         lastRegions = params.regions;
-        _regionsReceived.complete(null);
+        _regionsReceived.complete();
       }
     } else if (notification.event == SERVER_NOTIFICATION_ERROR) {
       var params = ServerErrorParams.fromNotification(notification);
diff --git a/pkg/analysis_server/test/analysis/notification_implemented_test.dart b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
index 29c6248284b..c6ffa2f5273 100644
--- a/pkg/analysis_server/test/analysis/notification_implemented_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_implemented_test.dart
@@ -526,8 +526,8 @@ class B extends A {
     assertNoImplementedMember('m() => 0');
   }
 
-  Future waitForImplementedElements() {
-    Future waitForNotification(int times) {
+  Future<void> waitForImplementedElements() {
+    Future<void> waitForNotification(int times) {
       if (times == 0 || implementedClasses != null) {
         return Future.value();
       }
diff --git a/pkg/analysis_server/test/analysis/notification_outline_test.dart b/pkg/analysis_server/test/analysis/notification_outline_test.dart
index 8bce6e665fa..0bc81c50d15 100644
--- a/pkg/analysis_server/test/analysis/notification_outline_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_outline_test.dart
@@ -26,7 +26,7 @@ class AnalysisNotificationOutlineTest extends PubPackageAnalysisServerTest {
   Outline? outline;
 
   final Completer<void> _outlineReceived = Completer();
-  Completer? _highlightsReceived = Completer();
+  Completer<void>? _highlightsReceived = Completer();
 
   Future<void> prepareOutline() async {
     await addAnalysisSubscription(AnalysisService.OUTLINE, testFile);
@@ -47,7 +47,7 @@ class AnalysisNotificationOutlineTest extends PubPackageAnalysisServerTest {
     if (notification.event == ANALYSIS_NOTIFICATION_HIGHLIGHTS) {
       var params = AnalysisHighlightsParams.fromNotification(notification);
       if (params.file == testFile.path) {
-        _highlightsReceived?.complete(null);
+        _highlightsReceived?.complete();
         _highlightsReceived = null;
       }
     }
diff --git a/pkg/analysis_server/test/channel/byte_stream_channel_test.dart b/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
index 018145d978f..49e59dab55e 100644
--- a/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
+++ b/pkg/analysis_server/test/channel/byte_stream_channel_test.dart
@@ -114,10 +114,10 @@ class ByteStreamServerChannelTest {
   late Stream<Request> requestStream;
 
   /// Stream of errors received from the channel via [listen()].
-  late Stream errorStream;
+  late Stream<Object?> errorStream;
 
   /// Future which is completed when then [listen()] reports [onDone].
-  late Future doneFuture;
+  late Future<void> doneFuture;
 
   void setUp() {
     var inputStream = StreamController<List<int>>();
@@ -131,7 +131,7 @@ class ByteStreamServerChannelTest {
         inputStream.stream, outputSink, InstrumentationService.NULL_SERVICE);
     var requestStreamController = StreamController<Request>();
     requestStream = requestStreamController.stream;
-    var errorStreamController = StreamController();
+    var errorStreamController = StreamController<Object?>();
     errorStream = errorStreamController.stream;
     var doneCompleter = Completer();
     doneFuture = doneCompleter.future;
diff --git a/pkg/analysis_server/test/edit/organize_directives_test.dart b/pkg/analysis_server/test/edit/organize_directives_test.dart
index b9c95108252..85028509627 100644
--- a/pkg/analysis_server/test/edit/organize_directives_test.dart
+++ b/pkg/analysis_server/test/edit/organize_directives_test.dart
@@ -26,7 +26,7 @@ class OrganizeDirectivesTest extends PubPackageAnalysisServerTest {
   }
 
   @failingTest
-  Future test_BAD_doesNotExist() async {
+  Future<void> test_BAD_doesNotExist() async {
     // The analysis driver fails to return an error
     var request =
         EditOrganizeDirectivesParams(convertPath('/no/such/file.dart'))
@@ -39,7 +39,7 @@ class OrganizeDirectivesTest extends PubPackageAnalysisServerTest {
     );
   }
 
-  Future test_BAD_hasParseError() async {
+  Future<void> test_BAD_hasParseError() async {
     addTestFile('''
 import 'dart:async'
 
@@ -54,7 +54,7 @@ void f() {}
     );
   }
 
-  Future test_BAD_notDartFile() async {
+  Future<void> test_BAD_notDartFile() async {
     var request = EditOrganizeDirectivesParams(
       convertPath('/not-a-Dart-file.txt'),
     ).toRequest('0');
@@ -88,7 +88,7 @@ void f() {}
     );
   }
 
-  Future test_keep_unresolvedDirectives() {
+  Future<void> test_keep_unresolvedDirectives() {
     var code = r'''
 import 'dart:noSuchImportSdkLibrary';
 
@@ -104,7 +104,7 @@ part 'no_such_part.dart';
     return _assertOrganized(code);
   }
 
-  Future test_OK_remove_duplicateImports_withSamePrefix() {
+  Future<void> test_OK_remove_duplicateImports_withSamePrefix() {
     addTestFile('''
 library lib;
 
@@ -126,7 +126,7 @@ void f() {
 ''');
   }
 
-  Future test_OK_remove_unusedImports() {
+  Future<void> test_OK_remove_unusedImports() {
     addTestFile('''
 library lib;
 
@@ -153,13 +153,13 @@ void f() {
 ''');
   }
 
-  Future _assertOrganized(String expectedCode) async {
+  Future<void> _assertOrganized(String expectedCode) async {
     await _requestOrganize();
     var resultCode = SourceEdit.applySequence(testFileContent, fileEdit.edits);
     expect(resultCode, expectedCode);
   }
 
-  Future _requestOrganize() async {
+  Future<void> _requestOrganize() async {
     var request = EditOrganizeDirectivesParams(testFile.path).toRequest('0');
     var response = await handleSuccessfulRequest(request);
     var result = EditOrganizeDirectivesResult.fromResponse(response);
diff --git a/pkg/analysis_server/test/edit/refactoring_test.dart b/pkg/analysis_server/test/edit/refactoring_test.dart
index 4d11be4f0d5..77276eba1d4 100644
--- a/pkg/analysis_server/test/edit/refactoring_test.dart
+++ b/pkg/analysis_server/test/edit/refactoring_test.dart
@@ -810,7 +810,7 @@ int? res(int b) {
     return result.feedback as ExtractMethodFeedback;
   }
 
