Convert multitests in core platform library tests.

A little extra clean-up in related files.

Change-Id: I1d0d809d1ab4d756470e3a292e8e070ef31304af
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402660
Commit-Queue: Lasse Nielsen <[email protected]>
Reviewed-by: Bob Nystrom <[email protected]>
Reviewed-by: Nate Bosch <[email protected]>

Author: lrhn

tests/lib/async/catch_errors.dart

@@ -6,25 +6,36 @@ library catch_errors;
 
 import 'dart:async';
 
-Stream catchErrors(dynamic body()) {
-  late StreamController controller;
-
-  bool onError(e, st) {
-    controller.add(e);
-    return true;
-  }
-
-  void onListen() {
-    runZonedGuarded(body, onError);
-  }
-
-  controller = new StreamController(onListen: onListen);
+/// Runs [body] inside [runZonedGuarded].
+///
+/// Runs [body] when the returned stream is listened to.
+/// Emits all errors, synchronous and asynchronous,
+/// as events on the returned stream.
+///
+/// **Notice**: The stream never closes. The caller should stop
+/// listening when they're convinced there will be no later error events.
+Stream<Object> catchErrors(void Function() body) {
+  var controller = StreamController<Object>();
+  controller.onListen = () {
+    runZonedGuarded(body, (e, s) {
+      controller.add(e);
+    });
+  };
   return controller.stream;
 }
 
-runZonedScheduleMicrotask(
-  body(), {
-  void onScheduleMicrotask(void callback())?,
+/// Runs [body] inside [runZoneGuarded], [Zone.runGuarded] or [Zone.run].
+///
+/// If [onScheduleMicrotask] is provided, a custom zone is created
+/// with a [Zone.scheduleMicrotask] which calls [onScheduleMicrotask] with
+/// the provided callback.
+///
+/// If [onError] is provided, it's used as argument to [runZonedGuarded]
+/// or as error handler of the custom zone, and the `body` is then run
+/// using `runGuarded`.
+R? runZonedScheduleMicrotask<R>(
+  R body(), {
+  void Function(void Function() callback)? onScheduleMicrotask,
   Function? onError,
 }) {
   if (onScheduleMicrotask == null) {
@@ -56,18 +67,20 @@ runZonedScheduleMicrotask(
   }
   ScheduleMicrotaskHandler? asyncHandler;
   if (onScheduleMicrotask != null) {
-    asyncHandler = (Zone self, ZoneDelegate parent, Zone zone, f()) {
+    void handle(Zone self, ZoneDelegate parent, Zone zone, Function() f) {
       self.parent!.runUnary(onScheduleMicrotask, () => zone.runGuarded(f));
-    };
+    }
+
+    asyncHandler = handle;
   }
-  ZoneSpecification specification = new ZoneSpecification(
+  ZoneSpecification specification = ZoneSpecification(
     handleUncaughtError: errorHandler,
     scheduleMicrotask: asyncHandler,
   );
-  Zone zone = Zone.current.fork(specification: specification);
   if (onError != null) {
-    return zone.runGuarded(body);
+    return runZoned<R>(body, zoneSpecification: specification);
   } else {
-    return zone.run(body);
+    Zone zone = Zone.current.fork(specification: specification);
+    return zone.run<R>(body);
   }
 }

tests/lib/async/catch_errors11_test.dart

@@ -9,15 +9,15 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
   // Test that `catchErrors` catches errors that are delayed by `Timer.run`.
   catchErrors(() {
     events.add("catch error entry");
-    new Future.error("future error");
+    Future.error("future error");
     Timer.run(() {
       done.complete(true);
       throw "timer error";

tests/lib/async/catch_errors12_test.dart

@@ -9,9 +9,9 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
   // Tests that errors that have been delayed by several milliseconds with
@@ -21,11 +21,11 @@ main() {
     Timer.run(() {
       throw "timer error";
     });
-    new Timer(const Duration(milliseconds: 100), () {
+    Timer(const Duration(milliseconds: 100), () {
       throw "timer2 error";
     });
-    new Future.value(499).then((x) {
-      new Timer(const Duration(milliseconds: 200), () {
+    Future.value(499).then((x) {
+      Timer(const Duration(milliseconds: 200), () {
         done.complete(499);
         throw x;
       });

