fix(driver-abcip-cli): resolve Low code-review findings (Driver.AbCip.Cli-003,004,005,006,007,008)

- Driver.AbCip.Cli-003: SubscribeCommand prints the 'Subscribed' banner BEFORE wiring OnDataChange so the main thread can't interleave its write with the poll-thread handler. - Driver.AbCip.Cli-004: AbCipCommandBase.Timeout and SubscribeCommand validate TimeoutMs / IntervalMs and throw CommandException on non-positive values. - Driver.AbCip.Cli-005: every command now calls FlushLogging() in its finally block. - Driver.AbCip.Cli-006: Timeout init throws NotSupportedException with a pointer at TimeoutMs instead of silently swallowing assignments. - Driver.AbCip.Cli-007: added AbCipCommandBaseTests covering BuildOptions shape, probe / controller-browse / alarm toggles, host address, family selection, tag list passthrough. - Driver.AbCip.Cli-008: rewrote the opening paragraph in docs/Driver.AbCip.Cli.md to credit the six-CLI roster with a pointer at docs/DriverClis.md. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-23 08:34:25 -04:00
parent 61c0311938
commit 759af8c1bb
9 changed files with 348 additions and 20 deletions
--- a/code-reviews/Driver.AbCip.Cli/findings.md
+++ b/code-reviews/Driver.AbCip.Cli/findings.md
@@ -7,7 +7,7 @@
 | Review date | 2026-05-22 |
 | Commit reviewed | `76d35d1` |
 | Status | Reviewed |
-| Open findings | 6 |
+| Open findings | 0 |

 ## Checklist coverage

@@ -96,7 +96,7 @@ into `AbCipCommandBase`.
 | Severity | Low |
 | Category | Concurrency & thread safety |
 | Location | `src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/SubscribeCommand.cs:50-56,60-61` |
-| Status | Open |
+| Status | Resolved |

 **Description:** The `OnDataChange` handler writes change lines to `console.Output`
 (a `TextWriter`) from the driver's poll-engine callback thread, while the command's
@@ -112,7 +112,12 @@ during the watch loop widens it.
 writes during the subscription with a shared lock so poll-thread and main-thread
 output cannot interleave.

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — moved the "Subscribed to ... Ctrl+C to stop."
+banner write to BEFORE `driver.OnDataChange +=` (and therefore before
+`SubscribeAsync`). With the handler not yet attached when the banner runs, the
+poll thread cannot fire change events into `console.Output` concurrently with the
+main-thread banner write. After `+=` the only writer to `console.Output` is the
+poll-thread handler, so no interleaving is possible.

 ### Driver.AbCip.Cli-004

@@ -121,7 +126,7 @@ output cannot interleave.
 | Severity | Low |
 | Category | Error handling & resilience |
 | Location | `src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/SubscribeCommand.cs:28,58`; `AbCipCommandBase.cs:26-34` |
-| Status | Open |
+| Status | Resolved |

 **Description:** `--interval-ms` (`IntervalMs`) is taken verbatim and passed as
 `TimeSpan.FromMilliseconds(IntervalMs)` to `SubscribeAsync` with no validation. A
@@ -135,7 +140,16 @@ downstream component to sanitise operator input is fragile. `--timeout-ms` on
 `ExecuteAsync` / in `AbCipCommandBase`, throwing a `CommandException` with the
 accepted range when out of bounds.

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — added `SubscribeCommand.ValidateInterval(int)`
+(throws `CommandException` for `IntervalMs <= 0`) called at the top of
+`SubscribeCommand.ExecuteAsync`; moved `TimeoutMs > 0` validation into the
+`AbCipCommandBase.Timeout` getter (throws `CommandException` for non-positive
+`TimeoutMs`) and added a `_ = Timeout` touch in `SubscribeCommand.ExecuteAsync` to
+fire that guard before the driver opens. Other commands trip the same guard
+naturally via `BuildOptions(...).Timeout`. Regression tests
+`AbCipCommandBaseTests.Timeout_get_throws_CommandException_when_TimeoutMs_is_non_positive`
+and `SubscribeCommandIntervalTests.ValidateInterval_rejects_non_positive` cover
+both paths.