-  Future _prepareOptions() {
+  Future<void> _prepareOptions() {
     return getRefactoringResult(() {
       // get initial feedback
       return _sendExtractRequest();
@@ -855,7 +855,7 @@ class GetAvailableRefactoringsTest extends PubPackageAnalysisServerTest {
 
   /// Tests that there is refactoring of the given [kind] is available at the
   /// [search] offset.
-  Future assertHasKind(
+  Future<void> assertHasKind(
       String code, String search, RefactoringKind kind, bool expected) async {
     addTestFile(code);
     await waitForTasksFinished();
@@ -869,13 +869,13 @@ class GetAvailableRefactoringsTest extends PubPackageAnalysisServerTest {
   }
 
   /// Tests that there is a RENAME refactoring available at the [search] offset.
-  Future assertHasRenameRefactoring(String code, String search) async {
+  Future<void> assertHasRenameRefactoring(String code, String search) async {
     return assertHasKind(code, search, RefactoringKind.RENAME, true);
   }
 
   /// Returns the list of available refactorings for the given [offset] and
   /// [length].
-  Future getRefactorings(int offset, int length) async {
+  Future<void> getRefactorings(int offset, int length) async {
     var request =
         EditGetAvailableRefactoringsParams(testFile.path, offset, length)
             .toRequest('0');
@@ -885,12 +885,12 @@ class GetAvailableRefactoringsTest extends PubPackageAnalysisServerTest {
   }
 
   /// Returns the list of available refactorings at the offset of [search].
-  Future getRefactoringsAtString(String search) {
+  Future<void> getRefactoringsAtString(String search) {
     var offset = findOffset(search);
     return getRefactorings(offset, 0);
   }
 
-  Future getRefactoringsForString(String search) {
+  Future<void> getRefactoringsForString(String search) {
     var offset = findOffset(search);
     return getRefactorings(offset, search.length);
   }
@@ -901,13 +901,13 @@ class GetAvailableRefactoringsTest extends PubPackageAnalysisServerTest {
     await setRoots(included: [workspaceRootPath], excluded: []);
   }
 
-  Future test_convertMethodToGetter_hasElement() {
+  Future<void> test_convertMethodToGetter_hasElement() {
     return assertHasKind('''
 int getValue() => 42;
 ''', 'getValue', RefactoringKind.CONVERT_METHOD_TO_GETTER, true);
   }
 
-  Future test_extractLocal() async {
+  Future<void> test_extractLocal() async {
     addTestFile('''
 void f() {
   var a = 1 + 2;
@@ -919,7 +919,7 @@ void f() {
     expect(kinds, contains(RefactoringKind.EXTRACT_METHOD));
   }
 
-  Future test_extractLocal_withoutSelection() async {
+  Future<void> test_extractLocal_withoutSelection() async {
     addTestFile('''
 void f() {
   var a = 1 + 2;
@@ -931,7 +931,7 @@ void f() {
     expect(kinds, contains(RefactoringKind.EXTRACT_METHOD));
   }
 
-  Future test_extractWidget() async {
+  Future<void> test_extractWidget() async {
     addFlutterPackage();
     addTestFile('''
 import 'package:flutter/material.dart';
@@ -971,7 +971,7 @@ class MyWidget extends StatelessWidget {
     );
   }
 
-  Future test_rename_hasElement_class() {
+  Future<void> test_rename_hasElement_class() {
     return assertHasRenameRefactoring('''
 class Test {}
 void f() {
@@ -980,7 +980,7 @@ void f() {
 ''', 'Test v');
   }
 
-  Future test_rename_hasElement_constructor() {
+  Future<void> test_rename_hasElement_constructor() {
     return assertHasRenameRefactoring('''
 class A {
   A.test() {}
@@ -991,7 +991,7 @@ void f() {
 ''', 'test();');
   }
 
-  Future test_rename_hasElement_function() {
+  Future<void> test_rename_hasElement_function() {
     return assertHasRenameRefactoring('''
 void f() {
   test();
@@ -1000,7 +1000,7 @@ test() {}
 ''', 'test();');
   }
 
-  Future test_rename_hasElement_importElement_directive() {
+  Future<void> test_rename_hasElement_importElement_directive() {
     return assertHasRenameRefactoring('''
 import 'dart:math' as math;
 void f() {
@@ -1009,7 +1009,7 @@ void f() {
 ''', 'import ');
   }
 
-  Future test_rename_hasElement_importElement_prefixDecl() {
+  Future<void> test_rename_hasElement_importElement_prefixDecl() {
     return assertHasRenameRefactoring('''
 import 'dart:math' as math;
 void f() {
@@ -1018,7 +1018,7 @@ void f() {
 ''', 'math;');
   }
 
-  Future test_rename_hasElement_importElement_prefixRef() {
+  Future<void> test_rename_hasElement_importElement_prefixRef() {
     return assertHasRenameRefactoring('''
 import 'dart:async' as test;
 import 'dart:math' as test;
@@ -1028,7 +1028,7 @@ void f() {
 ''', 'test.pi;');
   }
 
-  Future test_rename_hasElement_instanceGetter() {
+  Future<void> test_rename_hasElement_instanceGetter() {
     return assertHasRenameRefactoring('''
 class A {
   get test => 0;
@@ -1039,7 +1039,7 @@ void f(A a) {
 ''', 'test;');
   }
 
-  Future test_rename_hasElement_instanceSetter() {
+  Future<void> test_rename_hasElement_instanceSetter() {
     return assertHasRenameRefactoring('''
 class A {
   set test(x) {}
@@ -1050,13 +1050,13 @@ void f(A a) {
 ''', 'test = 2;');
   }
 
-  Future test_rename_hasElement_library() {
+  Future<void> test_rename_hasElement_library() {
     return assertHasRenameRefactoring('''
 library my.lib;
 ''', 'library ');
   }
 
-  Future test_rename_hasElement_localVariable() {
+  Future<void> test_rename_hasElement_localVariable() {
     return assertHasRenameRefactoring('''
 void f() {
   int test = 0;
@@ -1065,7 +1065,7 @@ void f() {
 ''', 'test = 0;');
   }
 
