co19/LibTest/io/WebSocket/closeCode_A01_t02 is racy, fails on Windows

[aam]

The test fails on Windows, seemingly due to a race between client attempting to close the connection and server done its part closing.

Following fixes the test:

diff --git a/LibTest/io/WebSocket/closeCode_A01_t02.dart b/LibTest/io/WebSocket/closeCode_A01_t02.dart
index 85ef48c6a2..31f0b4d03c 100644
--- a/LibTest/io/WebSocket/closeCode_A01_t02.dart
+++ b/LibTest/io/WebSocket/closeCode_A01_t02.dart
@@ -10,23 +10,27 @@
 /// closed.
 /// @author ngl@unipro.ru

+import "dart:async";
 import "dart:io";
 import "../../../Utils/expect.dart";

 main() {
+  final serverIsClosed = Completer<bool>();
   HttpServer.bind("127.0.0.1", 0).then((server) {
     server.listen((request) {
       WebSocketTransformer
           .upgrade(request)
           .then((websocket) {
-        websocket.close(WebSocketStatus.normalClosure);
+        websocket.close(WebSocketStatus.normalClosure).then((_) {
+          serverIsClosed.complete(true);
+        });
       });
     });

     var webs = WebSocket.connect("ws://127.0.0.1:${server.port}/");
     webs.then((client) async {
       Expect.isNull(client.closeCode);
-      await server.close();
+      server.close();
+      await serverIsClosed.future;
       client.close().then((_) {
         Expect.equals(WebSocketStatus.normalClosure, client.closeCode);
       });

[sgrekhov]

With the fix applied the test is still racy. I'll dig into it