 ### Driver.AbCip.Cli-005

@@ -144,7 +158,7 @@ accepted range when out of bounds.
 | Severity | Low |
 | Category | Performance & resource management |
 | Location | `src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.Cli.Common/DriverCommandBase.cs:51-59` |
-| Status | Open |
+| Status | Resolved |

 **Description:** `ConfigureLogging` assigns a freshly created Serilog logger to the
 process-global `Log.Logger` but never calls `Log.CloseAndFlush()`. For a short-lived
@@ -159,7 +173,12 @@ module's review.)
 `AppDomain.ProcessExit` or a `finally` in the command), or have the CLI use a
 disposable logger scoped to `ExecuteAsync`.

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — `Driver.Cli.Common` already exposes
+`DriverCommandBase.FlushLogging()` (a `Log.CloseAndFlush()` wrapper); the AB CIP
+CLI was not calling it. Added `FlushLogging()` in the `finally` block of all four
+commands (`ProbeCommand`, `ReadCommand`, `WriteCommand`, `SubscribeCommand`) so
+buffered Serilog output is flushed before the process exits, including the
+Ctrl+C-driven `subscribe` path. No edits to `Driver.Cli.Common` were needed.

 ### Driver.AbCip.Cli-006

@@ -168,7 +187,7 @@ disposable logger scoped to `ExecuteAsync`.
 | Severity | Low |
 | Category | Design-document adherence |
 | Location | `src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/AbCipCommandBase.cs:29-34` |
-| Status | Open |
+| Status | Resolved |

 **Description:** `AbCipCommandBase` overrides the abstract `DriverCommandBase.Timeout`
 property with a getter derived from `TimeoutMs` and an empty `init` body
@@ -183,9 +202,13 @@ bug.
 **Recommendation:** Either drop the `init` accessor entirely (make the override a
 get-only expression-bodied property) or have the empty `init` throw
 `NotSupportedException` to make the "driven by TimeoutMs" contract explicit and
-fail-fast.
+fail-fast. (Drop is not viable because the abstract base declares `{ get; init; }`
+and an override must provide both accessors.)

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — the `init` accessor now throws
+`NotSupportedException` with a message pointing the caller at `TimeoutMs`. A new
+test `AbCipCommandBaseTests.Timeout_setter_is_inert_and_does_not_silently_swallow_assignments`
+asserts that an object-initializer assignment to `Timeout` fails fast.

 ### Driver.AbCip.Cli-007

@@ -194,7 +217,7 @@ fail-fast.
 | Severity | Low |
 | Category | Testing coverage |
 | Location | `tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests/WriteCommandParseValueTests.cs` |
-| Status | Open |
+| Status | Resolved |

 **Description:** The only test file covers `WriteCommand.ParseValue` and
 `ReadCommand.SynthesiseTagName` — both pure static helpers. There is no coverage for
@@ -213,7 +236,12 @@ driver CLIs.
 (`HostAddress`, `PlcFamily`, `DeviceName`), the supplied tag list, and the `Timeout`
 derived from `TimeoutMs`.

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — added
+`tests/.../AbCipCommandBaseTests.cs` covering `BuildOptions` (probe disabled,
+controller-browse disabled, alarm-projection disabled, single device with
+`HostAddress` / `PlcFamily` / `cli-{Family}` device name, tag list passed verbatim,
+`Timeout` derived from `TimeoutMs`) and `DriverInstanceId` (`abcip-cli-{Gateway}`),
+plus the `RejectStructure` guard (throws for `Structure`, no-op for atomic types).

