Add PII redaction POC for secure LLM prompting.

Implements detect-redact-sanitize pipeline with regex, domain rules, and ONNX NER before the LLM boundary, plus NUnit tests and Xenovex push documentation. Co-authored-by: Cursor <cursoragent@cursor.com>
2026-07-07 13:05:07 +05:30
commit dfc81dea28
60 changed files with 3283 additions and 0 deletions
--- a/tests/PiiRedaction.Core.Tests/Detection/DomainRulePiiDetectorTests.cs
+++ b/tests/PiiRedaction.Core.Tests/Detection/DomainRulePiiDetectorTests.cs
@@ -0,0 +1,70 @@
+using FluentAssertions;
+using PiiRedaction.Core.Detection;
+using PiiRedaction.Core.Models;
+
+namespace PiiRedaction.Core.Tests.Detection;
+
+[TestFixture]
+public sealed class DomainRulePiiDetectorTests
+{
+    private readonly DomainRulePiiDetector _detector = new();
+
+    [Test]
+    public void Detect_PositiveLoanNumber_ReturnsValueOnly()
+    {
+        var entities = _detector.Detect("Loan LN-456789 active.");
+
+        entities.Should().ContainSingle(entity =>
+            entity.Type == PiiEntityType.LoanNumber &&
+            entity.Value == "LN-456789" &&
+            entity.Source == PiiDetectionSource.Domain);
+    }
+
+    [Test]
+    public void Detect_PositiveCustomerId_ReturnsEntity()
+    {
+        var entities = _detector.Detect("CustomerId CID-1234 found.");
+
+        entities.Should().ContainSingle(entity =>
+            entity.Type == PiiEntityType.CustomerId &&
+            entity.Value == "CID-1234");
+    }
+
+    [Test]
+    public void Detect_PositiveAccountNumber_ReturnsEntity()
+    {
+        var entities = _detector.Detect("Account ACC-123456 open.");
+
+        entities.Should().ContainSingle(entity =>
+            entity.Type == PiiEntityType.AccountNumber &&
+            entity.Value == "ACC-123456");
+    }
+
+    [TestCase("LN-12345")]
+    [TestCase("XLN-456789")]
+    [TestCase("CID-123")]
+    [TestCase("ACC-12345")]
+    public void Detect_InvalidDomainIds_ReturnsEmpty(string text)
+    {
+        _detector.Detect(text).Should().BeEmpty();
+    }
+
+    [Test]
+    public void Detect_LoanNumberLabel_PreservesLabelInSurroundingText()
+    {
+        const string text = "LoanNumber LN-456789 end.";
+        var entity = _detector.Detect(text).Single();
+
+        entity.Value.Should().Be("LN-456789");
+        entity.StartIndex.Should().Be("LoanNumber ".Length);
+    }
+
+    [TestCase(null)]
+    [TestCase("")]
+    [TestCase("   ")]
+    public void Detect_InvalidInput_ThrowsArgumentException(string? text)
+    {
+        var action = () => _detector.Detect(text!);
+        action.Should().Throw<ArgumentException>();
+    }
+}