-  Future test_rename_hasElement_method() {
+  Future<void> test_rename_hasElement_method() {
     return assertHasRenameRefactoring('''
 class A {
   test() {}
@@ -1076,7 +1076,7 @@ void f(A a) {
 ''', 'test();');
   }
 
-  Future test_rename_noElement() async {
+  Future<void> test_rename_noElement() async {
     addTestFile('''
 void f() {
   // not an element
@@ -2484,7 +2484,7 @@ void f() {
 class _AbstractGetRefactoring_Test extends PubPackageAnalysisServerTest {
   bool shouldWaitForFullAnalysis = true;
 
-  Future assertEmptySuccessfulRefactoring(
+  Future<void> assertEmptySuccessfulRefactoring(
       Future<Response> Function() requestSender,
       {void Function(RefactoringFeedback?)? feedbackValidator}) async {
     var result = await getRefactoringResult(requestSender);
@@ -2546,7 +2546,7 @@ class _AbstractGetRefactoring_Test extends PubPackageAnalysisServerTest {
     }
   }
 
-  Future assertSuccessfulRefactoring(
+  Future<void> assertSuccessfulRefactoring(
       Future<Response> Function() requestSender, String expectedCode,
       {void Function(RefactoringFeedback?)? feedbackValidator}) async {
     var result = await getRefactoringResult(requestSender);
diff --git a/pkg/analysis_server/test/edit/sort_members_test.dart b/pkg/analysis_server/test/edit/sort_members_test.dart
index 76318ea8faf..f6f0c04840a 100644
--- a/pkg/analysis_server/test/edit/sort_members_test.dart
+++ b/pkg/analysis_server/test/edit/sort_members_test.dart
@@ -262,13 +262,13 @@ class C {}
 ''');
   }
 
-  Future _assertSorted(String expectedCode) async {
+  Future<void> _assertSorted(String expectedCode) async {
     await _requestSort();
     var resultCode = SourceEdit.applySequence(testFileContent, fileEdit.edits);
     expect(resultCode, expectedCode);
   }
 
-  Future _requestSort() async {
+  Future<void> _requestSort() async {
     var request = EditSortMembersParams(testFile.path).toRequest('0');
     var response = await handleSuccessfulRequest(request);
     var result = EditSortMembersResult.fromResponse(response);
diff --git a/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart b/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
index cf21d632635..feaf93229a5 100644
--- a/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
@@ -111,7 +111,7 @@ final LIBRARIES = const <String, LibraryInfo> {
   }
 
   @override
-  Future startServer({int? diagnosticPort, int? servicePort}) {
+  Future<void> startServer({int? diagnosticPort, int? servicePort}) {
     var sdkPath = createNonStandardSdk();
     return server.start(
         diagnosticPort: diagnosticPort,
@@ -119,7 +119,7 @@ final LIBRARIES = const <String, LibraryInfo> {
         servicePort: servicePort);
   }
 
-  Future test_getErrors() async {
+  Future<void> test_getErrors() async {
     var pathname = sourcePath('test.dart');
     var text = r'''
 import 'dart:core';
diff --git a/pkg/analysis_server/test/integration/analysis/get_hover_test.dart b/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
index 793f9213081..1411432b8d8 100644
--- a/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_hover_test.dart
@@ -117,7 +117,7 @@ void f() {
 
   /// Check that a getHover request on the substring [target] produces no
   /// results.
-  Future checkNoHover(String target) {
+  Future<void> checkNoHover(String target) {
     var offset = text.indexOf(target);
     return sendAnalysisGetHover(pathname, offset).then((result) {
       expect(result.hovers, hasLength(0));
diff --git a/pkg/analysis_server/test/integration/analysis/highlights_test.dart b/pkg/analysis_server/test/integration/analysis/highlights_test.dart
index c4b67e02c22..acd0bad83b3 100644
--- a/pkg/analysis_server/test/integration/analysis/highlights_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/highlights_test.dart
@@ -47,7 +47,7 @@ class AnalysisHighlightsTest extends AbstractAnalysisServerIntegrationTest {
   }
 
   @override
-  Future startServer({
+  Future<void> startServer({
     int? diagnosticPort,
     int? servicePort,
   }) {
diff --git a/pkg/analysis_server/test/integration/edit/import_elements_test.dart b/pkg/analysis_server/test/integration/edit/import_elements_test.dart
index e6f612aa17e..db75940dd14 100644
--- a/pkg/analysis_server/test/integration/edit/import_elements_test.dart
+++ b/pkg/analysis_server/test/integration/edit/import_elements_test.dart
@@ -72,7 +72,7 @@ class AnalysisGetImportElementsIntegrationTest
   }
 
   @override
-  Future setUp() async {
+  Future<void> setUp() async {
     await super.setUp();
     pathname = sourcePath('test.dart');
   }
diff --git a/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart b/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
index fedaf4cf11d..a214d11757a 100644
--- a/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
+++ b/pkg/analysis_server/test/integration/lsp_server/integration_tests.dart
@@ -140,7 +140,7 @@ class LspServerClient {
     return dirname(pathname);
   }
 
-  Future start({
+  Future<void> start({
     required String dartSdkPath,
     List<String>? vmArgs,
   }) async {
diff --git a/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart b/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
index 987e0b8f42d..952c2e04f71 100644
--- a/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
+++ b/pkg/analysis_server/test/integration/search/get_type_hierarchy_test.dart
@@ -20,7 +20,7 @@ class GetTypeHierarchyTest extends AbstractAnalysisServerIntegrationTest {
   /// Pathname of the main file to run tests in.
   late String pathname;
 
-  Future getTypeHierarchy_badTarget() async {
+  Future<void> getTypeHierarchy_badTarget() async {
     var text = r'''
 void f() {
   if /* target */ (true) {
@@ -61,7 +61,7 @@ class Derived extends Pivot {}
     });
   }
 
-  Future getTypeHierarchy_displayName() {
+  Future<void> getTypeHierarchy_displayName() {
     var text = r'''
 class Base<T> {}
 class Pivot /* target */ extends Base<int> {}
@@ -74,7 +74,7 @@ class Pivot /* target */ extends Base<int> {}
     });
   }
 
