Let the sources of your own documents open at the page they were found on (#974)

app/Tests/Tools/RetrievalContextDescriptionTests.cs

@@ -0,0 +1,84 @@
+using System.Text;
+
+using AIStudio.Tools.RAG;
+
+namespace AIStudio.Tests.Tools;
+
+/// <summary>
+/// Checks what the AI is told about a passage before it reads it.
+/// </summary>
+/// <remarks>
+/// The page a passage sits on travels from the runtime through the index into the retrieval
+/// context, but it used to stop there: the AI was given the file and nothing else, so an answer
+/// could name the document it rests on but never the place in it. A source which has no page, a
+/// slide for instance, must stay silent rather than claim one.
+/// </remarks>
+[TestFixture]
+public sealed class RetrievalContextDescriptionTests
+{
+    [Test]
+    public void AKnownPageIsPartOfWhatTheAIIsTold()
+    {
+        var description = Describe(TextContext(pageNumber: 12));
+
+        Assert.That(description, Does.Contain("Content location: page 12"), "The AI is told the page, so it can say where an answer comes from.");
+    }
+
+    [Test]
+    public void APassageWithoutAPageClaimsNone()
+    {
+        var description = Describe(TextContext(pageNumber: null));
+
+        Assert.That(description, Does.Not.Contain("Content location"), "A slide or a sheet has no page, and none is invented for it.");
+    }
+
+    /// <remarks>
+    /// The location belongs to the document, so it is stated with it and before the passage itself
+    /// follows further down.
+    /// </remarks>
+    [Test]
+    public void ThePageIsStatedWithTheDocumentItBelongsTo()
+    {
+        var description = Describe(TextContext(pageNumber: 12));
+        var lines = description.Split('\n').Select(line => line.Trim()).Where(line => line.Length > 0).ToArray();
+
+        Assert.That(lines, Is.EqualTo(new[]
+        {
+            "Data source name: Handbooks",
+            "Content category: TEXT",
+            "Content type: TEXT_DOCUMENT",
+            "Content path: /docs/handbook.pdf",
+            "Content location: page 12",
+        }), "Name, kind, path and place of the document, in that order.");
+    }
+
+    [Test]
+    public void AdditionalLinksStillFollowTheLocation()
+    {
+        var description = Describe(TextContext(pageNumber: 12, links: ["https://example.com/handbook"]));
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(description, Does.Contain("Additional links:"), "The links a data source delivers are still passed on.");
+            Assert.That(description.IndexOf("Content location", StringComparison.Ordinal), Is.LessThan(description.IndexOf("Additional links", StringComparison.Ordinal)), "The place inside the document is stated before links pointing elsewhere.");
+        });
+    }
+
+    private static string Describe(IRetrievalContext retrievalContext)
+    {
+        var builder = new StringBuilder();
+        IRetrievalContextExtensions.AppendContextDescription(builder, retrievalContext);
+        return builder.ToString();
+    }
+
+    private static RetrievalTextContext TextContext(int? pageNumber, IReadOnlyList<string>? links = null) => new()
+    {
+        DataSourceName = "Handbooks",
+        Category = RetrievalContentCategory.TEXT,
+        Type = RetrievalContentType.TEXT_DOCUMENT,
+        Path = "/docs/handbook.pdf",
+        Links = links ?? [],
+        MatchedText = "The mixing console is described here.",
+        PageNumber = pageNumber,
+    };
+}