 ### Driver.AbCip.Cli-008

@@ -222,7 +250,7 @@ derived from `TimeoutMs`.
 | Severity | Low |
 | Category | Documentation & comments |
 | Location | `docs/Driver.AbCip.Cli.md:8-9` |
-| Status | Open |
+| Status | Resolved |

 **Description:** `docs/Driver.AbCip.Cli.md` opens with "Second of four driver
 test-client CLIs (Modbus -> AB CIP -> AB Legacy -> S7 -> TwinCAT)." The count "four"
@@ -235,4 +263,6 @@ doc's "four" and the truncated chain are both stale.
 and complete the chain (Modbus -> AB CIP -> AB Legacy -> S7 -> TwinCAT -> FOCAS), or
 drop the explicit count and link `docs/DriverClis.md` as the authoritative roster.

-**Resolution:** _(open)_
+**Resolution:** Resolved 2026-05-23 — rewrote the lead paragraph to "Second of six
+driver test-client CLIs (Modbus -> AB CIP -> AB Legacy -> S7 -> TwinCAT -> FOCAS)"
+and added a link to `docs/DriverClis.md` as the authoritative roster.
--- a/docs/Driver.AbCip.Cli.md
+++ b/docs/Driver.AbCip.Cli.md
@@ -4,8 +4,9 @@ Ad-hoc probe / read / write / subscribe tool for ControlLogix / CompactLogix /
 Micro800 / GuardLogix PLCs, talking to the **same** `AbCipDriver` the OtOpcUa
 server uses (libplctag under the hood).

-Second of four driver test-client CLIs (Modbus → AB CIP → AB Legacy → S7 →
-TwinCAT). Shares `Driver.Cli.Common` with the others.
+Second of six driver test-client CLIs (Modbus → AB CIP → AB Legacy → S7 →
+TwinCAT → FOCAS). Shares `Driver.Cli.Common` with the others; see
+[DriverClis.md](DriverClis.md) for the authoritative roster.

 ## Build + run

--- a/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/AbCipCommandBase.cs
+++ b/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/AbCipCommandBase.cs
@@ -27,10 +27,28 @@ public abstract class AbCipCommandBase : DriverCommandBase
    public int TimeoutMs { get; init; } = 5000;

    /// <inheritdoc />
+    /// <remarks>
+    ///     The getter validates <see cref="TimeoutMs"/> (Driver.AbCip.Cli-004) — a zero or
+    ///     negative <c>--timeout-ms</c> would otherwise propagate as a non-positive
+    ///     <see cref="TimeSpan"/> into the driver. The <c>init</c> accessor is unreachable
+    ///     because CliFx binds <see cref="TimeoutMs"/> rather than <c>Timeout</c>; it throws
+    ///     <see cref="NotSupportedException"/> so an object-initializer assignment
+    ///     (<c>new ReadCommand { Timeout = ... }</c>) fails fast instead of being silently
+    ///     discarded (Driver.AbCip.Cli-006).
+    /// </remarks>
    public override TimeSpan Timeout
    {
-        get => TimeSpan.FromMilliseconds(TimeoutMs);
-        init { /* driven by TimeoutMs */ }
+        get
+        {
+            if (TimeoutMs <= 0)
+                throw new CliFx.Exceptions.CommandException(
+                    $"--timeout-ms must be > 0 (got {TimeoutMs}). " +
+                    "Pick a positive number of milliseconds for the per-operation timeout.");
+            return TimeSpan.FromMilliseconds(TimeoutMs);
+        }
+        init => throw new NotSupportedException(
+            $"{nameof(AbCipCommandBase)}.{nameof(Timeout)} is derived from {nameof(TimeoutMs)} " +
+            "and cannot be assigned directly. Set TimeoutMs instead.");
    }

