fix(historian): SQL quality contract, long-name refusal, info-bit masking, AtTime-after-now, bootstrap hardening

- I-1: an Empty sample is always Bad. The writer stores a non-Bad NaN/Inf as Empty+BadOutOfRange and any other non-Bad Empty as BadNoData; the updater refuses a non-Bad Empty with BadInvalidArgument; reads clamp a legacy non-Bad Empty row to BadNoData (Raw and AtTime). - Tag/source names over 400 chars are refused, never truncated: writer per-tag failure, updater BadInvalidArgument, reads not-found, events none. - HistorianInfoBits masks the historian bits before setting one. - AtTime past now, stepped from the last sample => UncertainDataSubNormal. - Bootstrapper: logger, 5 s negative cache, ClearPool + Warning when sp_releaseapplock fails. - Provider builds its shared state lazily (an invalid Schema no longer throws at Resolve); Kinds is a FrozenSet; Gateway reuses the recorder's DefaultSupportedKinds. - Cleanup: SqlHistorianDataTypes in its own file (updater dup removed), dead Invalidate and unused status consts deleted, named severity masks, alarm writer brace. Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
2026-10-09 14:16:31 -04:00
parent fc57eefca6
commit 821763a09d
20 changed files with 611 additions and 126 deletions
@@ -116,6 +116,19 @@ public sealed class AtTimeReadTests(SqlHistorianFixture fx)
        s.StatusCode.ShouldBe(GoodInterpolated);
    }