-  Future getTypeHierarchy_functionTarget() async {
+  Future<void> getTypeHierarchy_functionTarget() async {
     var text = r'''
 main /* target */ () {
 }
@@ -83,7 +83,7 @@ main /* target */ () {
     expect(results, isNull);
   }
 
-  Future getTypeHierarchy_interfaces() {
+  Future<void> getTypeHierarchy_interfaces() {
     var text = r'''
 class Interface1 {}
 class Interface2 {}
@@ -102,7 +102,7 @@ class Pivot /* target */ implements Interface1, Interface2 {}
     });
   }
 
-  Future getTypeHierarchy_memberElement() {
+  Future<void> getTypeHierarchy_memberElement() {
     var text = r'''
 class Base1 {
   void foo /* base1 */ ();
@@ -129,7 +129,7 @@ class Derived2 extends Derived1 {
     });
   }
 
-  Future getTypeHierarchy_mixins() {
+  Future<void> getTypeHierarchy_mixins() {
     var text = r'''
 class Base {}
 class Mixin1 {}
@@ -148,7 +148,7 @@ class Pivot /* target */ extends Base with Mixin1, Mixin2 {}
     });
   }
 
-  Future getTypeHierarchy_subclasses() {
+  Future<void> getTypeHierarchy_subclasses() {
     var text = r'''
 class Base {}
 class Pivot /* target */ extends Base {}
@@ -170,7 +170,7 @@ class Sub2a extends Sub2 {}
     });
   }
 
-  Future getTypeHierarchy_superclass() {
+  Future<void> getTypeHierarchy_superclass() {
     var text = r'''
 class Base1 {}
 class Base2 extends Base1 {}
diff --git a/pkg/analysis_server/test/integration/server/blaze_changes_test.dart b/pkg/analysis_server/test/integration/server/blaze_changes_test.dart
index 20eb6a5cc52..206861ad248 100644
--- a/pkg/analysis_server/test/integration/server/blaze_changes_test.dart
+++ b/pkg/analysis_server/test/integration/server/blaze_changes_test.dart
@@ -48,7 +48,7 @@ class BlazeChangesTest extends AbstractAnalysisServerIntegrationTest {
       path.join(workspacePath, relative.replaceAll('/', path.separator));
 
   @override
-  Future setUp() async {
+  Future<void> setUp() async {
     await super.setUp();
     oldSourceDirectory = sourceDirectory;
 
@@ -78,7 +78,7 @@ class BlazeChangesTest extends AbstractAnalysisServerIntegrationTest {
   }
 
   @override
-  Future tearDown() async {
+  Future<void> tearDown() async {
     Directory(tmpPath).deleteSync(recursive: true);
     sourceDirectory = oldSourceDirectory;
     await super.tearDown();
diff --git a/pkg/analysis_server/test/integration/server/command_line_options_test.dart b/pkg/analysis_server/test/integration/server/command_line_options_test.dart
index 6da432df13a..0b252fec27d 100644
--- a/pkg/analysis_server/test/integration/server/command_line_options_test.dart
+++ b/pkg/analysis_server/test/integration/server/command_line_options_test.dart
@@ -20,7 +20,7 @@ void main() {
 class OptionsPackagesIntegrationTest
     extends AbstractAnalysisServerIntegrationTest {
   @override
-  Future startServer({int? diagnosticPort, int? servicePort}) {
+  Future<void> startServer({int? diagnosticPort, int? servicePort}) {
     var fooPath = sourcePath('foo');
     writeFile(
       path.join(fooPath, 'lib', 'foo.dart'),
diff --git a/pkg/analysis_server/test/integration/support/integration_tests.dart b/pkg/analysis_server/test/integration/support/integration_tests.dart
index f45b3e110bf..91fd8b6f1a8 100644
--- a/pkg/analysis_server/test/integration/support/integration_tests.dart
+++ b/pkg/analysis_server/test/integration/support/integration_tests.dart
@@ -155,14 +155,14 @@ abstract class AbstractAnalysisServerIntegrationTest extends IntegrationTest {
   String readFile(String pathname) => File(pathname).readAsStringSync();
 
   @override
-  Future sendServerSetSubscriptions(List<ServerService> subscriptions) {
+  Future<void> sendServerSetSubscriptions(List<ServerService> subscriptions) {
     _subscribedToServerStatus = subscriptions.contains(ServerService.STATUS);
     return super.sendServerSetSubscriptions(subscriptions);
   }
 
   /// The server is automatically started before every test, and a temporary
   /// [sourceDirectory] is created.
-  Future setUp() async {
+  Future<void> setUp() async {
     sourceDirectory = Directory(Directory.systemTemp
         .createTempSync('analysisServer')
         .resolveSymbolicLinksSync());
@@ -192,7 +192,7 @@ abstract class AbstractAnalysisServerIntegrationTest extends IntegrationTest {
   }
 
   /// If [skipShutdown] is not set, shut down the server.
-  Future shutdownIfNeeded() {
+  Future<void> shutdownIfNeeded() {
     if (skipShutdown) {
       return Future.value();
     }
@@ -218,8 +218,8 @@ abstract class AbstractAnalysisServerIntegrationTest extends IntegrationTest {
   /// analyze [sourceDirectory].  If [subscribeStatus] is true (the default),
   /// then also enable [SERVER_NOTIFICATION_STATUS] notifications so that
   /// [analysisFinished] can be used.
-  Future standardAnalysisSetup({bool subscribeStatus = true}) {
-    var futures = <Future>[];
+  Future<void> standardAnalysisSetup({bool subscribeStatus = true}) {
+    var futures = <Future<void>>[];
     if (subscribeStatus) {
       futures.add(sendServerSetSubscriptions([ServerService.STATUS]));
     }
@@ -228,7 +228,7 @@ abstract class AbstractAnalysisServerIntegrationTest extends IntegrationTest {
   }
 
   /// Start [server].
-  Future startServer({
+  Future<void> startServer({
     int? diagnosticPort,
     int? servicePort,
   }) {
@@ -240,7 +240,7 @@ abstract class AbstractAnalysisServerIntegrationTest extends IntegrationTest {
   }
 
   /// After every test, the server is stopped and [sourceDirectory] is deleted.
-  Future tearDown() {
+  Future<void> tearDown() {
     return shutdownIfNeeded().then((_) {
       sourceDirectory.deleteSync(recursive: true);
     });
@@ -496,7 +496,7 @@ class Server {
 