    /// <summary>
--- a/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/ProbeCommand.cs
+++ b/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/ProbeCommand.cs
@@ -54,6 +54,9 @@ public sealed class ProbeCommand : AbCipCommandBase
        finally
        {
            await driver.ShutdownAsync(CancellationToken.None);
+            // Driver.AbCip.Cli-005 — flush Serilog before process exit so buffered log
+            // output emitted during driver shutdown is not lost.
+            FlushLogging();
        }
    }
 }
--- a/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/ReadCommand.cs
+++ b/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/ReadCommand.cs
@@ -49,6 +49,9 @@ public sealed class ReadCommand : AbCipCommandBase
        finally
        {
            await driver.ShutdownAsync(CancellationToken.None);
+            // Driver.AbCip.Cli-005 — flush Serilog before process exit so buffered log
+            // output emitted during driver shutdown is not lost.
+            FlushLogging();
        }
    }

--- a/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/SubscribeCommand.cs
+++ b/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/SubscribeCommand.cs
@@ -31,6 +31,10 @@ public sealed class SubscribeCommand : AbCipCommandBase
    {
        ConfigureLogging();
        RejectStructure(DataType);
+        ValidateInterval(IntervalMs);
+        // Touch Timeout to surface the --timeout-ms guard (Driver.AbCip.Cli-004) before
+        // we open a driver — fast-fail with a clean CommandException on bad operator input.
+        _ = Timeout;
        var ct = console.RegisterCancellationHandler();

        var tagName = ReadCommand.SynthesiseTagName(TagPath, DataType);
@@ -48,6 +52,13 @@ public sealed class SubscribeCommand : AbCipCommandBase
        {
            await driver.InitializeAsync("{}", ct);

+            // Driver.AbCip.Cli-003 — emit the banner BEFORE wiring OnDataChange so the
+            // main-thread write cannot interleave with poll-thread change-event writes.
+            // TextWriter.WriteLine is not guaranteed thread-safe; once the handler is
+            // attached and SubscribeAsync starts, change events run on the poll thread.
+            await console.Output.WriteLineAsync(
+                $"Subscribed to {TagPath} @ {IntervalMs}ms. Ctrl+C to stop.");
+
            driver.OnDataChange += (_, e) =>
            {
                var line = $"[{DateTime.UtcNow:HH:mm:ss.fff}] " +
@@ -58,8 +69,6 @@ public sealed class SubscribeCommand : AbCipCommandBase

            handle = await driver.SubscribeAsync([tagName], TimeSpan.FromMilliseconds(IntervalMs), ct);

-            await console.Output.WriteLineAsync(
-                $"Subscribed to {TagPath} @ {IntervalMs}ms. Ctrl+C to stop.");
            try
            {
                await Task.Delay(System.Threading.Timeout.InfiniteTimeSpan, ct);
@@ -77,6 +86,23 @@ public sealed class SubscribeCommand : AbCipCommandBase
                catch { /* teardown best-effort */ }
            }
            await driver.ShutdownAsync(CancellationToken.None);
+            // Driver.AbCip.Cli-005 — flush Serilog before process exit so buffered log
+            // lines emitted just before Ctrl+C are not lost on abrupt termination.
+            FlushLogging();
        }
    }
+
+    /// <summary>
+    ///     Guards <c>--interval-ms</c> against zero or negative values (Driver.AbCip.Cli-004).
+    ///     A non-positive interval would produce a non-positive <see cref="TimeSpan"/> into
+    ///     <c>SubscribeAsync</c>; the CLI should fail fast with an actionable error rather
+    ///     than relying on the downstream <c>PollGroupEngine</c> to clamp the value.
+    /// </summary>
+    internal static void ValidateInterval(int intervalMs)
+    {
+        if (intervalMs <= 0)
+            throw new CliFx.Exceptions.CommandException(
+                $"--interval-ms must be > 0 (got {intervalMs}). " +
+                "PollGroupEngine floors sub-250ms values, but accepts any positive integer.");
+    }
 }
--- a/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/WriteCommand.cs
+++ b/src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/WriteCommand.cs
@@ -60,6 +60,9 @@ public sealed class WriteCommand : AbCipCommandBase
        finally
        {
            await driver.ShutdownAsync(CancellationToken.None);
+            // Driver.AbCip.Cli-005 — flush Serilog before process exit so buffered log
+            // output emitted during driver shutdown is not lost.
+            FlushLogging();
        }
    }

