Update 'samples/sample_extension' to Dart 2

- Ran `dartfmt --fix`
- Fixed Dart 2 type errors
- Other misc cleanup (to conform to Effective Dart)

Contributes to https://github.com/dart-lang/site-www/issues/980

cc @a-siva @kwalrath @kevmoo

Closes #33711
https://github.com/dart-lang/sdk/pull/33711

GitOrigin-RevId: a832220272fe50a8bd96c6bc71692d54dcbf9465
Change-Id: Ia542ce073d2f9a4c78934a74ee17b60156a49d25
Reviewed-on: https://dart-review.googlesource.com/c/63260
Commit-Queue: Kathy Walrath <kathyw@google.com>
Reviewed-by: Kathy Walrath <kathyw@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

samples/sample_extension/sample_asynchronous_extension.dart

@@ -13,30 +13,25 @@ class RandomArray {
   static SendPort _port;
 
   Future<List<int>> randomArray(int seed, int length) {
-    var completer = new Completer();
-    var replyPort = new RawReceivePort();
-    var args = new List(3);
+    var completer = Completer<List<int>>();
+    var replyPort = RawReceivePort();
+    var args = List<Object>(3);
     args[0] = seed;
     args[1] = length;
     args[2] = replyPort.sendPort;
     _servicePort.send(args);
-    replyPort.handler = (result) {
+    replyPort.handler = (List<int> result) {
       replyPort.close();
       if (result != null) {
         completer.complete(result);
       } else {
-        completer.completeError(new Exception("Random array creation failed"));
+        completer.completeError(Exception('Random array creation failed'));
       }
     };
     return completer.future;
   }
 
-  SendPort get _servicePort {
-    if (_port == null) {
-      _port = _newServicePort();
-    }
-    return _port;
-  }
+  SendPort get _servicePort => _port ??= _newServicePort();
 
-  SendPort _newServicePort() native "RandomArray_ServicePort";
+  SendPort _newServicePort() native 'RandomArray_ServicePort';
 }

samples/sample_extension/sample_synchronous_extension.dart

@@ -7,6 +7,6 @@ library sample_synchronous_extension;
 import 'dart-ext:sample_extension';
 
 // The simplest way to call native code: top-level functions.
-int systemRand() native "SystemRand";
-int noScopeSystemRand() native "NoScopeSystemRand";
-bool systemSrand(int seed) native "SystemSrand";
+int systemRand() native 'SystemRand';
+int noScopeSystemRand() native 'NoScopeSystemRand';
+bool systemSrand(int seed) native 'SystemSrand';

samples/sample_extension/test/sample_extension_test_helper.dart

@@ -6,7 +6,6 @@
 
 import 'dart:async';
 import 'dart:io';
-import 'dart:isolate';
 
 import "package:expect/expect.dart";
 import "package:path/path.dart";
@@ -45,7 +44,6 @@ Future run(String program, List<String> arguments) async {
 }
 
 Future testNativeExtensions(String snapshotKind) async {
-  String buildDirectory = dirname(Platform.executable);
   Directory tempDirectory =
       Directory.systemTemp.createTempSync('sample_extension_');
   try {
@@ -73,14 +71,14 @@ Future testNativeExtensions(String snapshotKind) async {
         snapshot = script;
       } else {
         snapshot = join(testDirectory, "$test.snapshot");
-        List<String> args = new List<String>.from(Platform.executableArguments);
+        List<String> args = List<String>.from(Platform.executableArguments);
         args.add('--snapshot=$snapshot');
         args.add('--snapshot-kind=$snapshotKind');
         args.add(script);
         await run(Platform.executable, args);
       }
 
-      List<String> args = new List<String>.from(Platform.executableArguments);
+      List<String> args = List<String>.from(Platform.executableArguments);
       args.add(snapshot);
       await run(Platform.executable, args);
     }

samples/sample_extension/test_sample_asynchronous_extension.dart

@@ -7,17 +7,15 @@ library test_sample_extension;
 import 'sample_asynchronous_extension.dart';
 
 void check(bool condition, String message) {
-  if (!condition) {
-    throw new StateError(message);
-  }
+  if (!condition) throw StateError(message);
 }
 
 void main() {
-  RandomArray r = new RandomArray();
+  RandomArray r = RandomArray();
   r.randomArray(17, 100).then((list_100) {
     r.randomArray(17, 200).then((list_200) {
       for (var i = 0; i < 100; ++i) {
-        check(list_100[i] == list_200[i], "list_100[i] == list_200[i]");
+        check(list_100[i] == list_200[i], 'list_100[i] == list_200[i]');
       }
     });
   });
@@ -27,32 +25,26 @@ void main() {
   r.randomArray(19, 256000).then(checkNormal);
 }
 
-void checkNormal(List l) {
+void checkNormal(List<int> l) {
   // Count how many times each byte value occurs.  Assert that the counts
   // are all within a reasonable (six-sigma) range.
-  List counts = new List<int>.filled(256, 0);
-  for (var e in l) {
-    counts[e]++;
-  }
-  new RandomArray().randomArray(18, 256000).then(checkCorrelation(counts));
+  final counts = List<int>.filled(256, 0);
+  for (var e in l) counts[e]++;
+  RandomArray().randomArray(18, 256000).then(checkCorrelation(counts));
 }
 