   /// Return a future that will complete when all commands that have been sent
   /// to the server so far have been flushed to the OS buffer.
-  Future flushCommands() {
+  Future<void> flushCommands() {
     return _process.stdin.flush();
   }
 
diff --git a/pkg/analysis_server/test/lsp/code_actions_abstract.dart b/pkg/analysis_server/test/lsp/code_actions_abstract.dart
index 436f3ace1d3..679194e89fa 100644
--- a/pkg/analysis_server/test/lsp/code_actions_abstract.dart
+++ b/pkg/analysis_server/test/lsp/code_actions_abstract.dart
@@ -135,7 +135,7 @@ abstract class AbstractCodeActionsTest extends AbstractLspAnalysisServerTest {
   /// Verifies that executing the given code actions command on the server
   /// results in an edit being sent to the client that updates the file to match
   /// the expected content.
-  Future verifyCodeActionEdits(Either2<Command, CodeAction> codeAction,
+  Future<void> verifyCodeActionEdits(Either2<Command, CodeAction> codeAction,
       String content, String expectedContent,
       {bool expectDocumentChanges = false,
       ProgressToken? workDoneToken}) async {
diff --git a/pkg/analysis_server/test/lsp/server_abstract.dart b/pkg/analysis_server/test/lsp/server_abstract.dart
index 0cd49dec0ba..7dab5c19fd2 100644
--- a/pkg/analysis_server/test/lsp/server_abstract.dart
+++ b/pkg/analysis_server/test/lsp/server_abstract.dart
@@ -165,7 +165,8 @@ abstract class AbstractLspAnalysisServerTest
   }
 
   @override
-  Future sendNotificationToServer(NotificationMessage notification) async {
+  Future<void> sendNotificationToServer(
+      NotificationMessage notification) async {
     channel.sendNotificationToServer(notification);
     await pumpEventQueue(times: 5000);
   }
@@ -228,7 +229,7 @@ analyzer:
     writePackageConfig(projectFolderPath);
   }
 
-  Future tearDown() async {
+  Future<void> tearDown() async {
     channel.close();
     await server.shutdown();
   }
@@ -915,7 +916,7 @@ mixin LspAnalysisServerTestMixin implements ClientCapabilitiesHelperMixin {
         request, _fromJsonList(CallHierarchyOutgoingCall.fromJson));
   }
 
-  Future changeFile(
+  Future<void> changeFile(
     int newVersion,
     Uri uri,
     List<TextDocumentContentChangeEvent> changes,
@@ -931,7 +932,8 @@ mixin LspAnalysisServerTestMixin implements ClientCapabilitiesHelperMixin {
     await sendNotificationToServer(notification);
   }
 
-  Future changeWorkspaceFolders({List<Uri>? add, List<Uri>? remove}) async {
+  Future<void> changeWorkspaceFolders(
+      {List<Uri>? add, List<Uri>? remove}) async {
     var notification = makeNotification(
       Method.workspace_didChangeWorkspaceFolders,
       DidChangeWorkspaceFoldersParams(
@@ -944,7 +946,7 @@ mixin LspAnalysisServerTestMixin implements ClientCapabilitiesHelperMixin {
     await sendNotificationToServer(notification);
   }
 
-  Future closeFile(Uri uri) async {
+  Future<void> closeFile(Uri uri) async {
     var notification = makeNotification(
       Method.textDocument_didClose,
       DidCloseTextDocumentParams(
@@ -1698,7 +1700,7 @@ mixin LspAnalysisServerTestMixin implements ClientCapabilitiesHelperMixin {
     return expectSuccessfulResponseTo(request, WorkspaceEdit.fromJson);
   }
 
-  Future openFile(Uri uri, String content, {int version = 1}) async {
+  Future<void> openFile(Uri uri, String content, {int version = 1}) async {
     var notification = makeNotification(
       Method.textDocument_didOpen,
       DidOpenTextDocumentParams(
@@ -1903,7 +1905,7 @@ mixin LspAnalysisServerTestMixin implements ClientCapabilitiesHelperMixin {
     return sendRequestToServer(request);
   }
 
-  Future replaceFile(int newVersion, Uri uri, String content) {
+  Future<void> replaceFile(int newVersion, Uri uri, String content) {
     return changeFile(
       newVersion,
       uri,
diff --git a/pkg/analysis_server/test/mocks_lsp.dart b/pkg/analysis_server/test/mocks_lsp.dart
index 857639fe1f6..6e2931c1929 100644
--- a/pkg/analysis_server/test/mocks_lsp.dart
+++ b/pkg/analysis_server/test/mocks_lsp.dart
@@ -16,7 +16,7 @@ class MockLspServerChannel implements LspServerCommunicationChannel {
       StreamController<lsp.Message>.broadcast();
 
   /// Completer that will be signalled when the input stream is closed.
-  final Completer _closed = Completer();
+  final Completer<void> _closed = Completer();
 
   /// Errors popups sent to the user.
   final shownErrors = <lsp.ShowMessageParams>[];
@@ -51,7 +51,7 @@ class MockLspServerChannel implements LspServerCommunicationChannel {
 
   /// Future that will be completed when the input stream is closed.
   @override
-  Future get closed {
+  Future<void> get closed {
     return _closed.future;
   }
 
diff --git a/pkg/analysis_server/test/search/abstract_search_domain.dart b/pkg/analysis_server/test/search/abstract_search_domain.dart
index 70b5071b696..68cf80baac8 100644
--- a/pkg/analysis_server/test/search/abstract_search_domain.dart
+++ b/pkg/analysis_server/test/search/abstract_search_domain.dart
@@ -84,7 +84,7 @@ class AbstractSearchDomainTest extends PubPackageAnalysisServerTest {
     await setRoots(included: [workspaceRootPath], excluded: []);
   }
 
-  Future waitForSearchResults() {
+  Future<void> waitForSearchResults() {
     var resultSet = _resultSets[searchId];
     if (resultSet != null && resultSet.done) {
       results = resultSet.results;
diff --git a/pkg/analysis_server/test/search/member_declarations_test.dart b/pkg/analysis_server/test/search/member_declarations_test.dart
index 33ae643e461..d58f3f5b761 100644
--- a/pkg/analysis_server/test/search/member_declarations_test.dart
+++ b/pkg/analysis_server/test/search/member_declarations_test.dart
@@ -25,7 +25,7 @@ class MemberDeclarationsTest extends AbstractSearchDomainTest {
     this.result = result;
   }
 
