fix(dcl): MxGateway adapter treats a graceful end of the event stream as a disconnect — a dashboard 'close session' (or graceful gateway shutdown) completes the stream with OK, leaving the adapter Connected on a dead session: values frozen at last GOOD quality, every write 'Session … was not found' until restart (QA vq03 Z28061 MoveIn, 2026-08-20). Pinned: signals once while connected, silent for superseded loops / own teardown

2026-08-20 16:51:13 -04:00
parent f5a74db3de
commit da0bfe2be1
3 changed files with 81 additions and 1 deletions
@@ -1,6 +1,8 @@
+using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
 using Grpc.Core;
 using Microsoft.Extensions.Logging.Abstractions;
 using NSubstitute;
+
 using ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Adapters;

 namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests.Adapters;
@@ -93,6 +95,67 @@ public class MxGatewayDataConnectionReconnectTests
        Assert.Equal(0, Volatile.Read(ref disconnectsRef.Value));
    }

+
+    /// <summary>
+    /// QA incident 2026-08-20 (vq03 Z28061 MoveIn): an operator closed ScadaBridge's session
+    /// from the MxAccess Gateway dashboard. The gateway completes the session's event stream
+    /// GRACEFULLY (<c>CompleteAllSubscribers(error: null)</c>, OK status) — the same path a
+    /// graceful gateway shutdown takes — so <c>RunEventLoopAsync</c> returned normally and the
+    /// adapter never raised <c>Disconnected</c>: values froze at their last GOOD quality and
+    /// every write went to the dead session (<c>Session … was not found</c>) for an hour, until
+    /// a process restart. A non-cancelled end of the event stream IS a disconnect.
+    /// </summary>
+    [Fact]
+    public async Task EventStreamGracefulCompletion_WhileConnected_SignalsDisconnected()
+    {
+        var loops = new List<TaskCompletionSource>();
+        var loopTokens = new List<CancellationToken>();
+        var adapter = CreateAdapterWithControllableLoops(loops, loopTokens, out var disconnectsRef);
+        var details = new Dictionary<string, string> { ["Endpoint"] = "http://gw:5000", ["ApiKey"] = "k" };
+
+        await adapter.ConnectAsync(details);
+        await WaitUntilAsync(() => loopTokens.Count == 1);
+
+        loops[0].SetResult();   // server ended the stream with OK — session closed underneath us
+        await WaitUntilAsync(() => Volatile.Read(ref disconnectsRef.Value) == 1);
+        Assert.Equal(ConnectionHealth.Disconnected, adapter.Status);
+    }
+
+    [Fact]
+    public async Task EventStreamGracefulCompletion_OfSupersededLoop_DoesNotSignalDisconnected()
+    {
+        var loops = new List<TaskCompletionSource>();
+        var loopTokens = new List<CancellationToken>();
+        var adapter = CreateAdapterWithControllableLoops(loops, loopTokens, out var disconnectsRef);
+        var details = new Dictionary<string, string> { ["Endpoint"] = "http://gw:5000", ["ApiKey"] = "k" };
+
+        await adapter.ConnectAsync(details);
+        await WaitUntilAsync(() => loopTokens.Count == 1);
+        await adapter.ConnectAsync(details);          // reconnect: loop #0 is cancelled
+        await WaitUntilAsync(() => loopTokens.Count == 2);
+
+        loops[0].SetResult();   // the OLD loop winds down normally after its cancel
+        await Task.Delay(200);
+        Assert.Equal(0, Volatile.Read(ref disconnectsRef.Value));   // must not flap the new session
+    }
+
+    [Fact]
+    public async Task EventStreamGracefulCompletion_AfterDisconnectAsync_DoesNotSignalDisconnected()
+    {
+        var loops = new List<TaskCompletionSource>();
+        var loopTokens = new List<CancellationToken>();
+        var adapter = CreateAdapterWithControllableLoops(loops, loopTokens, out var disconnectsRef);
+        var details = new Dictionary<string, string> { ["Endpoint"] = "http://gw:5000", ["ApiKey"] = "k" };
+
+        await adapter.ConnectAsync(details);
+        await WaitUntilAsync(() => loopTokens.Count == 1);
+        await adapter.DisconnectAsync();              // our own teardown cancels the loop
+
+        loops[0].SetResult();
+        await Task.Delay(200);
+        Assert.Equal(0, Volatile.Read(ref disconnectsRef.Value));
+    }
+
    private sealed class IntRef { public int Value; }

    private static MxGatewayDataConnection CreateAdapterWithControllableLoops(