feat(s7): expose ReadMultipleVarsAsync through the IS7Plc seam

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7DriverReconnectTests.cs

@@ -569,6 +569,10 @@ public sealed class S7DriverReconnectTests
         public Task<byte[]> ReadBytesAsync(S7NetDataType area, int db, int startByteAdr, int count, CancellationToken cancellationToken) =>
             throw new NotSupportedException("FakeS7Plc: block reads not needed for the reconnect tests");
 
+        public Task<IReadOnlyList<global::S7.Net.Types.DataItem>> ReadMultipleVarsAsync(
+            List<global::S7.Net.Types.DataItem> items, CancellationToken cancellationToken) =>
+            throw new NotSupportedException("FakeS7Plc: multi-var reads not needed for the reconnect tests");
+
         public async Task WriteAsync(string address, object value, CancellationToken cancellationToken)
         {
             if (WriteHangsUntilCancelled)

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7PollEngineMigrationTests.cs

@@ -47,6 +47,10 @@ public sealed class S7PollEngineMigrationTests
             return Task.FromResult(block);
         }
 
+        public Task<IReadOnlyList<global::S7.Net.Types.DataItem>> ReadMultipleVarsAsync(
+            List<global::S7.Net.Types.DataItem> items, CancellationToken ct)
+            => throw new NotSupportedException("ConstantArrayPlc: multi-var reads not needed for the poll-engine tests");
+
         public Task WriteAsync(string address, object value, CancellationToken ct) => Task.CompletedTask;
         public Task WriteBytesAsync(S7NetDataType area, int db, int startByteAdr, byte[] value, CancellationToken ct) => Task.CompletedTask;
         public Task ReadStatusAsync(CancellationToken ct) => Task.CompletedTask;

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7SpanReadParityTests.cs

@@ -323,6 +323,11 @@ public sealed class S7SpanReadParityTests
                 return Task.FromResult(image[startByteAdr..(startByteAdr + count)]);
             }
 
+            /// <inheritdoc />
+            public Task<IReadOnlyList<global::S7.Net.Types.DataItem>> ReadMultipleVarsAsync(
+                List<global::S7.Net.Types.DataItem> items, CancellationToken ct)
+                => throw new NotSupportedException("ImageS7Plc: multi-var reads not served by the parity image fake");
+
             /// <inheritdoc />
             public Task<object?> ReadAsync(string address, CancellationToken ct)
             {

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7TestBuilders.cs

@@ -92,6 +92,10 @@ internal sealed class ConnectingFakeS7PlcFactory : IS7PlcFactory
         public Task<byte[]> ReadBytesAsync(S7NetDataType area, int db, int startByteAdr, int count, CancellationToken ct)
             => throw new NotSupportedException("ConnectingFakeS7Plc serves no data");
         /// <summary>Not exercised by these tests.</summary>
+        public Task<IReadOnlyList<global::S7.Net.Types.DataItem>> ReadMultipleVarsAsync(
+            List<global::S7.Net.Types.DataItem> items, CancellationToken ct)
+            => throw new NotSupportedException("ConnectingFakeS7Plc serves no data");
+        /// <summary>Not exercised by these tests.</summary>
         public Task WriteAsync(string address, object value, CancellationToken ct)
             => throw new NotSupportedException("ConnectingFakeS7Plc serves no data");
         /// <summary>Not exercised by these tests.</summary>