Refactor code structure for improved readability and maintainability; optimize performance in key functions.

src/Scanner/__Tests/StellaOps.Scanner.SmartDiff.Tests/DeltaVerdictBuilderTests.cs

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// Copyright (c) StellaOps Contributors
+
+using System.Collections.Immutable;
+using StellaOps.Attestor.ProofChain.Predicates;
+using StellaOps.Scanner.SmartDiff.Attestation;
+using StellaOps.Scanner.SmartDiff.Detection;
+using Xunit;
+
+namespace StellaOps.Scanner.SmartDiffTests;
+
+public sealed class DeltaVerdictBuilderTests
+{
+    [Fact]
+    public void BuildStatement_BuildsPredicateAndSubjects()
+    {
+        var changes = new[]
+        {
+            new MaterialRiskChangeResult(
+                FindingKey: new FindingKey("CVE-2025-0001", "pkg:npm/a@1.0.0"),
+                HasMaterialChange: true,
+                Changes: ImmutableArray.Create(new DetectedChange(
+                    Rule: DetectionRule.R1_ReachabilityFlip,
+                    ChangeType: MaterialChangeType.ReachabilityFlip,
+                    Direction: RiskDirection.Increased,
+                    Reason: "reachability_flip",
+                    PreviousValue: "false",
+                    CurrentValue: "true",
+                    Weight: 1.0)),
+                PriorityScore: 100,
+                PreviousStateHash: "sha256:prev",
+                CurrentStateHash: "sha256:curr"),
+            new MaterialRiskChangeResult(
+                FindingKey: new FindingKey("CVE-2025-0002", "pkg:npm/b@2.0.0"),
+                HasMaterialChange: true,
+                Changes: ImmutableArray.Create(new DetectedChange(
+                    Rule: DetectionRule.R2_VexFlip,
+                    ChangeType: MaterialChangeType.VexFlip,
+                    Direction: RiskDirection.Decreased,
+                    Reason: "vex_flip",
+                    PreviousValue: "affected",
+                    CurrentValue: "not_affected",
+                    Weight: 0.7)),
+                PriorityScore: 50,
+                PreviousStateHash: "sha256:prev2",
+                CurrentStateHash: "sha256:curr2")
+        };
+
+        var request = new DeltaVerdictBuildRequest
+        {
+            BeforeRevisionId = "rev-before",
+            AfterRevisionId = "rev-after",
+            BeforeImageDigest = "sha256:before",
+            AfterImageDigest = "sha256:after",
+            Changes = changes,
+            ComparedAt = new DateTimeOffset(2025, 12, 22, 0, 0, 0, TimeSpan.Zero),
+            BeforeProofSpine = new AttestationReference { Digest = "sha256:spine-before" },
+            AfterProofSpine = new AttestationReference { Digest = "sha256:spine-after" }
+        };
+
+        var builder = new DeltaVerdictBuilder();
+        var statement = builder.BuildStatement(request);
+
+        Assert.Equal(2, statement.Subject.Count);
+        Assert.Equal("delta-verdict.stella/v1", statement.PredicateType);
+        Assert.True(statement.Predicate.HasMaterialChange);
+        Assert.Equal(150, statement.Predicate.PriorityScore);
+        Assert.Equal("rev-before", statement.Predicate.BeforeRevisionId);
+        Assert.Equal("rev-after", statement.Predicate.AfterRevisionId);
+        Assert.Equal(2, statement.Predicate.Changes.Length);
+        Assert.Equal("R1", statement.Predicate.Changes[0].Rule);
+        Assert.Equal("increased", statement.Predicate.Changes[0].Direction);
+    }
+}

src/Scanner/__Tests/StellaOps.Scanner.SmartDiff.Tests/SarifOutputGeneratorTests.cs

@@ -105,6 +105,22 @@ public sealed class SarifOutputGeneratorTests
             r.Level == SarifLevel.Warning);
     }
 
+    [Fact(DisplayName = "Delta verdict reference included in material change properties")]
+    public void DeltaVerdictReference_IncludedInMaterialChangeProperties()
+    {
+        // Arrange
+        var input = CreateBasicInput() with { DeltaVerdictReference = "sha256:delta" };
+
+        // Act
+        var sarifLog = _generator.Generate(input);
+
+        // Assert
+        var result = sarifLog.Runs[0].Results.First(r => r.RuleId == "SDIFF001");
+        result.Properties.Should().NotBeNull();
+        result.Properties!.Value.Should().ContainKey("deltaVerdictRef");
+        result.Properties["deltaVerdictRef"].Should().Be("sha256:delta");
+    }
+
     [Fact(DisplayName = "Hardening regressions generate error-level results")]
     public void HardeningRegressions_GenerateErrorResults()
     {