fix(dcl): treat OPC UA BadResourceUnavailable as transient Bad; Bad+null keeps last-known value (ScadaBridge#112)

OtOpcUa's out-of-process script runner publishes 0x80040000 with a null value. - OpcUaDataConnection: logs entry/recovery once per tag, names the symbolic status in read errors; never a disconnect (not in the reconnect status set). - InstanceActor: a Bad update with no value is a quality-only transition (keep value, quality Bad, stream publish, no script/alarm/waiter re-eval), matching the connection-drop rule. Bad with a value is unchanged. Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
2026-11-10 04:38:05 -05:00
parent 533414a16d
commit 08fe5acfe4
5 changed files with 322 additions and 2 deletions
@@ -768,6 +768,92 @@ public class InstanceActorTests : TestKit, IDisposable
        Assert.Equal(1450, response.Value);
    }

+    /// <summary>
+    /// ScadaBridge#112: a Bad-quality update that carries NO value (OtOpcUa sends a null Value
+    /// with every Bad status, e.g. BadResourceUnavailable from its out-of-process script runner)
+    /// is a quality-only transition — the last-known value survives, quality goes Bad, waiters
+    /// and children are not re-evaluated against a null that never existed, and the next Good
+    /// update recovers the attribute. Pins the Good / Bad(null) / Good sequence.
+    /// </summary>
+    [Fact]
+    public void InstanceActor_BadQualityWithNullValue_KeepsLastKnownValue_AndRecoversOnGood()
+    {
+        const string tag = "nsu=https://zb.com/otopcua/uns;s=Line1.Pump.Calc";
+        var config = new FlattenedConfiguration
+        {
+            InstanceUniqueName = "Pump-BadNull",
+            Attributes =
+            [
+                new ResolvedAttribute
+                {
+                    CanonicalName = "Calc", Value = "0", DataType = "Int32",
+                    DataSourceReference = tag, BoundDataConnectionName = "OtOpcUa"
+                }
+            ]
+        };
+
+        var dcl = CreateTestProbe();
+        var actor = CreateInstanceActorWithDcl("Pump-BadNull", config, dcl);
+
+        actor.Tell(new TagValueUpdate("OtOpcUa", tag, 1450, QualityCode.Good, DateTimeOffset.UtcNow));
+
+        // A waiter that would fire if the stored value were ever nulled.
+        actor.Tell(new WaitForAttributeRequest(
+            "wfa-null", "Pump-BadNull", "Calc",
+            null, v => v is null, TimeSpan.FromSeconds(30), DateTimeOffset.UtcNow));
+        ExpectNoMsg(TimeSpan.FromMilliseconds(200));
+
+        // Source goes BadResourceUnavailable: Bad quality, null value.
+        actor.Tell(new TagValueUpdate("OtOpcUa", tag, null, QualityCode.Bad, DateTimeOffset.UtcNow));
+        ExpectNoMsg(TimeSpan.FromMilliseconds(300));
+
+        actor.Tell(new GetAttributeRequest("corr-bad", "Pump-BadNull", "Calc", DateTimeOffset.UtcNow));
+        var bad = ExpectMsg<GetAttributeResponse>(TimeSpan.FromSeconds(5));
+        Assert.True(bad.Found);
+        Assert.Equal("Bad", bad.Quality);
+        Assert.Equal(1450, bad.Value);
+
+        // Next good evaluation recovers.
+        actor.Tell(new TagValueUpdate("OtOpcUa", tag, 1500, QualityCode.Good, DateTimeOffset.UtcNow));
+        actor.Tell(new GetAttributeRequest("corr-good", "Pump-BadNull", "Calc", DateTimeOffset.UtcNow));
+        var good = ExpectMsg<GetAttributeResponse>(TimeSpan.FromSeconds(5));
+        Assert.Equal("Good", good.Quality);
+        Assert.Equal(1500, good.Value);
+    }
+
+    /// <summary>
+    /// Guard for ScadaBridge#112: a Bad update that DOES carry a value keeps the historical
+    /// behaviour — the carried value is stored with Bad quality.
+    /// </summary>
+    [Fact]
+    public void InstanceActor_BadQualityWithValue_StoresCarriedValue()
+    {
+        const string tag = "ns=3;s=Pump.BadWithValue";
+        var config = new FlattenedConfiguration
+        {
+            InstanceUniqueName = "Pump-BadValue",
+            Attributes =
+            [
+                new ResolvedAttribute
+                {
+                    CanonicalName = "Speed", Value = "0", DataType = "Int32",
+                    DataSourceReference = tag, BoundDataConnectionName = "PLC"
+                }
+            ]
+        };
+
+        var dcl = CreateTestProbe();
+        var actor = CreateInstanceActorWithDcl("Pump-BadValue", config, dcl);
+
+        actor.Tell(new TagValueUpdate("PLC", tag, 1450, QualityCode.Good, DateTimeOffset.UtcNow));
+        actor.Tell(new TagValueUpdate("PLC", tag, 1300, QualityCode.Bad, DateTimeOffset.UtcNow));
+
+        actor.Tell(new GetAttributeRequest("corr-bv", "Pump-BadValue", "Speed", DateTimeOffset.UtcNow));
+        var response = ExpectMsg<GetAttributeResponse>(TimeSpan.FromSeconds(5));
+        Assert.Equal("Bad", response.Quality);
+        Assert.Equal(1300, response.Value);
+    }
+
    /// <summary>
    /// MV (C1 fix): a WRITE to a data-sourced <c>DataType.List</c> attribute must
    /// send the DCL a TYPED collection (so OPC UA writes an array node), NOT the