tests/lib/async/catch_errors13_test.dart

@@ -9,9 +9,9 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
   // Work around bug that makes scheduleMicrotask use Timers. By invoking
@@ -40,7 +40,7 @@ main() {
       // This way we could reduce the timeout (to 10ms now), while still
       // allowing for more time, in case the machine is slow.
       void runDelayed() {
-        new Timer(const Duration(milliseconds: 10), () {
+        Timer(const Duration(milliseconds: 10), () {
           if (outerTimerRan) {
             scheduleMicrotask(() {
               throw "scheduleMicrotask";

tests/lib/async/catch_errors14_test.dart

@@ -9,15 +9,15 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
   // Test that periodic Timers are handled correctly by `catchErrors`.
   catchErrors(() {
     int counter = 0;
-    new Timer.periodic(const Duration(milliseconds: 50), (timer) {
+    Timer.periodic(const Duration(milliseconds: 50), (timer) {
       if (counter++ == 5) {
         timer.cancel();
         done.complete(true);

tests/lib/async/catch_errors15_test.dart

@@ -9,19 +9,19 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
   var events = [];
 
   catchErrors(() {
     events.add("catch error entry");
     catchErrors(() {
       events.add("catch error entry2");
-      new Future.error("future error");
-      new Future.error("future error2");
-      new Future.value(499).then((x) => throw x);
-      new Future.delayed(const Duration(milliseconds: 50), () {
+      Future.error("future error");
+      Future.error("future error2");
+      Future.value(499).then((x) => throw x);
+      Future.delayed(const Duration(milliseconds: 50), () {
         throw "delayed error";
       });
       throw "catch error";

tests/lib/async/catch_errors16_test.dart

@@ -9,10 +9,10 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
   var events = [];
-  StreamController controller = new StreamController();
+  StreamController controller = StreamController();
   Stream stream = controller.stream;
   // Test that the subscription of a stream is what counts. The error (2) runs
   // through the map-stream which goes through the nested `catchError` but
@@ -24,7 +24,7 @@ main() {
   });
   stream
       .transform(
-        new StreamTransformer.fromHandlers(
+        StreamTransformer.fromHandlers(
           handleError: (e, st, sink) {
             sink.add("error $e");
           },

tests/lib/async/catch_errors17_test.dart

@@ -9,23 +9,23 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
   late StreamController controller;
   // Test that errors do not cross zone boundaries.
   catchErrors(() {
     catchErrors(() {
-      controller = new StreamController();
+      controller = StreamController();
       controller.stream
           .map((x) {
             events.add("map $x");
             return x + 100;
           })
           .transform(
-            new StreamTransformer.fromHandlers(
+            StreamTransformer.fromHandlers(
               handleError: (e, st, sink) {
                 sink.add("error $e");
               },
@@ -39,7 +39,7 @@ main() {
     });
     controller.add(1);
     controller.addError(2);
-    new Future.error("outer error");
+    Future.error("outer error");
     controller.close();
   }).listen(
     (x) {

tests/lib/async/catch_errors18_test.dart

@@ -9,15 +9,12 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
-  Stream stream = new Stream.periodic(
-    const Duration(milliseconds: 20),
-    (x) => x,
-  );
+  Stream stream = Stream.periodic(const Duration(milliseconds: 20), (x) => x);
   // Test that errors of periodic streams are caught.
   catchErrors(() {
     var subscription;

tests/lib/async/catch_errors19_test.dart

@@ -9,15 +9,12 @@ import 'package:expect/expect.dart';
 
 import 'catch_errors.dart';
 
-main() {
+void main() {
   asyncStart();
-  Completer done = new Completer();
+  Completer done = Completer();
 
   var events = [];
-  Stream stream = new Stream.periodic(
-    const Duration(milliseconds: 20),
-    (x) => x,
-  );
+  Stream stream = Stream.periodic(const Duration(milliseconds: 20), (x) => x);
   // Test that asynchronous callbacks in the done-handler of streams (here
   // the `catchErrors`-stream) keep a zone alive.
   catchErrors(() {
@@ -29,7 +26,7 @@ main() {
             events.add(x);
           },
           onDone: () {
-            new Future.delayed(const Duration(milliseconds: 30), () {
+            Future.delayed(const Duration(milliseconds: 30), () {
               events.add(499);
               done.complete(true);
             });