add cancellation support to ConnectAsync and corresponding tests

Author: doghappy

src/SocketIOClient/V2/SocketIO.cs

@@ -65,10 +65,16 @@ private Uri ServerUri
     public event EventHandler<Exception> OnReconnectError;
 
     public async Task ConnectAsync()
+    {
+        await ConnectAsync(CancellationToken.None);
+    }
+
+    public async Task ConnectAsync(CancellationToken cancellationToken)
     {
         var attempts = Options.Reconnection ? Options.ReconnectionAttempts : 1;
         for (int i = 0; i < attempts; i++)
         {
+            cancellationToken.ThrowIfCancellationRequested();
             // TODO: IDisposable
             var session = SessionFactory.New(Options.EIO);
             using var cts = new CancellationTokenSource(Options.ConnectionTimeout);

tests/SocketIOClient.UnitTests/V2/SocketIOTests.cs

@@ -127,6 +127,22 @@ public async Task ConnectAsync_ConnectedMessageReceived_ConnectedIsTrueIdHasValu
         _io.Id.Should().Be("123");
     }
 
+    [Fact]
+    public async Task ConnectAsyncCancellationToken_GivenACanceledToken_ThrowConnectionException()
+    {
+        _session.ConnectAsync(Arg.Any<CancellationToken>()).ThrowsAsync(new Exception("Test"));
+
+        await _io
+            .Invoking(async x =>
+            {
+                using var cts = new CancellationTokenSource();
+                await cts.CancelAsync();
+                await x.ConnectAsync(cts.Token);
+            })
+            .Should()
+            .ThrowAsync<OperationCanceledException>();
+    }
+
     [Fact]
     public async Task EmitAsync_AckEventAction_PacketIdIncrementBy1()
     {