--- a/tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests/AbCipCommandBaseTests.cs
+++ b/tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests/AbCipCommandBaseTests.cs
@@ -0,0 +1,210 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Commands;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests;
+
+/// <summary>
+///     Covers <see cref="AbCipCommandBase"/>: the shared <c>BuildOptions</c> projection
+///     (driver-options mapping the four commands depend on), the <c>RejectStructure</c>
+///     guard, the <c>Timeout</c> override behaviour, and <c>TimeoutMs</c> validation.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class AbCipCommandBaseTests
+{
+    /// <summary>
+    ///     Local subclass that surfaces the protected helpers + properties under test.
+    /// </summary>
+    [CliFx.Attributes.Command("test")]
+    private sealed class TestableCommand : AbCipCommandBase
+    {
+        public AbCipDriverOptions InvokeBuildOptions(IReadOnlyList<AbCipTagDefinition> tags)
+            => BuildOptions(tags);
+
+        public string InvokeDriverInstanceId => DriverInstanceId;
+
+        public override ValueTask ExecuteAsync(CliFx.Infrastructure.IConsole console)
+            => ValueTask.CompletedTask;
+    }
+
+    private static AbCipTagDefinition SampleTag(string name = "Motor01") => new(
+        Name: name,
+        DeviceHostAddress: "ab://10.0.0.5/1,0",
+        TagPath: "Motor01",
+        DataType: AbCipDataType.DInt,
+        Writable: false);
+
+    [Fact]
+    public void BuildOptions_disables_probe_so_cli_does_not_race_operator_reads()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+            TimeoutMs = 5000,
+        };
+
+        var options = cmd.InvokeBuildOptions([SampleTag()]);
+
+        options.Probe.Enabled.ShouldBeFalse();
+    }
+
+    [Fact]
+    public void BuildOptions_disables_controller_browse()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+            TimeoutMs = 5000,
+        };
+
+        var options = cmd.InvokeBuildOptions([SampleTag()]);
+
+        options.EnableControllerBrowse.ShouldBeFalse();
+    }
+
+    [Fact]
+    public void BuildOptions_disables_alarm_projection()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+            TimeoutMs = 5000,
+        };
+
+        var options = cmd.InvokeBuildOptions([SampleTag()]);
+
+        options.EnableAlarmProjection.ShouldBeFalse();
+    }
+
+    [Fact]
+    public void BuildOptions_produces_one_device_with_gateway_family_and_derived_name()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.CompactLogix,
+            TimeoutMs = 5000,
+        };
+
+        var options = cmd.InvokeBuildOptions([SampleTag()]);
+
+        options.Devices.Count.ShouldBe(1);
+        var device = options.Devices[0];
+        device.HostAddress.ShouldBe("ab://10.0.0.5/1,0");
+        device.PlcFamily.ShouldBe(AbCipPlcFamily.CompactLogix);
+        device.DeviceName.ShouldBe("cli-CompactLogix");
+    }
+
+    [Fact]
+    public void BuildOptions_passes_supplied_tag_list_verbatim()
+    {
+        var tags = new[] { SampleTag("t1"), SampleTag("t2") };
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+            TimeoutMs = 5000,
+        };
+
+        var options = cmd.InvokeBuildOptions(tags);
+
+        options.Tags.Count.ShouldBe(2);
+        options.Tags[0].Name.ShouldBe("t1");
+        options.Tags[1].Name.ShouldBe("t2");
+    }
+
+    [Fact]
+    public void BuildOptions_carries_TimeoutMs_through_to_Timeout()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+            TimeoutMs = 7500,
+        };
+
+        var options = cmd.InvokeBuildOptions([SampleTag()]);
+
+        options.Timeout.ShouldBe(TimeSpan.FromMilliseconds(7500));
+    }
+
+    [Fact]
+    public void DriverInstanceId_embeds_gateway_for_log_disambiguation()
+    {
