feat(cli): scadalink audit verify-chain subcommand v1 no-op (#23 M8)

tests/ScadaLink.CLI.Tests/Commands/AuditCommandTestHarness.cs

@@ -25,15 +25,38 @@ internal static class AuditCommandTestHarness
         return root;
     }
 
+    /// <summary>
+    /// Parses and invokes the command tree, capturing output from both channels the CLI
+    /// uses: System.CommandLine's parser diagnostics flow through the
+    /// <see cref="InvocationConfiguration"/> writers, while command actions write through
+    /// <see cref="Console"/> (consistent with the rest of the CLI). Both are merged into
+    /// the returned <c>Out</c>/<c>Err</c> strings. Callers must be in the <c>Console</c>
+    /// xUnit collection so the global <see cref="Console"/> redirect is not racy.
+    /// </summary>
     public static (int Exit, string Out, string Err) Invoke(RootCommand root, params string[] args)
     {
         var output = new StringWriter();
         var error = new StringWriter();
-        var exit = root.Parse(args).Invoke(new InvocationConfiguration
+
+        var originalOut = Console.Out;
+        var originalErr = Console.Error;
+        Console.SetOut(output);
+        Console.SetError(error);
+        int exit;
+        try
+        {
+            exit = root.Parse(args).Invoke(new InvocationConfiguration
             {
                 Output = output,
                 Error = error,
             });
+        }
+        finally
+        {
+            Console.SetOut(originalOut);
+            Console.SetError(originalErr);
+        }
+
         return (exit, output.ToString(), error.ToString());
     }
 }

tests/ScadaLink.CLI.Tests/Commands/AuditExportCommandTests.cs

@@ -11,6 +11,7 @@ namespace ScadaLink.CLI.Tests.Commands;
 /// required-flag enforcement, query-string construction, streaming the response body
 /// to the output file, and the parquet-not-implemented (501) path.
 /// </summary>
+[Collection("Console")]
 public class AuditExportCommandTests
 {
     // ---- CLI parsing: required flags --------------------------------------

tests/ScadaLink.CLI.Tests/Commands/AuditQueryCommandTests.cs

@@ -12,6 +12,7 @@ namespace ScadaLink.CLI.Tests.Commands;
 /// time-spec resolution, query-string construction, formatter selection, error
 /// handling, and keyset-cursor paging via <c>--all</c>.
 /// </summary>
+[Collection("Console")]
 public class AuditQueryCommandTests
 {
     // ---- Time-spec parsing -------------------------------------------------

tests/ScadaLink.CLI.Tests/Commands/AuditVerifyChainCommandTests.cs

@@ -0,0 +1,58 @@
+using ScadaLink.CLI.Commands;
+
+namespace ScadaLink.CLI.Tests.Commands;
+
+/// <summary>
+/// Tests for the <c>scadalink audit verify-chain</c> subcommand (Audit Log #23 M8-T4).
+/// v1 is a no-op stub: a valid <c>--month</c> prints the documented "not enabled"
+/// message and exits 0; a malformed month or a missing <c>--month</c> exits non-zero.
+/// </summary>
+[Collection("Console")]
+public class AuditVerifyChainCommandTests
+{
+    [Fact]
+    public void VerifyChain_ValidMonth_ExitsZeroWithDocumentedMessage()
+    {
+        var root = AuditCommandTestHarness.BuildRoot();
+        var (exit, output, _) = AuditCommandTestHarness.Invoke(
+            root, "audit", "verify-chain", "--month", "2026-05");
+
+        Assert.Equal(0, exit);
+        Assert.Contains("Hash-chain tamper-evidence is not enabled", output);
+        Assert.Contains("Component-AuditLog.md", output);
+    }
+
+    [Fact]
+    public void VerifyChain_MalformedMonth_ExitsNonZero()
+    {
+        var root = AuditCommandTestHarness.BuildRoot();
+        var (exit, _, _) = AuditCommandTestHarness.Invoke(
+            root, "audit", "verify-chain", "--month", "2026-13");
+
+        Assert.NotEqual(0, exit);
+    }
+
+    [Fact]
+    public void VerifyChain_MissingMonth_ProducesRequiredFlagError()
+    {
+        var root = AuditCommandTestHarness.BuildRoot();
+        var (exit, _, err) = AuditCommandTestHarness.Invoke(root, "audit", "verify-chain");
+
+        Assert.NotEqual(0, exit);
+        Assert.Contains("--month", err);
+    }
+
+    [Theory]
+    [InlineData("2026-05", true)]
+    [InlineData("2026-01", true)]
+    [InlineData("2026-12", true)]
+    [InlineData("2026-13", false)]
+    [InlineData("2026-00", false)]
+    [InlineData("2026-5", false)]
+    [InlineData("not-a-month", false)]
+    [InlineData("", false)]
+    public void IsValidMonth_ValidatesYyyyMm(string month, bool expected)
+    {
+        Assert.Equal(expected, AuditVerifyChainHelpers.IsValidMonth(month));
+    }
+}