Added the Model Comparison assistant for blind comparisons of two models (#1009)

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

app/Tests/Assistants/ModelComparison/ModelComparisonJudgeVerdictTests.cs

@@ -0,0 +1,79 @@
+using AIStudio.Assistants.ModelComparison;
+
+namespace AIStudio.Tests.Assistants.ModelComparison;
+
+/// <summary>
+/// Checks how the judge's raw answer is turned into a verdict.
+/// </summary>
+/// <remarks>
+/// The judge is asked for one JSON object and nothing else, but a model rarely holds to that
+/// perfectly. Parsing has to look past a stray sentence around the object, and has to end up with a
+/// verdict which is not ModelComparisonJudgeVerdict.Completed rather than throw when
+/// there is nothing usable to read.
+/// </remarks>
+[TestFixture]
+public sealed class ModelComparisonJudgeVerdictTests
+{
+    [Test]
+    public void APlainJsonObjectIsRead()
+    {
+        var verdict = ModelComparisonJudgeVerdict.Parse("Judge", true, """{"preferred": "A", "reasoning": "It kept every number from the document."}""");
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(verdict.Completed, Is.True);
+            Assert.That(verdict.Label, Is.EqualTo("Judge"));
+            Assert.That(verdict.Preferred, Is.EqualTo(ModelComparisonVote.COLUMN_A));
+            Assert.That(verdict.Reasoning, Is.EqualTo("It kept every number from the document."));
+        }
+    }
+
+    [Test]
+    public void APreferenceIsReadWithoutRegardToCase()
+    {
+        var verdict = ModelComparisonJudgeVerdict.Parse("Judge", true, """{"preferred": "tie", "reasoning": "Both cover the same points."}""");
+
+        Assert.That(verdict.Preferred, Is.EqualTo(ModelComparisonVote.TIE));
+    }
+
+    [Test]
+    public void TextAroundTheJsonObjectIsIgnored()
+    {
+        var verdict = ModelComparisonJudgeVerdict.Parse("Judge", true, """
+            Sure, here is my verdict:
+            ```json
+            {"preferred": "B", "reasoning": "It is shorter and just as complete."}
+            ```
+            """);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(verdict.Completed, Is.True);
+            Assert.That(verdict.Preferred, Is.EqualTo(ModelComparisonVote.COLUMN_B));
+        }
+    }
+
+    [Test]
+    public void AJudgeWhichDidNotAnswerIsNotCompleted()
+    {
+        var verdict = ModelComparisonJudgeVerdict.Parse("Judge", false, string.Empty);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(verdict.Completed, Is.False);
+            Assert.That(verdict.Preferred, Is.Null);
+            Assert.That(verdict.Reasoning, Is.Empty);
+        }
+    }
+
+    [TestCase("Sorry, I cannot help with that.")]
+    [TestCase("""{"reasoning": "Missing the preference field."}""")]
+    [TestCase("""{"preferred": "C", "reasoning": "Not one of the three allowed values."}""")]
+    [TestCase("""{"preferred": "A", "reasoning": }""")]
+    public void AnUnreadableAnswerIsNotCompleted(string judgeText)
+    {
+        var verdict = ModelComparisonJudgeVerdict.Parse("Judge", true, judgeText);
+
+        Assert.That(verdict.Completed, Is.False);
+    }
+}