+    [Fact]
+    public async Task A_time_after_now_stepped_from_the_last_sample_is_uncertain()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        await db.SeedAAsync(); // last sample +40 = 50, Good
+        var src = db.Source(new FixedClock(new DateTimeOffset(At(42))));
+        var s = (await src.ReadAtTimeAsync("A", [At(41), At(45)], Ct)).Samples;
+        s[0].Value.ShouldBe(50d);
+        s[0].StatusCode.ShouldBe(GoodInterpolated);       // after the last sample but not after now: held Good
+        s[1].Value.ShouldBe(50d);
+        s[1].StatusCode.ShouldBe(UncertainInterpolated);  // after now: the value is not known to still hold
+    }
+
    [Fact]
    public async Task An_uncertain_neighbour_makes_the_interpolation_uncertain()
    {
@@ -0,0 +1,9 @@
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+/// <summary>A settable clock for the data source's "now" and the bootstrapper's failure cache.</summary>
+internal sealed class FixedClock(DateTimeOffset now) : TimeProvider
+{
+    public DateTimeOffset Now { get; set; } = now;
+
+    public override DateTimeOffset GetUtcNow() => Now;
+}
@@ -0,0 +1,87 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+/// <summary>
+///     Names longer than the 400-character <c>Tag.Name</c> / <c>Event.SourceName</c> columns are refused, never
+///     truncated. Each test seeds a series under the 400-character PREFIX of the long name: a sized
+///     <c>NVarChar(400)</c> parameter would silently cut the long name to that prefix and hit the wrong series.
+/// </summary>
+[Collection(SqlHistorianCollection.Name)]
+public sealed class LongNameTests(SqlHistorianFixture fx)
+{
+    private static readonly CancellationToken Ct = CancellationToken.None;
+    private static DateTime At(double s) => ReadTestDb.At(s);
+
+    private const uint BadInvalidArgument = 0x80AB0000u;
+    private const uint BadNoData = 0x809B0000u;
+
+    private static readonly string Prefix = new('p', 400);
+    private static readonly string Long = Prefix + "-x";
+
+    [Fact]
+    public async Task The_writer_refuses_a_long_name_as_a_per_tag_failure_and_writes_nothing()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        await db.SeedAsync(Prefix, (At(0), HistorianValue.FromDouble(1), ReadTestDb.Good));
+        var w = new SqlServerHistorianValueWriter(db.Conn, db.Boot, new SqlServerTagCatalog(db.Conn, db.Boot));
+
+        (await w.WriteLiveValuesAsync(Long, [new(At(5), HistorianValue.FromDouble(2), 0u)], Ct)).ShouldBeFalse();
+
+        (await db.ScalarAsync($"SELECT COUNT(*) FROM {db.Conn.Q("Sample")}")).ShouldBe(1);
+        (await db.ScalarAsync($"SELECT COUNT(*) FROM {db.Conn.Q("Tag")}")).ShouldBe(1);
+    }
+
+    [Fact]
+    public async Task The_updater_answers_BadInvalidArgument_for_every_item_of_a_long_name()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        await db.SeedAsync(Prefix, (At(0), HistorianValue.FromDouble(1), ReadTestDb.Good));
+        var u = new SqlServerHistorianDataUpdater(db.Conn, new SqlServerTagCatalog(db.Conn, db.Boot));
+
+        (await u.UpdateDataAsync(Long, HistoryUpdateMode.Update,
+            [new(At(0), HistorianValue.FromDouble(9), 0u), new(At(1), HistorianValue.FromDouble(9), 0u)], Ct))
+            .ShouldBe([BadInvalidArgument, BadInvalidArgument]);
+        (await u.DeleteRawAsync(Long, At(-1), At(10), Ct)).ShouldBe(BadInvalidArgument);
+        (await u.DeleteAtTimeAsync(Long, [At(0)], Ct)).ShouldBe([BadInvalidArgument]);
+
+        // The prefix series is untouched: not replaced, not deleted.
+        var raw = (await db.Source().ReadRawAsync(Prefix, At(-1), At(10), 0, Ct)).Samples;
+        raw.Select(s => s.Value).ShouldBe([(object)1d]);
+    }
+
+    [Fact]
+    public async Task Reads_of_a_long_name_are_not_found_rather_than_the_prefix_series()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        await db.SeedAsync(Prefix, (At(0), HistorianValue.FromDouble(1), ReadTestDb.Good));
+        var src = db.Source();
+
+        (await src.ReadRawAsync(Long, At(-1), At(10), 0, Ct)).Samples.ShouldBeEmpty();
+        (await src.ReadAtTimeAsync(Long, [At(0)], Ct)).Samples.Single().StatusCode.ShouldBe(BadNoData);
+        (await src.ReadProcessedAsync(Long, At(-1), At(10), TimeSpan.Zero, HistoryAggregateType.Count, Ct))
+            .Samples.Single().StatusCode.ShouldBe(HistorianInfoBits.WithCalculated(BadNoData));
+        src.GetHealthSnapshot().TotalFailures.ShouldBe(0);
+    }
+
+    [Fact]
+    public async Task An_event_read_filtered_by_a_long_source_matches_nothing()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        await using (var c = await db.Conn.OpenAsync(Ct))
+        await using (var cmd = db.Conn.CreateCommand(c,
+            $"INSERT {db.Conn.Q("Event")} (EventId, SourceName, AlarmId, AlarmName, AlarmTypeName, Severity, EventKind, Message, " +
+            "UserName, Comment, EventTimeUtc, ReceivedTimeUtc) VALUES ('e1', @src, 'a', 'n', 'T', 500, 'Activated', NULL, NULL, NULL, @t, @t)"))
+        {
+            cmd.Parameters.AddWithValue("@src", Prefix);
+            SqlHistorianConnection.AddDateTime2(cmd, "@t", At(0));
+            await cmd.ExecuteNonQueryAsync(Ct);
+        }
+
+        var src = db.Source();
+        (await src.ReadEventsAsync(Prefix, At(-1), At(10), 0, Ct)).Events.Count.ShouldBe(1); // control
