fix(siteruntime): decode List value to typed array before DCL write (OPC UA array write path)

tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/RealOpcUaClientArrayWriteTests.cs

@@ -1,20 +1,44 @@
+using System.Collections.Generic;
 using Opc.Ua;
 
 namespace ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests.Adapters;
 
 /// <summary>
-/// MV-8: the OPC UA WRITE path (<see cref="RealOpcUaClient.WriteValueAsync"/>)
-/// wraps the outgoing value in <c>new Variant(value)</c> and lets the OPC
-/// Foundation SDK serialize it. For a structured multi-value (List) attribute
-/// the value handed down is a CLR array. These tests assert that the load-bearing
-/// step — wrapping an array in a <see cref="Variant"/> — succeeds without
-/// throwing, which is what the write path relies on (no separate array handling
-/// is required in our code). A full device round-trip needs a live server and is
-/// covered by the live OPC UA browse/read smoke tests.
+/// SCOPE: these tests cover ONLY the SDK-level building block the write path
+/// relies on — that <c>new Variant(collection)</c> wraps a CLR array / list as a
+/// typed array <see cref="Variant"/> (ValueRank = OneDimension) without throwing.
+/// They are NOT an end-to-end test of the runtime write flow: they feed a
+/// hand-built collection straight into <see cref="Variant"/>, bypassing the
+/// InstanceActor decode step that produces that collection.
+///
+/// The END-TO-END flow — a script's canonical JSON list string being DECODED to a
+/// typed <c>List&lt;T&gt;</c> before the <c>WriteTagRequest</c> reaches the DCL
+/// (so OPC UA writes an array node, not a String scalar) — is covered by
+/// <c>InstanceActorTests.InstanceActor_DataSourcedListWrite_SendsTypedArrayToDcl_NotJsonString</c>.
+/// The runtime hands <see cref="RealOpcUaClient.WriteValueAsync"/> a
+/// <c>List&lt;T&gt;</c> (the codec's decode result), which the SDK wraps
+/// identically to a CLR array — see the <c>List&lt;int&gt;</c> case below. A full
+/// device round-trip needs a live server and is covered by the live OPC UA smoke
+/// tests.
 /// </summary>
 [Trait("Category", "Unit")]
 public class RealOpcUaClientArrayWriteTests
 {
+    [Fact]
+    public void Variant_wraps_int_list_as_array_without_throwing()
+    {
+        // The runtime actually hands WriteValueAsync a List<T> (the decode result),
+        // not a raw T[]; assert the SDK wraps it as a typed array all the same.
+        var value = new List<int> { 10, 20, 30 };
+
+        var ex = Record.Exception(() => new Variant(value));
+
+        Assert.Null(ex);
+        var variant = new Variant(value);
+        Assert.Equal(BuiltInType.Int32, variant.TypeInfo.BuiltInType);
+        Assert.Equal(ValueRanks.OneDimension, variant.TypeInfo.ValueRank);
+    }
+
     [Fact]
     public void Variant_wraps_int_array_without_throwing()
     {