-  Future findMemberDeclarations(String name) async {
+  Future<void> findMemberDeclarations(String name) async {
     await waitForTasksFinished();
     var request = SearchFindMemberDeclarationsParams(name).toRequest('0');
     var response = await handleSuccessfulRequest(request);
diff --git a/pkg/analysis_server/test/search/member_references_test.dart b/pkg/analysis_server/test/search/member_references_test.dart
index a3a5d9413f8..e18d659cc74 100644
--- a/pkg/analysis_server/test/search/member_references_test.dart
+++ b/pkg/analysis_server/test/search/member_references_test.dart
@@ -21,7 +21,7 @@ class MemberReferencesTest extends AbstractSearchDomainTest {
     expect(result.isPotential, isPotential);
   }
 
-  Future findMemberReferences(String name) async {
+  Future<void> findMemberReferences(String name) async {
     await waitForTasksFinished();
     var request = SearchFindMemberReferencesParams(name).toRequest('0');
     var response = await handleSuccessfulRequest(request);
diff --git a/pkg/analysis_server/test/search/top_level_declarations_test.dart b/pkg/analysis_server/test/search/top_level_declarations_test.dart
index c6d28b3c5c3..2993836a1b5 100644
--- a/pkg/analysis_server/test/search/top_level_declarations_test.dart
+++ b/pkg/analysis_server/test/search/top_level_declarations_test.dart
@@ -32,7 +32,8 @@ class TopLevelDeclarationsTest extends AbstractSearchDomainTest {
     }
   }
 
-  Future findTopLevelDeclarations(String pattern) async {
+  Future<dynamic /*RequestError?|void*/ > findTopLevelDeclarations(
+      String pattern) async {
     await waitForTasksFinished();
     var request = SearchFindTopLevelDeclarationsParams(pattern).toRequest('0');
     var response = await handleRequest(request);
diff --git a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
index b9724851c44..090cece530e 100644
--- a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
+++ b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
@@ -560,7 +560,7 @@ abstract class _BaseDartCompletionContributorTest extends AbstractContextTest {
   Future<List<CompletionSuggestion>> computeContributedSuggestions(
       DartCompletionRequest request);
 
-  Future computeSuggestions({int times = 200}) async {
+  Future<void> computeSuggestions({int times = 200}) async {
     result = await getResolvedUnit(testFile);
 
     // Build the request
diff --git a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
index 8eec01cbc90..8199f52dd57 100644
--- a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
@@ -28,7 +28,7 @@ class TypeMemberContributorTest extends DartCompletionContributorTest {
   /// shadows a declaration of the form [shadowee] in a base class, for the
   /// purposes of what is shown during completion.  [shouldBeShadowed] indicates
   /// whether shadowing is expected.
-  Future check_shadowing(
+  Future<void> check_shadowing(
       String shadower, String shadowee, bool shouldBeShadowed) async {
     addTestSource('''
 class Base {
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/abstract_refactoring.dart b/pkg/analysis_server/test/services/refactoring/legacy/abstract_refactoring.dart
index 32762880f2a..5302ad10ad6 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/abstract_refactoring.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/abstract_refactoring.dart
@@ -62,7 +62,7 @@ abstract class RefactoringTest extends AbstractSingleUnitTest {
   }
 
   /// Asserts that [refactoring] initial/final conditions status is OK.
-  Future assertRefactoringConditionsOK() async {
+  Future<void> assertRefactoringConditionsOK() async {
     var status = await refactoring.checkInitialConditions();
     assertRefactoringStatusOK(status);
     status = await refactoring.checkFinalConditions();
@@ -70,7 +70,7 @@ abstract class RefactoringTest extends AbstractSingleUnitTest {
   }
 
   /// Asserts that [refactoring] final conditions status is OK.
-  Future assertRefactoringFinalConditionsOK() async {
+  Future<void> assertRefactoringFinalConditionsOK() async {
     var status = await refactoring.checkFinalConditions();
     assertRefactoringStatusOK(status);
   }
@@ -110,7 +110,7 @@ abstract class RefactoringTest extends AbstractSingleUnitTest {
 
   /// Checks that all conditions of [refactoring] are OK and the result of
   /// applying the [Change] to [testUnit] is [expectedCode].
-  Future assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> assertSuccessfulRefactoring(String expectedCode) async {
     await assertRefactoringConditionsOK();
     var change = await refactoring.createChange();
     refactoringChange = change;
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/convert_getter_to_method_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/convert_getter_to_method_test.dart
index 4d8bb07249f..b68b7071116 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/convert_getter_to_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/convert_getter_to_method_test.dart
@@ -174,7 +174,7 @@ void f() {
         'Only explicit getters can be converted to methods.');
   }
 
-  Future _assertInitialConditions_fatal(String message) async {
+  Future<void> _assertInitialConditions_fatal(String message) async {
     var status = await refactoring.checkInitialConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
         expectedMessage: message);
@@ -182,7 +182,7 @@ void f() {
 
   /// Checks that all conditions are OK and the result of applying [refactoring]
   /// change to [testUnit] is [expectedCode].
-  Future _assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> _assertSuccessfulRefactoring(String expectedCode) async {
     await assertRefactoringConditionsOK();
     var refactoringChange = await refactoring.createChange();
     this.refactoringChange = refactoringChange;
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/convert_method_to_getter_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/convert_method_to_getter_test.dart
index e4d61a971d6..78edddb0c20 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/convert_method_to_getter_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/convert_method_to_getter_test.dart
@@ -204,7 +204,7 @@ void test() {}
         'Cannot convert function returning void.');
   }
 
-  Future _assertInitialConditions_fatal(String message) async {
+  Future<void> _assertInitialConditions_fatal(String message) async {
     var status = await refactoring.checkInitialConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
         expectedMessage: message);
@@ -212,7 +212,7 @@ void test() {}
 