+        (await src.ReadEventsAsync(Long, At(-1), At(10), 0, Ct)).Events.ShouldBeEmpty();
+    }
+}
@@ -0,0 +1,104 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+/// <summary>
+///     Final-review I-1: a stored sample is never served with a better quality than "no value". An Empty (null-value)
+///     sample is always Bad — forced Bad by the value writer, refused non-Bad by the updater, and clamped to
+///     <c>BadNoData</c> on read for rows written before either rule existed.
+/// </summary>
+[Collection(SqlHistorianCollection.Name)]
+public sealed class QualityContractTests(SqlHistorianFixture fx)
+{
+    private static readonly CancellationToken Ct = CancellationToken.None;
+    private static DateTime At(double s) => ReadTestDb.At(s);
+
+    private const uint BadOutOfRange = 0x803C0000u;
+    private const uint BadNoData = 0x809B0000u;
+    private const uint BadInvalidArgument = 0x80AB0000u;
+    private const uint BadNoCommunication = 0x80310000u;
+
+    private static bool IsBad(uint status) => (status & 0x80000000u) != 0;
+
+    private static SqlServerHistorianValueWriter Writer(ReadTestDb db) =>
+        new(db.Conn, db.Boot, new SqlServerTagCatalog(db.Conn, db.Boot));
+
+    private static SqlServerHistorianDataUpdater Updater(ReadTestDb db) =>
+        new(db.Conn, new SqlServerTagCatalog(db.Conn, db.Boot));
+
+    [Fact]
+    public async Task A_good_NaN_written_through_the_real_writer_reads_back_Bad_on_Raw_and_AtTime()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        (await Writer(db).WriteLiveValuesAsync("nan", [
+            new(At(0), HistorianValue.FromDouble(10), 0u),
+            new(At(10), HistorianValue.FromDouble(double.NaN), 0u),
+            new(At(20), HistorianValue.FromDouble(double.PositiveInfinity), 0x40000000u),
+            new(At(30), HistorianValue.FromDouble(double.NegativeInfinity), BadNoCommunication),
+        ], Ct)).ShouldBeTrue();
+
+        var raw = (await db.Source().ReadRawAsync("nan", At(0), At(100), 0, Ct)).Samples;
+        raw.Count.ShouldBe(4);
+        raw[1].Value.ShouldBeNull();
+        raw[1].StatusCode.ShouldBe(BadOutOfRange);   // Good NaN ⇒ stored Bad
+        raw[2].StatusCode.ShouldBe(BadOutOfRange);   // Uncertain +Inf ⇒ stored Bad
+        raw[3].StatusCode.ShouldBe(BadNoCommunication); // an existing Bad code is kept
+
+        var at = (await db.Source().ReadAtTimeAsync("nan", [At(10), At(15)], Ct)).Samples;
+        at.ShouldAllBe(s => s.Value == null);
+        at.ShouldAllBe(s => IsBad(s.StatusCode));
+        at[1].StatusCode.ShouldBe(BadOutOfRange);    // inside the "outage" the NaN opened
+    }
+
+    [Fact]
+    public async Task A_non_bad_Empty_written_through_the_real_writer_is_stored_BadNoData()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        (await Writer(db).WriteLiveValuesAsync("empty", [
+            new(At(0), HistorianValue.Empty, 0u),
+            new(At(1), HistorianValue.Empty, 0x40000000u),
+            new(At(2), HistorianValue.Empty, BadNoCommunication),
+        ], Ct)).ShouldBeTrue();
+
+        // Read the stored column directly so the read-side clamp cannot mask a writer that forgot to force Bad.
+        (await db.ScalarAsync($"SELECT COUNT(*) FROM {db.Conn.Q("Sample")} WHERE StatusCode >= 0")).ShouldBe(0);
+        var raw = (await db.Source().ReadRawAsync("empty", At(0), At(10), 0, Ct)).Samples;
+        raw.Select(s => s.StatusCode).ShouldBe([BadNoData, BadNoData, BadNoCommunication]);
+    }
+
+    [Fact]
+    public async Task A_legacy_good_Empty_row_is_clamped_to_BadNoData_on_Raw_and_AtTime()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        // Seeded with plain INSERTs, bypassing the writer: what a pre-fix build could have stored.
+        await db.SeedAsync("legacy",
+            (At(0), HistorianValue.FromDouble(10), ReadTestDb.Good),
+            (At(10), HistorianValue.Empty, ReadTestDb.Good),
+            (At(20), HistorianValue.Empty, ReadTestDb.Uncertain),
+            (At(30), HistorianValue.FromDouble(40), ReadTestDb.Good));
+
+        var raw = (await db.Source().ReadRawAsync("legacy", At(0), At(100), 0, Ct)).Samples;
+        raw.Select(s => s.StatusCode).ShouldBe([ReadTestDb.Good, BadNoData, BadNoData, ReadTestDb.Good]);
+
+        var at = (await db.Source().ReadAtTimeAsync("legacy", [At(10), At(15), At(25)], Ct)).Samples;
+        at.ShouldAllBe(s => s.Value == null && s.StatusCode == BadNoData);
+    }
+
+    [Fact]
+    public async Task The_updater_refuses_a_non_bad_Empty_and_accepts_a_bad_one()
+    {
+        var db = await ReadTestDb.CreateAsync(fx);
+        var r = await Updater(db).UpdateDataAsync("u", HistoryUpdateMode.Insert, [
+            new(At(0), HistorianValue.Empty, 0u),
+            new(At(1), HistorianValue.Empty, 0x40000000u),
+            new(At(2), HistorianValue.Empty, BadNoCommunication),
+            new(At(3), HistorianValue.FromDouble(1), 0u),
+        ], Ct);
+        r.ShouldBe([BadInvalidArgument, BadInvalidArgument, SqlHistorianStatusCodes.GoodEntryInserted,
+            SqlHistorianStatusCodes.GoodEntryInserted]);
+        (await db.Source().ReadRawAsync("u", At(0), At(10), 0, Ct)).Samples
+            .Select(s => s.StatusCode).ShouldBe([BadNoCommunication, 0u]);
+    }
+}
@@ -42,8 +42,9 @@ internal sealed class ReadTestDb
        return new ReadTestDb(o, conn, boot);
    }

