Added a home page prompt for missing API keys of enterprise providers (#1056)

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

app/Tests/Tools/UserAPIKeys/UserAPIKeyCheckTests.cs

@@ -0,0 +1,45 @@
+using AIStudio.Provider;
+using AIStudio.Tools.UserAPIKeys;
+
+namespace AIStudio.Tests.Tools.UserAPIKeys;
+
+/// <summary>
+/// Checks what AI Studio reads from the models a provider loads with the API key the user entered.
+/// </summary>
+/// <remarks>
+/// Only a refusal keeps the key out of the OS keyring, and only a list with models counts as accepted. Many
+/// providers succeed with an empty list whatever the key, for example for a kind of model they do not offer;
+/// telling the user that such a key was accepted would be a promise nobody checked.
+/// </remarks>
+[TestFixture]
+public sealed class UserAPIKeyCheckTests
+{
+    [TestCase(ModelLoadFailureReason.INVALID_OR_MISSING_API_KEY)]
+    [TestCase(ModelLoadFailureReason.AUTHENTICATION_OR_PERMISSION_ERROR)]
+    public void ARefusedSignInRejectsTheKey(ModelLoadFailureReason failureReason)
+    {
+        Assert.That(PendingUserAPIKeys.ClassifyCheck(ModelLoadResult.Failure(failureReason)), Is.EqualTo(UserAPIKeyCheckOutcome.REJECTED));
+    }
+
+    [Test]
+    public void ModelsLoadedWithTheKeyAcceptIt()
+    {
+        Assert.That(PendingUserAPIKeys.ClassifyCheck(ModelLoadResult.FromModels([new Model("gpt-6", "GPT-6")])), Is.EqualTo(UserAPIKeyCheckOutcome.ACCEPTED));
+    }
+
+    [Test]
+    public void AnEmptyListTellsNothingAboutTheKey()
+    {
+        Assert.That(PendingUserAPIKeys.ClassifyCheck(ModelLoadResult.FromModels([])), Is.EqualTo(UserAPIKeyCheckOutcome.NOT_CHECKED));
+    }
+
+    [TestCase(ModelLoadFailureReason.INSUFFICIENT_QUOTA)]
+    [TestCase(ModelLoadFailureReason.TOO_MANY_REQUESTS)]
+    [TestCase(ModelLoadFailureReason.PROVIDER_UNAVAILABLE)]
+    [TestCase(ModelLoadFailureReason.INVALID_RESPONSE)]
+    [TestCase(ModelLoadFailureReason.UNKNOWN)]
+    public void AnyOtherFailureTellsNothingAboutTheKey(ModelLoadFailureReason failureReason)
+    {
+        Assert.That(PendingUserAPIKeys.ClassifyCheck(ModelLoadResult.Failure(failureReason)), Is.EqualTo(UserAPIKeyCheckOutcome.NOT_CHECKED));
+    }
+}