fix(twincat): dispose bit-RMW locks on shutdown + guard null parent read (review)

2026-06-17 12:01:55 -04:00
parent a73e20fb28
commit 340c145e87
2 changed files with 34 additions and 1 deletions
@@ -332,6 +332,24 @@ public sealed class TwinCATReadWriteTests
        factory.Clients[0].WriteLog.ShouldBeEmpty();
    }

+    /// <summary>A Good parent read that yields a null value must NOT zero the word — it surfaces
+    ///     a Bad status and writes nothing (treating null as 0 would clear every set bit).</summary>
+    [Fact]
+    public async Task Bit_write_with_null_parent_value_does_not_zero_the_word()
+    {
+        var (drv, factory) = NewDriver(
+            new TwinCATTagDefinition("Flag", "ads://5.23.91.23.1.1:851", "MAIN.Flags.3", TwinCATDataType.Bool));
+        // Do NOT seed Values["MAIN.Flags"] — the fake returns (null, Good) for the parent read.
+        factory.Customise = () => new FakeTwinCATClient();
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var results = await drv.WriteAsync([new WriteRequest("Flag", true)], CancellationToken.None);
+
+        results.Single().StatusCode.ShouldBe(TwinCATStatusMapper.BadCommunicationError);
+        // No parent write attempted — the word is left untouched on the device.
+        factory.Clients[0].WriteLog.ShouldBeEmpty();
+    }
+
    /// <summary>Concurrent bit writes to the same word compose correctly (per-parent lock).</summary>
    [Fact]
    public async Task Concurrent_bit_writes_to_same_word_compose_correctly()