-    /// <summary>A fresh data source (fresh catalog cache) over this schema.</summary>
-    public SqlServerHistorianDataSource Source() => new(Conn, Boot, new SqlServerTagCatalog(Conn, Boot));
+    /// <summary>A fresh data source (fresh catalog cache) over this schema; <paramref name="clock"/> is its "now".</summary>
+    public SqlServerHistorianDataSource Source(TimeProvider? clock = null) =>
+        new(Conn, Boot, new SqlServerTagCatalog(Conn, Boot), timeProvider: clock);

    /// <summary>Inserts a tag row and the given samples. ServerTimeUtc = source time + 1 s (so tests can tell them apart).</summary>
    public async Task<int> SeedAsync(string tag, params (DateTime T, HistorianValue V, uint Status)[] samples)
@@ -237,7 +238,8 @@ public sealed class RawReadTests(SqlHistorianFixture fx)
            ConnectionString = fx.ConnectionString, Schema = SqlHistorianFixture.UniqueSchema(), AutoCreateSchema = false,
        };
        var conn = new SqlHistorianConnection(o);
-        var boot = new SqlServerSchemaBootstrapper(conn, o);
+        var clock = new FixedClock(DateTimeOffset.UtcNow);
+        var boot = new SqlServerSchemaBootstrapper(conn, o, timeProvider: clock);
        var src = new SqlServerHistorianDataSource(conn, boot, new SqlServerTagCatalog(conn, boot));

        await Should.ThrowAsync<HistorianSchemaMissingException>(() => src.ReadRawAsync("A", At(0), At(1), 0, Ct));
@@ -251,6 +253,7 @@ public sealed class RawReadTests(SqlHistorianFixture fx)
        // Another node creates the schema; the same data source then succeeds (bootstrap failure is not latched).
        var creator = new SqlServerHistorianOptions { ConnectionString = o.ConnectionString, Schema = o.Schema };
        await new SqlServerSchemaBootstrapper(new SqlHistorianConnection(creator), creator).EnsureAsync(Ct);
+        clock.Now += SqlServerSchemaBootstrapper.FailureCacheDuration; // past the 5 s failure cache (M-2)
        (await src.ReadRawAsync("A", At(0), At(1), 0, Ct)).Samples.ShouldBeEmpty();
        src.GetHealthSnapshot().ConsecutiveFailures.ShouldBe(0);
    }
@@ -77,10 +77,37 @@ public sealed class SchemaBootstrapIntegrationTests(SqlHistorianFixture fx)
    {
        fx.SkipIfUnavailable();
        var s = SqlHistorianFixture.UniqueSchema();
-        var checker = Boot(Opts(s, auto: false));
+        var clock = new FixedClock(DateTimeOffset.UtcNow);
+        var o = Opts(s, auto: false);
+        var checker = new SqlServerSchemaBootstrapper(new SqlHistorianConnection(o), o, timeProvider: clock);
        await Should.ThrowAsync<HistorianSchemaMissingException>(() => checker.EnsureAsync(CancellationToken.None));
        await Boot(Opts(s)).EnsureAsync(CancellationToken.None);
-        await checker.EnsureAsync(CancellationToken.None); // same instance retries
+        clock.Now += SqlServerSchemaBootstrapper.FailureCacheDuration;
+        await checker.EnsureAsync(CancellationToken.None); // same instance retries once the failure cache expires
+    }
+
+    /// <summary>
+    ///     M-2: within <see cref="SqlServerSchemaBootstrapper.FailureCacheDuration"/> of a failure the bootstrapper
+    ///     re-throws it without touching SQL — proven by creating the schema in between: a call that went to SQL
+    ///     would now pass.
+    /// </summary>
+    [Fact]
+    public async Task A_bootstrap_failure_is_cached_for_five_seconds_then_retried()
+    {
+        fx.SkipIfUnavailable();
+        var s = SqlHistorianFixture.UniqueSchema();
+        var clock = new FixedClock(DateTimeOffset.UtcNow);
+        var o = Opts(s, auto: false);
+        var checker = new SqlServerSchemaBootstrapper(new SqlHistorianConnection(o), o, timeProvider: clock);
+        await Should.ThrowAsync<HistorianSchemaMissingException>(() => checker.EnsureAsync(CancellationToken.None));
+
+        await Boot(Opts(s)).EnsureAsync(CancellationToken.None); // the schema now exists
+
+        clock.Now += SqlServerSchemaBootstrapper.FailureCacheDuration - TimeSpan.FromTicks(1);
+        await Should.ThrowAsync<HistorianSchemaMissingException>(() => checker.EnsureAsync(CancellationToken.None));
+
+        clock.Now += TimeSpan.FromTicks(1);
+        await checker.EnsureAsync(CancellationToken.None);
    }

