Fixed Semantic Search with external data sources (ERI servers) (#1090)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/Tests/Settings/DataSourceERICancellationTests.cs

@@ -0,0 +1,87 @@
+using AIStudio.Settings;
+using AIStudio.Settings.DataModel;
+using AIStudio.Tools.ERIClient.DataModel;
+using AIStudio.Tools.RAG;
+using AIStudio.Tools.Services;
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+
+using ChatThread = AIStudio.Chat.ChatThread;
+
+namespace AIStudio.Tests.Settings;
+
+/// <summary>
+/// Checks what a search of an ERI data source does when it is cancelled, and when its server fails.
+/// </summary>
+/// <remarks>
+/// The ERI client answers a cancellation like any other failure, because its other callers pass a
+/// timeout of their own and expect an answer. A search the user cancelled has to stop, though,
+/// rather than report the data source as not searched and carry on. A server which fails without
+/// anybody cancelling still makes the data source count as not searched.
+/// </remarks>
+[TestFixture]
+public sealed class DataSourceERICancellationTests
+{
+    // Nothing listens on port 1 of the own machine, so a request fails right away:
+    private static readonly DataSourceERI_V1 UNREACHABLE = new()
+    {
+        Id = "33333333-3333-3333-3333-333333333333",
+        Name = "Intranet",
+        Type = DataSourceType.ERI_V1,
+        Hostname = "http://127.0.0.1",
+        Port = 1,
+        AuthMethod = AuthMethod.NONE,
+        SecurityPolicy = DataSourceSecurity.ALLOW_ANY,
+        MaxMatches = 10,
+    };
+
+    private RustService rustService = null!;
+    private ServiceProvider serviceProvider = null!;
+    private IServiceProvider previousServiceProvider = null!;
+
+    [SetUp]
+    public void PrepareServices()
+    {
+        this.rustService = new RustService("1", "unused");
+        var settingsManager = new SettingsManager(NullLogger<SettingsManager>.Instance, this.rustService);
+
+        this.previousServiceProvider = Program.SERVICE_PROVIDER;
+        this.serviceProvider = new ServiceCollection()
+            .AddSingleton(this.rustService)
+            .AddSingleton(settingsManager)
+            .AddLogging()
+            .BuildServiceProvider();
+
+        Program.SERVICE_PROVIDER = this.serviceProvider;
+    }
+
+    [TearDown]
+    public void RestoreApplicationState()
+    {
+        Program.SERVICE_PROVIDER = this.previousServiceProvider;
+        this.serviceProvider.Dispose();
+        this.rustService.Dispose();
+    }
+
+    [Test]
+    public void ACancelledSearchStops()
+    {
+        using var cancellation = new CancellationTokenSource();
+        cancellation.Cancel();
+
+        Assert.CatchAsync<OperationCanceledException>(async () => await UNREACHABLE.RetrieveDataAsync("query", 1, new ChatThread(), cancellation.Token), "Reporting the data source as not searched would carry on after the user cancelled.");
+    }
+
+    [Test]
+    public async Task AFailingServerMakesTheDataSourceCountAsNotSearched()
+    {
+        var page = await UNREACHABLE.RetrieveDataAsync("query", 1, new ChatThread());
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(page.Contexts, Is.Empty);
+            Assert.That(page.Gaps, Is.EqualTo(new[] { RetrievalGap.NOT_SEARCHED }), "Nobody cancelled, so the model learns that this data source is missing rather than empty.");
+        });
+    }
+}