test(08-06): add PermissionLevelMapping and PermissionSummaryBuilder unit tests

- 9 tests for PermissionLevelMapping: known roles, unknown fallback, case insensitivity, splitting, risk ranking, labels
- 4 tests for PermissionSummaryBuilder: risk levels, empty input, distinct users, wrapping

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

SharepointToolbox.Tests/Models/PermissionSummaryBuilderTests.cs

@@ -0,0 +1,82 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Tests.Models;
+
+/// <summary>
+/// Unit tests for PermissionSummaryBuilder and SimplifiedPermissionEntry.
+/// SIMP-02: Validates summary aggregation, risk-level grouping, distinct user counting,
+/// and SimplifiedPermissionEntry wrapping behavior.
+/// </summary>
+public class PermissionSummaryBuilderTests
+{
+    private static PermissionEntry MakeEntry(string permLevels, string users = "User1", string logins = "user1@test.com") =>
+        new PermissionEntry(
+            ObjectType: "Site",
+            Title: "Test",
+            Url: "https://test.sharepoint.com",
+            HasUniquePermissions: true,
+            Users: users,
+            UserLogins: logins,
+            PermissionLevels: permLevels,
+            GrantedThrough: "Direct Permissions",
+            PrincipalType: "User");
+
+    [Fact]
+    public void Build_ReturnsAllFourRiskLevels()
+    {
+        var entries = SimplifiedPermissionEntry.WrapAll(new[]
+        {
+            MakeEntry("Full Control"),
+            MakeEntry("Contribute"),
+            MakeEntry("Read"),
+            MakeEntry("View Only")
+        });
+
+        var summaries = PermissionSummaryBuilder.Build(entries);
+
+        Assert.Equal(4, summaries.Count);
+        Assert.Contains(summaries, s => s.RiskLevel == RiskLevel.High && s.Count == 1);
+        Assert.Contains(summaries, s => s.RiskLevel == RiskLevel.Medium && s.Count == 1);
+        Assert.Contains(summaries, s => s.RiskLevel == RiskLevel.Low && s.Count == 1);
+        Assert.Contains(summaries, s => s.RiskLevel == RiskLevel.ReadOnly && s.Count == 1);
+    }
+
+    [Fact]
+    public void Build_EmptyCollection_ReturnsZeroCounts()
+    {
+        var summaries = PermissionSummaryBuilder.Build(Array.Empty<SimplifiedPermissionEntry>());
+
+        Assert.Equal(4, summaries.Count);
+        Assert.All(summaries, s => Assert.Equal(0, s.Count));
+    }
+
+    [Fact]
+    public void Build_CountsDistinctUsers()
+    {
+        var entries = SimplifiedPermissionEntry.WrapAll(new[]
+        {
+            MakeEntry("Full Control", "Alice", "alice@test.com"),
+            MakeEntry("Full Control", "Bob", "bob@test.com"),
+            MakeEntry("Full Control", "Alice", "alice@test.com"),  // duplicate user
+        });
+
+        var summaries = PermissionSummaryBuilder.Build(entries);
+        var high = summaries.Single(s => s.RiskLevel == RiskLevel.High);
+
+        Assert.Equal(3, high.Count);          // 3 entries
+        Assert.Equal(2, high.DistinctUsers);   // 2 distinct users
+    }
+
+    [Fact]
+    public void SimplifiedPermissionEntry_WrapAll_PreservesInner()
+    {
+        var original = MakeEntry("Contribute");
+        var wrapped = SimplifiedPermissionEntry.WrapAll(new[] { original });
+
+        Assert.Single(wrapped);
+        Assert.Same(original, wrapped[0].Inner);
+        Assert.Equal("Contribute", wrapped[0].PermissionLevels);
+        Assert.Equal(RiskLevel.Medium, wrapped[0].RiskLevel);
+        Assert.Contains("Can edit", wrapped[0].SimplifiedLabels);
+    }
+}