test(cli): add migration module registry coverage

src/Cli/__Tests/StellaOps.Cli.Tests/Commands/MigrationModuleRegistryTests.cs

@@ -0,0 +1,36 @@
+using System.Linq;
+using StellaOps.Cli.Services;
+using Xunit;
+
+namespace StellaOps.Cli.Tests.Commands;
+
+public class MigrationModuleRegistryTests
+{
+    [Fact]
+    public void Modules_Default_IsEmpty()
+    {
+        Assert.Empty(MigrationModuleRegistry.Modules);
+        Assert.Empty(MigrationModuleRegistry.ModuleNames);
+    }
+
+    [Fact]
+    public void FindModule_WhenEmpty_ReturnsNull()
+    {
+        var result = MigrationModuleRegistry.FindModule("Authority");
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void GetModules_Filtered_WhenEmpty_ReturnsEmpty()
+    {
+        var result = MigrationModuleRegistry.GetModules("Authority");
+        Assert.Empty(result);
+    }
+
+    [Fact]
+    public void GetModules_All_WhenEmpty_ReturnsEmpty()
+    {
+        var result = MigrationModuleRegistry.GetModules(null);
+        Assert.Empty(result);
+    }
+}