fix(historian): #690 Gateway raw/AtTime Bad rows carry no value (a stored NULL was value 0)

2026-10-12 16:08:54 -04:00
parent 1f5d310071
commit 39552e15b9
6 changed files with 68 additions and 4 deletions
@@ -111,6 +111,21 @@ public sealed class GatewayHistorianDataSourceTests
        Assert.Equal(0x80000000u, r.Samples[1].StatusCode); // gap → Bad at requested ts
    }

+    [Fact] // #690: an at-time NULL (histsdk: value 0 + Bad) is null + Bad, like the SQL backends' AtTime of a Bad sample
+    public async Task ReadAtTime_of_a_NULL_row_carries_no_value()
+    {
+        var fake = new FakeHistorianGatewayClient();
+        var t0 = new DateTime(2026, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        fake.AtTimeSamples = new[]
+        {
+            new HistorianSample { NumericValue = 0, OpcQuality = 0, Quality = 1, Timestamp = Timestamp.FromDateTime(t0) },
+        };
+        var ds = new GatewayHistorianDataSource(fake, NullLogger<GatewayHistorianDataSource>.Instance);
+        var r = await ds.ReadAtTimeAsync("T", new[] { t0 }, TestContext.Current.CancellationToken);
+        Assert.Null(r.Samples[0].Value);
+        Assert.Equal(0x80000000u, r.Samples[0].StatusCode);
+    }
+
    [Fact]
    public async Task Empty_window_is_not_a_fault()
    {
@@ -109,6 +109,15 @@ public sealed class GatewayRawBoundaryRowTests
        r.Samples[0].StatusCode.ShouldBe(0x80000000u);
    }

+    [Fact] // #690: the wire's value 0 on a NULL row is not a value — SqlServer/QuestDB return null + Bad for the same sample
+    public async Task A_stored_NULL_sample_carries_no_value_not_the_wires_zero()
+    {
+        var r = await Source(Gate()).ReadRawAsync("T", At(30), At(55), 0, Ct);
+        r.Samples[0].SourceTimestampUtc.ShouldBe(At(40));
+        r.Samples[0].Value.ShouldBeNull();
+        r.Samples[1].Value.ShouldBe(5d); // a Good neighbour keeps its value
+    }
+
    [Fact]
    public async Task A_stored_sample_exactly_at_the_window_start_is_kept()
    {
@@ -32,6 +32,31 @@ public sealed class SampleMapperTests
        Assert.Equal(0x80000000u, SampleMapper.ToSnapshot(s).StatusCode);
    }

+    [Theory] // #690: histsdk puts a value on every row, so a NULL row arrives as 0 / "" with a Bad quality
+    [InlineData(0u, 1u)]   // the live NULL row: opc_quality 0, AVEVA quality 1
+    [InlineData(24u, 0u)]  // any Bad OPC quality (out of service)
+    public void A_Bad_numeric_row_carries_no_value(uint opc, uint quality)
+    {
+        var s = new HistorianSample { Tag = "T", NumericValue = 0, OpcQuality = opc, Quality = quality, Timestamp = Ts(2026, 1, 1, 0, 0, 0) };
+        var snap = SampleMapper.ToSnapshot(s);
+        Assert.True(snap.StatusCode >= 0x80000000u);
+        Assert.Null(snap.Value);
+    }
+
+    [Fact] // #690: a string tag's NULL row arrives as "" + Bad
+    public void A_Bad_string_row_carries_no_value()
+    {
+        var s = new HistorianSample { Tag = "T", StringValue = "", OpcQuality = 0, Quality = 1, Timestamp = Ts(2026, 1, 1, 0, 0, 0) };
+        Assert.Null(SampleMapper.ToSnapshot(s).Value);
+    }
+
+    [Fact] // #690: an Uncertain row keeps its value (only Bad means "no value")
+    public void An_Uncertain_row_keeps_its_value()
+    {
+        var s = new HistorianSample { Tag = "T", NumericValue = 3, OpcQuality = 64, Timestamp = Ts(2026, 1, 1, 0, 0, 0) };
+        Assert.Equal(3d, SampleMapper.ToSnapshot(s).Value);
+    }
+
    [Fact]
    public void Aggregate_null_value_is_BadNoData()
    {