fix(review): calc ReadOne reports an inputs-Bad publish; VT inputs-bad counter ticks only on a real report

2026-08-20 11:48:41 -04:00
parent 74794f4365
commit 886082fec7
6 changed files with 152 additions and 6 deletions
@@ -270,6 +270,38 @@ public sealed class CalculationDriverInputQualityTests
        read[0].Value.ShouldBe(bad.Snapshot.Value);
    }

+    /// <summary>
+    ///     A tag whose ONLY publish was inputs-Bad — it never produced a value — must read back that Bad
+    ///     status, not <c>BadWaitingForInitialData</c>. Guarding the read on "has a value" rather than
+    ///     "has published" made a polled read say "never polled" while the subscriber on the same node had
+    ///     been told <c>BadNoCommunication</c>: the two clients disagree, and the read is the one that
+    ///     lies (something HAS been observed about this tag — that its input is dead).
+    /// </summary>
+    [Fact]
+    public async Task ReadAsync_after_an_inputs_Bad_with_no_prior_value_reports_the_bad_status()
+    {
+        var (driver, published, _) = Build(CalcTag(SumTag, SumScript));
+        await driver.InitializeAsync("{}", TestContext.Current.CancellationToken);
+
+        // The first thing that ever happens to this tag is a dead input — no successful evaluation, so
+        // there is no last value to carry.
+        driver.OnDependencyValue("src/a", null, StatusBadNoCommunication, DateTime.UtcNow);
+        driver.OnDependencyValue("src/b", 20.0, StatusGood, DateTime.UtcNow);
+        await Settle(driver);
+
+        published.Count.ShouldBe(1);
+        published.TryDequeue(out var bad).ShouldBeTrue();
+        bad!.Snapshot.StatusCode.ShouldBe(StatusBadNoCommunication);
+        bad.Snapshot.Value.ShouldBeNull();
+
+        var read = await driver.ReadAsync([SumTag], TestContext.Current.CancellationToken);
+
+        read[0].StatusCode.ShouldBe(StatusBadNoCommunication);
+        read[0].StatusCode.ShouldNotBe(StatusBadWaitingForInitialData,
+            "something HAS been observed about this tag — that its input is dead");
+        read[0].Value.ShouldBeNull();
+    }
+
    /// <summary>A never-evaluated tag still reads BadWaitingForInitialData (regression).</summary>
    [Fact]
    public async Task An_unevaluated_tag_still_reads_BadWaitingForInitialData()