-Function checkCorrelation(List counts) {
-  return (List l) {
-    List counts_2 = new List<int>.filled(256, 0);
-    for (var e in l) {
-      counts_2[e]++;
-    }
-    var product = 0;
-    for (var i = 0; i < 256; ++i) {
-      check(counts[i] < 1200, "counts[i] < 1200");
-      check(counts_2[i] < 1200, "counts_2[i] < 1200");
-      check(counts[i] > 800, "counts[i] > 800");
-      check(counts[i] > 800, "counts[i] > 800");
+void Function(List<int>) checkCorrelation(List<int> counts) => (l) {
+      final counts_2 = List<int>.filled(256, 0);
+      for (var e in l) counts_2[e]++;
+      var product = 0;
+      for (var i = 0; i < 256; ++i) {
+        check(counts[i] < 1200, 'counts[i] < 1200');
+        check(counts_2[i] < 1200, 'counts_2[i] < 1200');
+        check(counts[i] > 800, 'counts[i] > 800');
+        check(counts[i] > 800, 'counts[i] > 800');
 
-      product += counts[i] * counts_2[i];
-    }
-    check(product < 256000000 * 1.001, "product < 256000000 * 1.001");
-    check(product > 256000000 * 0.999, "product > 256000000 * 0.999");
-  };
-}
+        product += counts[i] * counts_2[i];
+      }
+      check(product < 256000000 * 1.001, 'product < 256000000 * 1.001');
+      check(product > 256000000 * 0.999, 'product > 256000000 * 0.999');
+    };

samples/sample_extension/test_sample_synchronous_extension.dart

@@ -7,9 +7,8 @@ library test_sample_extension;
 import 'sample_synchronous_extension.dart';
 
 void check(bool condition, String message) {
-  if (!condition) {
-    throw new StateError(message);
-  }
+  if (!condition) throw StateError(message);
+  print('$message - passed');
 }
 
 void checkSystemRand() {
@@ -17,17 +16,17 @@ void checkSystemRand() {
   var x1 = systemRand();
   var x2 = systemRand();
   var x3 = systemRand();
-  check(x1 != x2, "x1 != x2");
-  check(x1 != x3, "x1 != x3");
-  check(x2 != x3, "x2 != x3");
+  check(x1 != x2, 'x1 != x2');
+  check(x1 != x3, 'x1 != x3');
+  check(x2 != x3, 'x2 != x3');
   systemSrand(17);
-  check(x1 == systemRand(), "x1 == systemRand()");
-  check(x2 == systemRand(), "x2 == systemRand()");
-  check(x3 == systemRand(), "x3 == systemRand()");
+  check(x1 == systemRand(), 'x1 == systemRand()');
+  check(x2 == systemRand(), 'x2 == systemRand()');
+  check(x3 == systemRand(), 'x3 == systemRand()');
   systemSrand(18);
-  check(x1 != systemRand(), "x1 != systemRand()");
-  check(x2 != systemRand(), "x2 != systemRand()");
-  check(x3 != systemRand(), "x3 != systemRand()");
+  check(x1 != systemRand(), 'x1 != systemRand()');
+  check(x2 != systemRand(), 'x2 != systemRand()');
+  check(x3 != systemRand(), 'x3 != systemRand()');
 }
 
 void checkNoScopeSystemRand() {
@@ -35,17 +34,17 @@ void checkNoScopeSystemRand() {
   var x1 = noScopeSystemRand();
   var x2 = noScopeSystemRand();
   var x3 = noScopeSystemRand();
-  check(x1 != x2, "x1 != x2");
-  check(x1 != x3, "x1 != x3");
-  check(x2 != x3, "x2 != x3");
+  check(x1 != x2, 'x1 != x2');
+  check(x1 != x3, 'x1 != x3');
+  check(x2 != x3, 'x2 != x3');
   systemSrand(17);
-  check(x1 == noScopeSystemRand(), "x1 == noScopeSystemRand()");
-  check(x2 == noScopeSystemRand(), "x2 == noScopeSystemRand()");
-  check(x3 == noScopeSystemRand(), "x3 == noScopeSystemRand()");
+  check(x1 == noScopeSystemRand(), 'x1 == noScopeSystemRand()');
+  check(x2 == noScopeSystemRand(), 'x2 == noScopeSystemRand()');
+  check(x3 == noScopeSystemRand(), 'x3 == noScopeSystemRand()');
   systemSrand(18);
-  check(x1 != noScopeSystemRand(), "x1 != noScopeSystemRand()");
-  check(x2 != noScopeSystemRand(), "x2 != noScopeSystemRand()");
-  check(x3 != noScopeSystemRand(), "x3 != noScopeSystemRand()");
+  check(x1 != noScopeSystemRand(), 'x1 != noScopeSystemRand()');
+  check(x2 != noScopeSystemRand(), 'x2 != noScopeSystemRand()');
+  check(x3 != noScopeSystemRand(), 'x3 != noScopeSystemRand()');
 }
 
 void main() {

samples/samples.status

@@ -26,10 +26,13 @@ sample_extension/test/sample_extension_app_snapshot_test: Pass, RuntimeError # I
 [ !$preview_dart_2 && ($runtime == dart_precompiled || $runtime == vm) ]
 *: SkipByDesign # Deprecating all Dart1 modes of execution
 
-[ $compiler == app_jitk || $compiler == dartk || $compiler == dartkb || $compiler == dartkp ]
+[ $compiler == app_jitk || $compiler == dartkb || $compiler == dartkp ]
 sample_extension/test/sample_extension_app_snapshot_test: RuntimeError
 sample_extension/test/sample_extension_test: RuntimeError
 
+[ $compiler == dartk ]
+sample_extension/test/sample_extension_app_snapshot_test: RuntimeError
+
 # Skip tests that use dart:io
 [ $runtime == d8 || $browser ]
 sample_extension/*: Skip