llm-pii-poc/tests/PiiRedaction.Core.Tests/Detection/DomainRulePiiDetectorTests.cs

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>();
    }
}