   /// Checks that all conditions are OK and the result of applying the [Change]
   /// to [testUnit] is [expectedCode].
-  Future _assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> _assertSuccessfulRefactoring(String expectedCode) async {
     await assertRefactoringConditionsOK();
     var refactoringChange = await refactoring.createChange();
     this.refactoringChange = refactoringChange;
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/extract_local_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/extract_local_test.dart
index c770276cad7..1575f309a28 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/extract_local_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/extract_local_test.dart
@@ -1454,7 +1454,7 @@ void f() {
     _assertSingleLinkedEditGroup(length: 3, offsets: [43, 69], names: ['xy']);
   }
 
-  Future _assertInitialConditions_fatal_selection() async {
+  Future<void> _assertInitialConditions_fatal_selection() async {
     var status = await refactoring.checkInitialConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
         expectedMessage:
@@ -1485,7 +1485,7 @@ void f() {
 
   /// Checks that all conditions are OK and the result of applying the
   /// [SourceChange] to [testUnit] is [expectedCode].
-  Future _assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> _assertSuccessfulRefactoring(String expectedCode) async {
     await assertRefactoringConditionsOK();
     var refactoringChange = await refactoring.createChange();
     this.refactoringChange = refactoringChange;
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/extract_method_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/extract_method_test.dart
index 4dd6c45dbe9..0629e714eb8 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/extract_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/extract_method_test.dart
@@ -3299,25 +3299,25 @@ class _ExtractMethodTest extends RefactoringTest {
   @override
   late ExtractMethodRefactoringImpl refactoring;
 
-  Future _assertConditionsError(String message) async {
+  Future<void> _assertConditionsError(String message) async {
     var status = await refactoring.checkAllConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR,
         expectedMessage: message);
   }
 
-  Future _assertConditionsFatal(String message) async {
+  Future<void> _assertConditionsFatal(String message) async {
     var status = await refactoring.checkAllConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
         expectedMessage: message);
   }
 
-  Future _assertFinalConditionsError(String message) async {
+  Future<void> _assertFinalConditionsError(String message) async {
     var status = await refactoring.checkFinalConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR,
         expectedMessage: message);
   }
 
-  Future _assertRefactoringChange(String expectedCode) async {
+  Future<void> _assertRefactoringChange(String expectedCode) async {
     var refactoringChange = await refactoring.createChange();
     this.refactoringChange = refactoringChange;
     assertTestChangeResult(expectedCode);
@@ -3325,7 +3325,7 @@ class _ExtractMethodTest extends RefactoringTest {
 
   /// Checks that all conditions are OK and the result of applying the [Change]
   /// to [testUnit] is [expectedCode].
-  Future _assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> _assertSuccessfulRefactoring(String expectedCode) async {
     await assertRefactoringConditionsOK();
     refactoring.createGetter = false;
     return _assertRefactoringChange(expectedCode);
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/inline_method_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/inline_method_test.dart
index 80d5ce6acfb..da02f74e126 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/inline_method_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/inline_method_test.dart
@@ -1884,24 +1884,24 @@ class _InlineMethodTest extends RefactoringTest {
   bool? deleteSource;
   bool? inlineAll;
 
-  Future _assertConditionsError(String message) async {
+  Future<void> _assertConditionsError(String message) async {
     var status = await refactoring.checkAllConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.ERROR,
         expectedMessage: message);
   }
 
-  Future _assertConditionsFatal(String message) async {
+  Future<void> _assertConditionsFatal(String message) async {
     var status = await refactoring.checkAllConditions();
     assertRefactoringStatus(status, RefactoringProblemSeverity.FATAL,
         expectedMessage: message);
   }
 
-  Future _assertInvalidSelection() {
+  Future<void> _assertInvalidSelection() {
     return _assertConditionsFatal(
         'Method declaration or reference must be selected to activate this refactoring.');
   }
 
-  Future _assertSuccessfulRefactoring(String expectedCode) async {
+  Future<void> _assertSuccessfulRefactoring(String expectedCode) async {
     var status = await refactoring.checkInitialConditions();
     assertRefactoringStatusOK(status);
     // configure
diff --git a/pkg/analysis_server/test/services/refactoring/legacy/move_file_test.dart b/pkg/analysis_server/test/services/refactoring/legacy/move_file_test.dart
index 00b493b1c28..56266c23b11 100644
--- a/pkg/analysis_server/test/services/refactoring/legacy/move_file_test.dart
+++ b/pkg/analysis_server/test/services/refactoring/legacy/move_file_test.dart
@@ -527,7 +527,8 @@ part 'test2.dart';
     assertNoFileChange(testFile);
   }
 
-  Future _assertFailedRefactoring(RefactoringProblemSeverity expectedSeverity,
+  Future<void> _assertFailedRefactoring(
+      RefactoringProblemSeverity expectedSeverity,
       {String? expectedMessage}) async {
     var status = await refactoring.checkAllConditions();
     assertRefactoringStatus(status, expectedSeverity,
@@ -535,7 +536,7 @@ part 'test2.dart';
   }
 
   /// Checks that all conditions are OK.
-  Future _assertSuccessfulRefactoring() async {
+  Future<void> _assertSuccessfulRefactoring() async {
     await assertRefactoringConditionsOK();
     refactoringChange = await refactoring.createChange();
   }
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 a893096b47d..4c92d1061fa 100644
--- a/pkg/analysis_server/test/services/search/search_engine_test.dart
+++ b/pkg/analysis_server/test/services/search/search_engine_test.dart
@@ -581,7 +581,7 @@ class B extends A {}
     return aaaRootPath;
   }
 
-  Future _ensureContainedFilesKnown() async {
+  Future<void> _ensureContainedFilesKnown() async {
     for (var driver in allDrivers) {
       var contextRoot = driver.analysisContext!.contextRoot;
       for (var file in contextRoot.analyzedFiles()) {
diff --git a/pkg/analysis_server/test/socket_server_test.dart b/pkg/analysis_server/test/socket_server_test.dart
index 8623c877daa..87c537da486 100644
--- a/pkg/analysis_server/test/socket_server_test.dart
+++ b/pkg/analysis_server/test/socket_server_test.dart
@@ -49,7 +49,7 @@ class SocketServerTest {
     });
   }
 
