test: add proto contract, cleanup verification, and regression guardrail tests

tests/ScadaLink.Communication.Tests/Grpc/ProtoContractTests.cs

@@ -0,0 +1,79 @@
+using Google.Protobuf.WellKnownTypes;
+using ScadaLink.Communication.Grpc;
+
+namespace ScadaLink.Communication.Tests.Grpc;
+
+/// <summary>
+/// Guardrail tests that verify all oneof variants in SiteStreamEvent have
+/// corresponding conversion handlers. Adding a new proto field without
+/// implementing the conversion will cause these tests to fail.
+/// </summary>
+public class ProtoContractTests
+{
+    /// <summary>
+    /// The set of EventOneofCase values we handle in ConvertToDomainEvent.
+    /// Update this array when adding a new oneof variant.
+    /// </summary>
+    private static readonly SiteStreamEvent.EventOneofCase[] HandledCases =
+    [
+        SiteStreamEvent.EventOneofCase.AttributeChanged,
+        SiteStreamEvent.EventOneofCase.AlarmChanged
+    ];
+
+    [Fact]
+    public void AllOneofVariants_HaveConversionHandlers()
+    {
+        var allCases = System.Enum.GetValues<SiteStreamEvent.EventOneofCase>()
+            .Where(c => c != SiteStreamEvent.EventOneofCase.None)
+            .ToArray();
+
+        Assert.Equal(allCases.Length, HandledCases.Length);
+        foreach (var c in allCases)
+            Assert.Contains(c, HandledCases);
+    }
+
+    [Theory]
+    [InlineData(SiteStreamEvent.EventOneofCase.AttributeChanged)]
+    [InlineData(SiteStreamEvent.EventOneofCase.AlarmChanged)]
+    public void ConvertToDomainEvent_HandlesAllOneofVariants(SiteStreamEvent.EventOneofCase eventCase)
+    {
+        var evt = CreateTestEvent(eventCase);
+        var result = SiteStreamGrpcClient.ConvertToDomainEvent(evt);
+        Assert.NotNull(result);
+    }
+
+    private static SiteStreamEvent CreateTestEvent(SiteStreamEvent.EventOneofCase eventCase)
+    {
+        var ts = Timestamp.FromDateTimeOffset(DateTimeOffset.UtcNow);
+
+        return eventCase switch
+        {
+            SiteStreamEvent.EventOneofCase.AttributeChanged => new SiteStreamEvent
+            {
+                CorrelationId = "test",
+                AttributeChanged = new AttributeValueUpdate
+                {
+                    InstanceUniqueName = "Site1.Inst1",
+                    AttributePath = "Path",
+                    AttributeName = "Attr",
+                    Value = "42",
+                    Quality = Quality.Good,
+                    Timestamp = ts
+                }
+            },
+            SiteStreamEvent.EventOneofCase.AlarmChanged => new SiteStreamEvent
+            {
+                CorrelationId = "test",
+                AlarmChanged = new AlarmStateUpdate
+                {
+                    InstanceUniqueName = "Site1.Inst1",
+                    AlarmName = "HighTemp",
+                    State = AlarmStateEnum.AlarmStateActive,
+                    Priority = 1,
+                    Timestamp = ts
+                }
+            },
+            _ => throw new ArgumentOutOfRangeException(nameof(eventCase), eventCase, "Unhandled event case")
+        };
+    }
+}