    [Fact]
@@ -89,7 +89,7 @@ public sealed class WriteTests(SqlHistorianFixture fx)
    }

    [Fact]
-    public async Task Non_finite_doubles_store_as_Empty_with_their_status_and_do_not_fail_the_write()
+    public async Task Non_finite_doubles_store_as_Empty_forced_Bad_and_do_not_fail_the_write()
    {
        fx.SkipIfUnavailable();
        var (w, s) = Make();
@@ -101,7 +101,8 @@ public sealed class WriteTests(SqlHistorianFixture fx)
        rows.Count.ShouldBe(3);
        rows[0].Kind.ShouldBe((byte)HistorianValueKind.Empty);
        rows[0].N.ShouldBeNull();
-        rows[0].Status.ShouldBe(unchecked((int)0x40000000u));
+        rows[0].Status.ShouldBe(unchecked((int)SqlHistorianStatusCodes.BadOutOfRange)); // Uncertain NaN ⇒ Bad (I-1)
+        rows[1].Status.ShouldBe(unchecked((int)SqlHistorianStatusCodes.BadOutOfRange)); // Good +Inf ⇒ Bad (I-1)
        rows[2].N.ShouldBe(7);
    }

@@ -32,6 +32,36 @@ public sealed class SqlServerHistorianProviderTests
        p.CreateUpdater(sp).ShouldBeOfType<SqlServerHistorianDataUpdater>();
    }

+    [Fact]
+    public void Supported_kinds_are_a_frozen_set() =>
+        Make().SupportedKinds.ShouldBeAssignableTo<System.Collections.Frozen.FrozenSet<HistorianValueKind>>();
+
+    /// <summary>
+    ///     An invalid schema must not fail provider construction (the host resolves the provider even when no
+    ///     consumer is enabled); it surfaces only when a seam is actually built.
+    /// </summary>
+    [Fact]
+    public void An_invalid_schema_fails_only_when_a_seam_is_built()
+    {
+        var p = new SqlServerHistorianProvider(new SqlServerHistorianOptions { ConnectionString = "x", Schema = "bad;schema" });
+        p.Name.ShouldBe("SqlServer");
+        Should.Throw<ArgumentException>(() => p.CreateDataSource(new NullSp()));
+    }
+
+    [Fact]
+    public void Every_seam_shares_one_connection_bootstrapper_and_catalog()
+    {
+        var sp = new NullSp();
+        var p = Make();
+        var a = (SqlServerHistorianDataSource)p.CreateDataSource(sp);
+        var b = (SqlServerHistorianDataSource)p.CreateDataSource(sp);
+        Field(a, "_bootstrap").ShouldBeSameAs(Field(b, "_bootstrap"));
+        Field(a, "_catalog").ShouldBeSameAs(Field(b, "_catalog"));
+    }
+
+    private static object? Field(object o, string name) =>
+        o.GetType().GetField(name, System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic)!.GetValue(o);
+
    private sealed class NullSp : IServiceProvider
    {
        public object? GetService(Type serviceType) => null;
@@ -22,6 +22,23 @@ public sealed class StatusCodeOracleTests
        ((uint)Opc.Ua.AggregateBits.Interpolated).ShouldBe(HistorianInfoBits.HistorianInterpolated);
    }