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Family = AbCipPlcFamily.ControlLogix,
+        };
+
+        cmd.InvokeDriverInstanceId.ShouldBe("abcip-cli-ab://10.0.0.5/1,0");
+    }
+
+    [Fact]
+    public void Timeout_setter_is_inert_and_does_not_silently_swallow_assignments()
+    {
+        // Driver.AbCip.Cli-006 — the empty init body would silently discard an
+        // object-initializer assignment, hiding a "driven by TimeoutMs" misuse. The fix
+        // makes it fail-fast with NotSupportedException so the contract is explicit.
+        Should.Throw<NotSupportedException>(() => new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            Timeout = TimeSpan.FromSeconds(99),
+        });
+    }
+
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    public void Timeout_get_throws_CommandException_when_TimeoutMs_is_non_positive(int badMs)
+    {
+        // Driver.AbCip.Cli-004 — TimeoutMs must be > 0. Validation is exposed via the
+        // Timeout getter so any command path that touches Timeout sees the same guard.
+        var cmd = new TestableCommand
+        {
+            Gateway = "ab://10.0.0.5/1,0",
+            TimeoutMs = badMs,
+        };
+
+        var ex = Should.Throw<CliFx.Exceptions.CommandException>(() => _ = cmd.Timeout);
+        ex.Message.ShouldContain("--timeout-ms");
+    }
+
+    [Fact]
+    public void RejectStructure_throws_for_Structure_DataType()
+    {
+        var ex = Should.Throw<CliFx.Exceptions.CommandException>(
+            () => CallRejectStructure(AbCipDataType.Structure));
+        ex.Message.ShouldContain("Structure");
+    }
+
+    [Theory]
+    [InlineData(AbCipDataType.DInt)]
+    [InlineData(AbCipDataType.Bool)]
+    [InlineData(AbCipDataType.Real)]
+    public void RejectStructure_passes_for_atomic_types(AbCipDataType type)
+    {
+        // No throw — atomic types are allowed.
+        Should.NotThrow(() => CallRejectStructure(type));
+    }
+
+    // The static helper is protected; reflect to it once so the test stays at AbCipCommandBase.
+    private static void CallRejectStructure(AbCipDataType type)
+    {
+        var method = typeof(AbCipCommandBase).GetMethod(
+            "RejectStructure",
+            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static)
+            ?? throw new InvalidOperationException("RejectStructure not found");
+        try
+        {
+            method.Invoke(null, [type]);
+        }
+        catch (System.Reflection.TargetInvocationException tie) when (tie.InnerException is not null)
+        {
+            throw tie.InnerException;
+        }
+    }
+}
--- a/tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests/SubscribeCommandIntervalTests.cs
+++ b/tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests/SubscribeCommandIntervalTests.cs
@@ -0,0 +1,34 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Commands;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli.Tests;
+
+/// <summary>
+///     Covers <see cref="SubscribeCommand.ValidateInterval(int)"/> — the guard that
+///     stops a zero / negative <c>--interval-ms</c> from reaching <c>SubscribeAsync</c>
+///     as a non-positive <see cref="TimeSpan"/>.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class SubscribeCommandIntervalTests
+{
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    [InlineData(-500)]
+    public void ValidateInterval_rejects_non_positive(int badMs)
+    {
+        var ex = Should.Throw<CliFx.Exceptions.CommandException>(
+            () => SubscribeCommand.ValidateInterval(badMs));
+        ex.Message.ShouldContain("--interval-ms");
+    }
+
+    [Theory]
+    [InlineData(1)]
+    [InlineData(250)]
+    [InlineData(60_000)]
+    public void ValidateInterval_accepts_positive(int goodMs)
+    {
+        Should.NotThrow(() => SubscribeCommand.ValidateInterval(goodMs));
+    }
+}