Scaled down and converted images before sending them to AI models (#1101)

app/Tests/Tools/ModelImageFormatTests.cs

@@ -0,0 +1,46 @@
+using AIStudio.Chat;
+using AIStudio.Tools.Rust;
+
+namespace AIStudio.Tests.Tools;
+
+/// <summary>
+/// Checks which image formats may be attached for an AI model.
+/// </summary>
+/// <remarks>
+/// The runtime decides which formats it can prepare for a model, see prepare_image_for_model in
+/// runtime/src/image.rs. An image the app lets through but the runtime cannot prepare would only
+/// fail once the message is sent; one the app refuses although the runtime could prepare it would
+/// be refused for nothing.
+/// </remarks>
+[TestFixture]
+public sealed class ModelImageFormatTests
+{
+    /// <summary>
+    /// The extensions model_input_format in runtime/src/image.rs accepts.
+    /// </summary>
+    private static readonly string[] RUNTIME_MODEL_FORMATS = ["jpg", "jpeg", "png", "webp", "gif", "bmp", "tif", "tiff"];
+
+    [Test]
+    public void EveryFormatTheRuntimePreparesMayBeAttached()
+    {
+        Assert.That(FileTypes.MODEL_IMAGE.FlattenExtensions(), Is.EquivalentTo(RUNTIME_MODEL_FORMATS));
+    }
+
+    [Test]
+    public void OnlyFormatsWithoutADecoderAreRefused()
+    {
+        var refused = FileTypes.IMAGE.FlattenExtensions().Except(FileTypes.MODEL_IMAGE.FlattenExtensions());
+
+        Assert.That(refused, Is.EquivalentTo(new[] { "svg", "heic", "avif" }));
+    }
+
+    [Test]
+    public void ATifFileIsAnImage()
+    {
+        Assert.Multiple(() =>
+        {
+            Assert.That(FileAttachment.FromPath("/tmp/scan.tif").IsImage, Is.True);
+            Assert.That(FileTypes.IsAllowedPath("/tmp/scan.tif", FileTypes.MODEL_IMAGE), Is.True);
+        });
+    }
+}