fix(mqtt): birth-typed Sparkplug writes and QoS 1 for Plain writes (#602 STAB-25/26)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
2026-10-08 07:27:42 -04:00
parent e76df0741a
commit 1f4f4fca8f
3 changed files with 90 additions and 11 deletions
@@ -350,6 +350,55 @@ public sealed class MqttWriteEncoderTests
        Payload.Parser.ParseFrom(encoded.Payload).Metrics[0].Name.ShouldBe("Node Control/Rebirth");
    }

+    // ---- STAB-25 / STAB-26 (#602) ---------------------------------------------------------------------
+
+    [Fact]
+    public void A_plain_write_publishes_at_QoS1_so_Good_means_the_broker_accepted_it()
+    {
+        MqttWriteEncoder.TryEncode(MqttMode.Plain, Plain("oven/set"), 42.5, out var encoded)
+            .ShouldBe(MqttWriteEncodeError.None);
+
+        encoded.Qos.ShouldBe(1);
+    }
+
+    [Fact]
+    public void A_sparkplug_command_stays_at_QoS0()
+    {
+        // Pinned beside the Plain case so the two cannot be "unified" by accident: an NCMD/DCMD retry from
+        // QoS 1 redelivery would re-apply a command the device already took.
+        MqttWriteEncoder.TryEncode(MqttMode.SparkplugB, Sparkplug("Filler1"), 1.0, out var encoded)
+            .ShouldBe(MqttWriteEncodeError.None);
+
+        encoded.Qos.ShouldBe(0);
+    }
+
+    [Fact]
+    public void An_unauthored_sparkplug_type_is_commanded_with_the_birth_declared_type()
+    {
+        // DataTypeAuthored=false: the record's Float64 is only a default. The birth said Int32, so the DCMD
+        // must carry Int32 — a Double-typed command to an Int32 metric is the silent-drop shape.
+        var def = Sparkplug("Filler1") with { DataTypeAuthored = false };
+
+        MqttWriteEncoder.TryEncode(MqttMode.SparkplugB, def, 7, out var encoded, DriverDataType.Int32)
+            .ShouldBe(MqttWriteEncodeError.None);
+
+        var metric = Payload.Parser.ParseFrom(encoded.Payload).Metrics[0];
+        metric.Datatype.ShouldBe((uint)TahuDataType.Int32);
+        metric.IntValue.ShouldBe(7u);
+    }
+
+    [Fact]
+    public void An_authored_sparkplug_type_wins_over_the_birth_type()
+    {
+        // Same precedence as the ingest path: authored beats birth.
+        var def = Sparkplug("Filler1", DriverDataType.Float64) with { DataTypeAuthored = true };
+
+        MqttWriteEncoder.TryEncode(MqttMode.SparkplugB, def, 7, out var encoded, DriverDataType.Int32)
+            .ShouldBe(MqttWriteEncodeError.None);
+
+        Payload.Parser.ParseFrom(encoded.Payload).Metrics[0].Datatype.ShouldBe((uint)TahuDataType.Double);
+    }
+
    private static string EncodeTopic(MqttMode mode, MqttTagDefinition def)
    {
        MqttWriteEncoder.TryEncode(mode, def, 1.0, out var encoded).ShouldBe(MqttWriteEncodeError.None);