+    /// <summary>
+    ///     A stored status that already carries a historian bit (a sample written via HistoryUpdate with the Calculated
+    ///     bit, say) must come back with ONE historian bit, never both: the existing pair is masked off first. The SDK
+    ///     agrees — <c>SetAggregateBits</c> replaces, it does not OR.
+    /// </summary>
+    [Fact]
+    public void Setting_one_historian_bit_clears_the_other()
+    {
+        var calculatedUncertain = SqlHistorianStatusCodes.UncertainDataSubNormal | 0x400u | HistorianInfoBits.HistorianCalculated;
+        var interpolated = HistorianInfoBits.WithInterpolated(calculatedUncertain);
+        interpolated.ShouldBe(SqlHistorianStatusCodes.UncertainDataSubNormal | 0x400u | HistorianInfoBits.HistorianInterpolated);
+        new Opc.Ua.StatusCode(interpolated).AggregateBits.ShouldBe(Opc.Ua.AggregateBits.Interpolated);
+
+        var interpolatedGood = 0x400u | HistorianInfoBits.HistorianInterpolated;
+        HistorianInfoBits.WithCalculated(interpolatedGood).ShouldBe(0x400u | HistorianInfoBits.HistorianCalculated);
+    }
+
    [Fact]
    public void Info_type_is_data_value() =>
        HistorianInfoBits.InfoTypeDataValue.ShouldBe(0x400u);
@@ -9,18 +9,32 @@ public sealed class ValueWriterPrepareTests
    private static readonly DateTime T = new(2026, 10, 9, 1, 2, 3, DateTimeKind.Utc);

    [Fact]
-    public void Non_finite_doubles_become_Empty_keeping_status()
+    public void Non_finite_doubles_become_Empty_and_are_forced_Bad()
    {
-        const uint status = 0x40000000u;
+        const uint uncertain = 0x40000000u;
+        const uint badNoCommunication = 0x80310000u;
        var rows = SqlServerHistorianValueWriter.Prepare(
        [
-            new(T, HistorianValue.FromDouble(double.NaN), status),
+            new(T, HistorianValue.FromDouble(double.NaN), uncertain),
            new(T.AddTicks(1), HistorianValue.FromDouble(double.PositiveInfinity), 0),
-            new(T.AddTicks(2), HistorianValue.FromDouble(double.NegativeInfinity), 0),
+            new(T.AddTicks(2), HistorianValue.FromDouble(double.NegativeInfinity), badNoCommunication),
            new(T.AddTicks(3), HistorianValue.FromDouble(1.5), 0),
        ], () => T);
        rows.Select(r => r.Value.Kind).ShouldBe([HistorianValueKind.Empty, HistorianValueKind.Empty, HistorianValueKind.Empty, HistorianValueKind.Double]);
-        rows[0].StatusCode.ShouldBe(status);
+        rows.Select(r => r.StatusCode).ShouldBe([SqlHistorianStatusCodes.BadOutOfRange, SqlHistorianStatusCodes.BadOutOfRange,
+            badNoCommunication, 0u]);
+    }
+
+    [Fact]
+    public void A_non_bad_Empty_is_stored_BadNoData_and_a_bad_Empty_keeps_its_code()
+    {
+        var rows = SqlServerHistorianValueWriter.Prepare(
+        [
+            new(T, HistorianValue.Empty, 0),
+            new(T.AddTicks(1), HistorianValue.Empty, 0x40A40000u),
+            new(T.AddTicks(2), HistorianValue.Empty, 0x80310000u),
+        ], () => T);
+        rows.Select(r => r.StatusCode).ShouldBe([SqlHistorianStatusCodes.BadNoData, SqlHistorianStatusCodes.BadNoData, 0x80310000u]);
    }

    [Fact]