Allowed the Batch Processing assistant to process images (#1087)

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

app/Tests/Provider/ImageSizeLimitTests.cs

@@ -0,0 +1,45 @@
+using AIStudio.Chat;
+using AIStudio.Provider;
+
+namespace AIStudio.Tests.Provider;
+
+/// <summary>
+/// Checks how large an image may be when we send it through a provider.
+/// </summary>
+/// <remarks>
+/// A provider states its limit or says nothing. Either way, TryAsBase64 skips every image above our
+/// own limit, so a larger limit of a provider must never reach the checks done before sending.
+/// </remarks>
+[TestFixture]
+public sealed class ImageSizeLimitTests
+{
+    [Test]
+    public void AnthropicLeavesRoomForTheBase64OfTheImage()
+    {
+        Assert.Multiple(() =>
+        {
+            Assert.That(LLMProviders.ANTHROPIC.GetMaxImageSizeBytes(), Is.EqualTo(3_932_160));
+            Assert.That(IImageSourceExtensions.MaxImageSizeBytesFor(LLMProviders.ANTHROPIC), Is.EqualTo(3_932_160));
+        });
+    }
+
+    [Test]
+    public void AProviderWithoutAStatedLimitGetsOurOwn()
+    {
+        Assert.Multiple(() =>
+        {
+            Assert.That(LLMProviders.OPEN_AI.GetMaxImageSizeBytes(), Is.Null, "Nobody stated a limit, and no number stands in for that.");
+            Assert.That(IImageSourceExtensions.MaxImageSizeBytesFor(LLMProviders.OPEN_AI), Is.EqualTo(IImageSourceExtensions.MAX_IMAGE_SIZE_BYTES));
+        });
+    }
+
+    [Test]
+    public void NoProviderGetsMoreThanTryAsBase64Sends()
+    {
+        Assert.Multiple(() =>
+        {
+            foreach (var provider in Enum.GetValues<LLMProviders>())
+                Assert.That(IImageSourceExtensions.MaxImageSizeBytesFor(provider), Is.LessThanOrEqualTo(IImageSourceExtensions.MAX_IMAGE_SIZE_BYTES), provider.ToString());
+        });
+    }
+}