-  static Future createAnalysisServer_successful() {
+  static Future<void> createAnalysisServer_successful() {
     var channel = MockServerChannel();
     _createSocketServer(channel);
     channel.expectMsgCount(notificationCount: 1);
diff --git a/pkg/analysis_server/test/src/cider/completion_test.dart b/pkg/analysis_server/test/src/cider/completion_test.dart
index 13465ac7ad2..5d16c5a173e 100644
--- a/pkg/analysis_server/test/src/cider/completion_test.dart
+++ b/pkg/analysis_server/test/src/cider/completion_test.dart
@@ -788,7 +788,7 @@ import 'a.dart';
     }
   }
 
-  Future _compute(String content) async {
+  Future<void> _compute(String content) async {
     var context = _updateFile(content);
 
     _completionResult = await _newComputer().compute(
diff --git a/pkg/analysis_server/test/src/utilities/extensions/range_factory_test.dart b/pkg/analysis_server/test/src/utilities/extensions/range_factory_test.dart
index 015bfa49fff..762e025834c 100644
--- a/pkg/analysis_server/test/src/utilities/extensions/range_factory_test.dart
+++ b/pkg/analysis_server/test/src/utilities/extensions/range_factory_test.dart
@@ -987,7 +987,7 @@ int bar = 2; // 2
   }
 }
 
-class _NodesCollector extends UnifyingAstVisitor {
+class _NodesCollector extends UnifyingAstVisitor<void> {
   final bool Function(AstNode) filter;
   final List<AstNode> _nodes = [];
 
diff --git a/pkg/analysis_server/test/src/utilities/selection_coverage_test.dart b/pkg/analysis_server/test/src/utilities/selection_coverage_test.dart
index 3ca45a50265..495803bf8ff 100644
--- a/pkg/analysis_server/test/src/utilities/selection_coverage_test.dart
+++ b/pkg/analysis_server/test/src/utilities/selection_coverage_test.dart
@@ -238,13 +238,13 @@ class SelectionData {
   SelectionData();
 }
 
-class VisitMethodVisitor extends RecursiveAstVisitor {
+class VisitMethodVisitor extends RecursiveAstVisitor<void> {
   List<ExecutableElement> visitedLists = [];
 
   VisitMethodVisitor();
 
   @override
-  visitMethodInvocation(MethodInvocation node) {
+  void visitMethodInvocation(MethodInvocation node) {
     if (node.methodName.name == '_fromList') {
       var argument = node.argumentList.arguments.first;
       if (argument is PrefixedIdentifier) {
diff --git a/pkg/analysis_server/test/stress/utilities/server.dart b/pkg/analysis_server/test/stress/utilities/server.dart
index f47f6658908..5671c21ec50 100644
--- a/pkg/analysis_server/test/stress/utilities/server.dart
+++ b/pkg/analysis_server/test/stress/utilities/server.dart
@@ -165,7 +165,7 @@ class Server {
   /// are received after this function call, so it is safe to use this getter
   /// multiple times in one test; each time it is used it will wait afresh for
   /// analysis to finish.
-  Future get analysisFinished {
+  Future<void> get analysisFinished {
     var completer = _analysisFinishedCompleter ??= Completer<void>();
     return completer.future;
   }
@@ -201,7 +201,7 @@ class Server {
   /// [filePaths] to the list of errors in the file at that path.
   Future<ErrorMap> computeErrorMap(List<String> filePaths) async {
     var errorMap = ErrorMap();
-    var futures = <Future>[];
+    var futures = <Future<void>>[];
     for (var filePath in filePaths) {
       var requestData = sendAnalysisGetErrors(filePath);
       futures.add(requestData.respondedTo.then((Response response) {
diff --git a/pkg/analysis_server/test/timing/completion/completion_simple.dart b/pkg/analysis_server/test/timing/completion/completion_simple.dart
index 3984325487b..081289f1deb 100644
--- a/pkg/analysis_server/test/timing/completion/completion_simple.dart
+++ b/pkg/analysis_server/test/timing/completion/completion_simple.dart
@@ -39,13 +39,13 @@ class SimpleTest extends TimingTest {
 
   /// A completer that will be completed when code completion results have been
   /// received from the server.
-  late Completer completionReceived;
+  late Completer<void> completionReceived;
 
   /// Initialize a newly created test.
   SimpleTest();
 
   @override
-  Future oneTimeSetUp() {
+  Future<void> oneTimeSetUp() {
     return super.oneTimeSetUp().then((_) {
       mainFilePath = sourcePath('test.dart');
       originalContent = r'''
@@ -65,7 +65,7 @@ f(C c) {
   }
 
   @override
-  Future perform() {
+  Future<void> perform() {
     sendAnalysisUpdateContent({
       mainFilePath: ChangeContentOverlay([SourceEdit(cursorOffset, 0, '.')])
     });
@@ -74,7 +74,7 @@ f(C c) {
   }
 
   @override
-  Future setUp() {
+  Future<void> setUp() {
     completionReceived = Completer();
     onCompletionResults.listen((_) {
       // We only care about the time to the first response.
@@ -89,7 +89,7 @@ f(C c) {
   }
 
   @override
-  Future tearDown() {
+  Future<void> tearDown() {
     sendAnalysisSetAnalysisRoots([], []);
     return Future.value();
   }
diff --git a/pkg/analysis_server/test/timing/timing_framework.dart b/pkg/analysis_server/test/timing/timing_framework.dart
index 7b8a548c49f..2f53a53d5a9 100644
--- a/pkg/analysis_server/test/timing/timing_framework.dart
+++ b/pkg/analysis_server/test/timing/timing_framework.dart
@@ -163,7 +163,7 @@ abstract class TimingTest extends IntegrationTest {
 
   /// Perform any operations that part of a single iteration. It is the
   /// execution of this method that will be measured.
-  Future perform();
+  Future<void> perform();
 
   /// Return a future that will complete with a timing result representing the
   /// number of milliseconds required to perform the operation the specified
@@ -178,7 +178,7 @@ abstract class TimingTest extends IntegrationTest {
   }
 
   /// Perform any operations that need to be performed before each iteration.
-  Future setUp();
+  Future<void> setUp();
 
   /// Convert the given [relativePath] to an absolute path, by interpreting it
   /// relative to [sourceDirectory].  On Windows any forward slashes in
@@ -188,7 +188,7 @@ abstract class TimingTest extends IntegrationTest {
   }
 
   /// Perform any operations that need to be performed after each iteration.
-  Future tearDown();
+  Future<void> tearDown();
 
   /// Write a source file with the given absolute [pathname] and [contents].
   ///